Evaluation and GWAS of radicle gravitropic response in a core rice germplasms population

Evaluation and GWAS of radicle gravitropic response in a core rice germplasms population | Research Square window.SnipcartSettings = { analytics: { enabled: false } }; (function() { var accessVector = localStorage.getItem('access_vector') || ''; window.dataLayer = window.dataLayer || []; if (accessVector) { window.dataLayer.push({ user: { profile: { profileInfo: { snid: accessVector } } } }); } })(); (function(w,d,s,l,i){w[l]=w[l]||[];w[l].push({'gtm.start':new Date().getTime(),event:'gtm.js'});var f=d.getElementsByTagName(s)[0],j=d.createElement(s),dl=l!='dataLayer'?'&l='+l:'';j.async=true;j.src='https://www.googletagmanager.com/gtm.js?id='+i+dl;f.parentNode.insertBefore(j,f);})(window,document,'script','dataLayer','GTM-K279D39R'); Browse Preprints In Review Journals COVID-19 Preprints AJE Video Bytes Research Tools Research Promotion AJE Professional Editing AJE Rubriq About Preprint Platform In Review Editorial Policies Our Team Advisory Board Help Center Sign In Submit a Preprint Cite Share Download PDF Research Article Evaluation and GWAS of radicle gravitropic response in a core rice germplasms population qiaojun lou, Qingsong Li, Fangjun Feng, Ryan Joynson, Yunan Yang, and 2 more This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-64873/v2 This work is licensed under a CC BY 4.0 License Status: Published Journal Publication published 28 Aug, 2021 Read the published version in Plant and Soil → Version 2 posted You are reading this latest preprint version Show more versions Abstract Aims: Gravitropism is one of the primary determinants of root development, facilitating root penetration into soil and subsequent absorption of water and nutrients. To study the gravitropism of the radicle roots, we conducted this research. Methods: The gravitropism of 226 Chinese rice micro-core accessions and drought-resistant core accessions were assessed through the modified gravity-bending experiment and genome-wide association analysis (GWAS) was used to map the associated QTLs. Results: The average value of gravitropic response speed of radicle roots was 41.05°/h from 16.77°/h to 62.83°/h. Significant difference (p < 0.002) in gravity response speed between Indica (42.49°/h) and Japonica (39.71°/h) subspecies was found. The gravitational response speed of radicle roots was significantly positively correlated with the number of deep roots (r =0.16), the growth speed of radicle roots (r =0.21) and the drought resistance coefficient (r=0.14). Conclusions: In total, 3 QTLs (quantitative traits) associated with gravitropic response speed were identified on chromosome 4,11 and 12. There are some known QTLs relating to roots traits and drought resistance located nearby the QTLs identified here, which confirms the close relationship between radicle gravitropism and the drought resistance. From within these intervals, 5 candidate genes were screened for qPCR in 6 extreme rice varieties, demonstrating that gene LOC_Os12g29350 may regulate gravitropism negatively and confirming its candidacy for further study. Plant Physiology and Morphology rice gravitropism gravitropic response growth angle of radicle genome-wide association study (GWAS) Figures Figure 1 Figure 2 Figure 3 Figure 4 Introduction Scientists have been trying to understand gravitropism for more than 120 years (Darwin and Darwin 1880). Gravitropism is the orientation of growth in response to gravity, which is necessary for roots to grow into soil, to acquire water and nutrients and to anchor plants, providing stability and preventing lodging. The starch–statolith hypothesis and the Cholodny–Went theory attempts to explain some aspects of gravitropism (Haberlandt 1900; Němec 1900; Went 1926; Cholodny N 1927). The starch–statolith hypothesis proposes that the starch-filled amyloplasts of gravity-sensing cells act as statoliths, signalling the direction of gravity by their sedimentation. The Cholodny–Went theory indicated, gravity-bending is the result of differential accumulation of auxin on opposite sides of the elongation zone, causing differential growth and tip curvature. In addition, the mechanosensitive ion channel hypothesis also could explain some parts of the gravitropism(Ding and Pickard 1993). Multiple hormones and genes have been found to be involved in gravitropism previously (Blancaflor and Masson 2003; Baldwin et al. 2013; Mai et al. 2014; Ge and Chen 2016; Zhang et al. 2019). Auxin and its related transporters（e.g. AUX1 and AtPIN2）have been observed to regulate gravitropism (Bennett et al. 1996; Müller et al. 1998; Rigó et al. 2013). Cytokinin functions as an anti-gravitropic signaller in lateral roots(Waidmann et al. 2019). Additionally, brassinosteroid also play important role in the root gravitropic response(Kim et al. 2000; Chang et al. 2004; Amzallag and Vaisman 2006). The AGR1 gene involved in root gravitropism could increase root-growth sensitivity to auxin and decrease sensitivity to ethylene in Arabidopsis (Chen et al. 1998). The NPY genes play an essential role in root gravitropic responses in Arabidopsis(Li et al. 2011). Although the vast majority of research to date has been conducted in Arabidopsis thaliana , few examples of genes affecting gravitropism have been identified in crop species. The organization of the actin cytoskeleton influence the gravitropic response of primary roots of maize (Blancaflor and Hasenstein 1997). Maize LAZY1 mediates shoot gravitropism through regulating auxin transport(Dong et al. 2013). Rice is a staple food for nearly half of the world’s population. It has a typical fibrous root system. In rice, some mutants and genes related to gravitropism have been identified. LAZY1 gene controls rice shoot gravitropism through regulating polar auxin transport(Li et al. 2007), but the primary roots of lazy1 mutants show normal gravitropism and circumnutation (Yoshihara et al. 2013). Aem1 mutant causes defects in root development and gravity response (Debi et al. 2005a). Overexpression of OsRAA1 effects root development and root response to gravity(Ge et al. 2004). The mechanism of gravity sensing in plants is one of the most fascinating questions in molecular biology and because of the new availability of high-throughput sequencing and phenotyping technology, we can expand our knowledge of this trait through association analysis. For example, in the common bean, Liao et al mapped the QTLs controlling basal root gravitropism (Liao et al. 2004). Using a mapping population derived from a Bala × Azucena, two main QTLs for gravitropic response have been mapped to chromosome 6 and 11(Norton and Price 2009). Measurement of gravitropism related traits with a throughput lending itself to the sample size required for association analysis is now more feasible with tools such as the ROTATO, an automated camera that could help researchers to dissect the gravity-response(Mullen et al. 2000). Despite progress made in recent decades, processes involved in positive root gravitropic response in the root tip remain largely unclear in rice. Since root gravitropism is widely believed to be regulated by a tipping-point mechanism (Band et al. 2012), the gravitropic response speed could be represented by the bending angle of the seminal in agar-filled Perspex chambers after rotation as Uga et al (Uga et al. 2013) and Norton and Price(Norton and Price 2009) demonstrate. But there are usually large variances among the results of gravitropic response evaluation. To reduce the variance, we had carried out multiple tests to optimise this methodology. Here, using the optimized method we measured gravitropic response speed of an association mapping population consisting 226 core rice accessions and have been in depth studied on drought resistance (Lou et al. 2015; Ma et al. 2016), and identified several QTLs related to gravitropic response that can be deployed into marker assisted selection programmes. Results Gravitropic response speed of the natural population In this study, we detected the bending angle of radicle roots of 226 core rice accessions representing their gravitropic response speed (Table1). Among these accessions, the average value of gravitropic response speed of radicle roots was 41.05°/h. The fastest speed was 62.83°/h, meanwhile the slowest speed was 16.77°/h. The standard deviation and coefficient of variation were 6.42°/h and 15.63%, respectively. As shown in Fig. 1 , the gravitropic response speed of radicle roots generally presented a normal distribution and was mostly distributed between 31°/h to 51°/h, accounting for 89.4% of the total accessions. This indicated that this set of data was suitable for association mapping analysis of gravitropic response speed of radicle roots. Table 1. Gravitropic response speeds of the association mapping population. The ‘ t-test’ is value of student’s test of the gravitropic response speed between Indica and Japonica. Number of accessions Means （ °/h ） Range （ °/h ） Standard deviation （ SD, °/h ） Coefficient variation (CV, %) t-test Indica 133 42.49 16.77-62.83 6.41 15.32 0.002 Japonica 93 39.71 21.73-61.64 6.30 15.77 Total 226 41.05 62.83-16.77 6.42 15.63 Notable differences of gravitropic response speed were found between Indica and Japonica rice ( Table1 ). The gravitropic response speed of Indica rice was mostly distributed between 33.5°/h to 53.5°/h, accounting for 94.7% of the Indica accessions. As for the Japonica rice, it was mostly distributed at 33.5°/h to 48.5°/h, accounting for 90.3% of the Japonica accessions. The mean of gravitropic response speed of Indica (42.49°/h) was faster than that of Japonica (39.71°/h). Likewise, the range of variation in Indica (46.06°/h) was larger than that in Japonica (39.91°/h) . The standard deviation and coefficient of variation of Indica and Japonica accessions were 6.41°/h and 6.30°/h, 15.32% and 15.77%, respectively. Compared the gravitropic response speed of Indica and Japonica rice by student’s (t) test resulted in a p value of inequality at 0.002. This result suggested that there was significant difference in the gravitropic response speed between Indica and Japonica subspecies, and the gravity response speed of Indica radicle roots was significantly faster than that of Japonica rice. Correlation among gravitropic response speed, deep rooting phenotype and drought resistant index Multiple measurements for root phenotypes of these 226 accessions have been measured in an our previous study (Lou et al. 2015) . The ratio of the yield in dry fields to the yield in paddy fields was calculated as the yield-based drought resistant index (DRI). The original data of DRI was obtained from a previous study in our laboratory(Ma et al. 2016). Correlations were calculated between these measurements and the gravitropic response measurements to determine if these traits could be inherently linked. By comparing the correlation coefficient between gravitropic response speed and some agronomic traits ( Table 2 ), we observed that the gravitropic response speed was significantly positively correlated with tiller number (TN), deep roots (DR), growth speed of radicle roots (GSR) and drought resistant index (DRI) with correlation coefficients of 0.13, 0.16, 0.22 and 0.14, respectively. The results indicated that the speed of the gravitropic response of radicle roots was highly significantly positively correlated with the speed of radicle roots growth. The faster the gravitropic response, the faster the growth speed. At significance level α=0.05, the speed of the gravitropic response of radicle roots was also positively correlated with TN, DR and DRI. The faster the response speed, the larger the deep roots number as well as the drought resistant index. There was no significant correlation between the speed of gravitropic response and plant height (PH), shallow roots (SR), ratio of deep roots (RDR) or roots per tiller (R/T). Table 2. Correlation coefficient between gravitropic response speed and some agronomic traits Bending angle of radicle Plant height (PH) 0.03 Tiller number (TN) 0.13 * Deep roots number (DR) 0.16 * Shallow roots number (SR) 0.09 Total roots number (TR) 0.12 Ratio of deep roots (RDR) 0.05 Roots per tiller (R/T) 0.01 Growth speed of radicle (GSR) 0.22 ** Drought resistant index (DRI) 0.14 * Note: “*” means significance at P<0.05, “**” means significance at P<0.01. Then, 12 accessions with the fastest speed of gravitropic response were selected for further study, and the growth speed of radicle roots and DRI of this subset were measured ( Supplementary Table 1) . Among them, the DRI of Xiaohonggu, IAC1246 and Zaohandao was 1.06, 1.18 and 1.89, respectively. These 3 accessions could be chosen as donor parental lines for drought-resistant breeding in the future. GWAS of the gravitropic response speed of radicle roots The raw sequence data of this population have been uploaded to public databases: http://www.ncbi.nlm.nih.gov/bioproject/PRJNA260762 and ftp://ftp-trace.ncbi.nlm.nih.gov/sra/sra-instant/reads/ByRun/sra/SRR/SRR123/SRR12 39601(Lou et al. 2015). GWAS was carried out to associate gravitropic response speed to a responsible genomic location using the EMMA model. 3 significantly associated QTLs were detected at the threshold of p=10 -5 ( Fig. 2 , Table 3 ). A QTL named qGRS4 was mapped on the chromosome 4 (4774373bp), and other 2 QTLs named qGRS11 and qGRS12 located on each of chromosomes 11 and 12 (23451244bp and 17439378bp, respectively). Table 3 . SNP loci related to gravitational response identified by GWAS NO. QTL Lead SNP (bp) Chr Maf LD Range P value 1 qGRS4 404774373 4 0.08 180Kb 4.83E-06 2 qGRS11 1123451244 11 0.07 580Kb 7.77E-06 3 qGRS12 1217439378 12 0.20 1Mb 4.87E-06 Chr, chromosome; Maf, minor allele frequency; LD Range, linkage disequilibrium decay distance at r 2 >0.65. qPCR of candidate genes of gravitropic response According to the GWAS results and based on the annotation information from the Rice Genome Annotation Project (http://rice.plantbiology.msu.edu/) and our previous transcriptome data of rice root(Lou et al. 2017), 5 candidate genes in close proximity to the most associated SNPs that may relate with roots gravitropic response were chosen for further expression analysis ( Table 4 ). From Chromosome 4 to 12, they are an ethylene receptor, an A49-like RNA polymerase I associated factor family protein, a GRF-interacting factor 2, a wall-associated receptor kinase-like 2 precursors and an ATP binding protein. Table 4. Candidate genes of gravitropic response speed and their annotations QTL Candidate Gene ID Chromosome Annotation qGRS4 LOC_Os04g08740 ( ETR2 ) 4 Ethylene receptor qGRS11 LOC_Os11g40090 ( RPA49 ) 11 A49-like RNA polymerase I associated factor family protein LOC_Os11g40100 ( OsGIF1 ) 11 GRF-interacting factor 2 LOC_Os11g40430 ( RLCK341 ) 11 Wall-associated receptor kinase-like 2 precursors qGRS12 LOC_Os12g29350 12 ATP binding protein Based on gravitropic response speed, the fastest and slowest 3 extreme accessions were selected respectively from the 226 accessions. The fastest 3 extreme accessions were Zaohandao(F1), C22(F2) and Xianggu(F3), and the slowest were BLCO.BRANCO(S1), IPEACO162(S2) and Gaoyangdiandao(S3). The lead SNP (1217439378) of qGRS12 indicated different allele types between 2 groups of accessions, that all three slowest accessions with the G allele, while all three fastest accessions with the alleles of both A and G. The expression patterns of the five genes in these 6 accessions were shown in Fig. 3 . Demonstrating that the expression level of LOC_Os12g29350 in the three accessions with the fastest gravitropic response speed was much lower than that in the three accessions with the slowest gravitropic response speed, indicating that this gene may be involved in the negative regulation of gravitropic response. The expression level of ETR2 , RPA49 , OsGIF1 and RLCK341 was low in the 6 accessions, and no significant difference was found between the two types of rice with opposite gravitropic response speed. Discussion This natural mapping population has been re-sequenced and soundly assessed on root morphological characteristics and drought related traits in our previous research(Lou et al. 2015; Wu et al. 2015; Ma et al. 2016). Therefore, it is a good resource to study the relations between gravitropic response and other important agronomic traits, and to explore the genes controlling roots gravitropism. The gravitropic response of radicle is primarily controlled by genetic factors but is also significantly influenced by environmental conditions(Staves et al. 1997; Norton and Price 2009). Therefore, producing uniform and homogeneous growth environment is the precondition to carry out such experiments. However, it remains challenging to maintain an even soil environment to observe the hidden half from the soil. Although there will be obvious differences in the root phenotype of seeds growing in the agar and soil, this agar-based screening system represents more unbiased approach to assess a biological process, and it has been extensively used to study gravitropic responses (Müller et al. 1998; Debi et al. 2005b). Compared with the method used in other studies (Norton and Price 2009; Uga et al. 2013), we modified the measurement protocol. Before the sowing, all the seeds were screened carefully and cold soaked to normalize their germination vigour. The bending angle was then recorded after a shorter period of 1 hour after 90° rotation, that is not only to save time but also to detect early variation in the trait more profoundly. Since the first 1 hour is the most efficient time in gravity-bending, after this time point the gravitropic response reduces rapidly. To gain an accurate representation of this trait, 50 seeds per accession were used in this study. After removal of non-germinating/infected seeds/ odd roots, a minimum of 20 valid samples per accession were assessed. Root growth angle is an important trait that influences the ability of rice to avoid drought stress (Uga et al. 2015a, b), because the deep roots help plants to absorb water from deep soil. The gravitropic response determines the shape of the root system, especially in the vertical dimension. As we found in this study, the gravitropic response speed significantly positively correlated with the number of deep roots and the drought resistant index. The varieties that have better gravitropic response would therefore infer better drought tolerance. This means that the gravity-bending angle could become an early indicator to predict plants’ drought resistance in a cost effective high-throughput manner. Here we highlight three varieties that express the desirable gravitropism trait along with drought resistance that could be promising resources for drought resistant breeding and research (supplementary table1, bold). Near the lead associated SNP loci, five candidate genes were selected for further study. A serine/threonine kinase, ETR2 (LOC_Os04g08740), was found at a distance of about 40kb from the lead SNP of qGRS4 (4774373, Chr4), which is an ethylene receptor and acts as a negative regulator of ethylene signaling. Plants over-expressing ETR2 display reduced ethylene sensitivity, delayed floral transition and reduced seed set (Hada et al. 2009). A further 2 genes were found at an interval within 52 kb from qGRS11 (23451244, Chr11). One was related with the activity of RNA polymerase called RPA49 (LOC_Os11g40090), which interacts with SAD1 . A decline in the function of SAD1 leads to severe suppression of axillary bud outgrowth, delay in progression of developmental phases and poor root growth (Li et al. 2015). The other was OsGIF1 (LOC_Os11g40100), which function in floral organogenesis in rice (Liu et al. 2014). LOC_Os11g40430 ( RLCK341 ) is a cell wall-associated receptor kinase at a distance of 189kb from qGRS11 (23451244, Chr11) (Vij et al. 2008). Gene LOC_Os12g29350, an ATP-binding protein, was located approximately 20kb away from the qGRS12 (17439378, Chr12) QTL. In future studies, we will detect their expression on the different positions of radicle to verify their function in gravity response definitively. There are 11 known QTLs, that function in roots morphology and drought resistance, close to the 3 associated SNPs’ physical position in the genome ( http://qtaro.abr.affrc.go.jp/ ) ( Table 5) . One of them, QTL 11-1 controlling root thickness and number of roots past 100cm near the associated SNP on chromosome 11, was found to be co-segregated with marker C189 (Price 2002). And C189 also co-segregated with root-penetration QTLs (Price et al. 2000) and a radicle root morphology QTL - SRM11 both identified by Price et al in the same mapping population (Norton and Price 2009). This interval is therefore very important in the development of the root morphology. The other 10 QTLs are all related to drought resistance, three of which are located on chromosome11, and seven QTLs were on the chromosome 12(Moncada et al. 2001; Bernier et al. 2007). This work provides further evidence to the hypothesis that gravitropic response speed is corelated with drought resistance are intrinsically related traits. Table 5. Co-localisation of QTLs for gravitropic response speed with previously identified QTLs of root and drought resistance. The information of the reported QTLs is searched from http://qtaro.abr.affrc.go.jp/ . QTL/Gene Major category Character Chr Genome Start Genome End Reference Co-segregated marker Gravitropic response speed QTLs Associated SNP position 11-1 Morphological trait Root thickness, number of roots past 100cm 11 https://doi.org/10.1016/S0378-4290(02)00010-2 C189(23732960-23734930) qGRS11 Chr11-23451244 gpl11.1 Drought Tolerance Grains per plant 11 17246592 23651853 http://dx.doi.org/10.1007/s001220051616 gw11.1 Drought Tolerance 1000-grain weight 11 17246592 23651853 http://dx.doi.org/10.1007/s001220051616 gw11.1 Drought Tolerance 1000-grain weight 11 17246592 23651853 http://dx.doi.org/10.1007/s001220051616 qtl12.1 Drought tolerance Harvest index 12 9895474 17758636 https://doi.org/10.2135/cropsci2006.07.0495 RM7195-RM28166 qGRS12 Chr12-17439378 qtl12.1 Drought tolerance Panicle number m-2 12 9895474 17758636 https://doi.org/10.2135/cropsci2006.07.0495 RM7195-RM28166 qtl12.1 Drought tolerance Flowering delay 12 9895474 17758636 https://doi.org/10.2135/cropsci2006.07.0495 RM7195-RM28166 qtl12.1 Drought tolerance Grain yield 12 14257182 17546401 https://doi.org/10.2135/cropsci2006.07.0495 RM28048-RM511 qtl12.1 Drought tolerance Biomass yield 12 14257182 17758636 https://doi.org/10.2135/cropsci2006.07.0495 RM28048-RM28166 qtl12.1 Drought tolerance Plant heigh at maturity 12 14257182 17758636 https://doi.org/10.2135/cropsci2006.07.0495 RM28048-RM28166 qtl12.1 Drought tolerance Drought response index 12 14257182 17546401 https://doi.org/10.2135/cropsci2006.07.0495 RM28048-RM511 Conclusion This study modified the assessment method of radicle gravitropic response to be more efficient and precise. Using a natural population that already has plenty of root and drought resistance data, 3 significant associated QTLs were identified by GWAS. The trait of radicle gravitropic response speed found to be positively corelated with the deep roots and drought resistance. Five candidate genes have been chosen for further verification by qPCR in 6 extreme varieties, and LOC_Os12g29350 was higher expressed in the slow gravitropic response varieties. Some known QTLs of roots traits and drought resistance located nearby the associated QTLs identified in this study, which confirmed the close relationship between radicle gravitropism and the drought resistance. Materials And Methods Plant material The association population used in this study is composed of 131 rice accessions from the mini-core collection of Chinese rice germplasm along with 95 rice accessions from core drought-resistance core rice germplasm collection. Of this population, 133 accessions are Indica rice and 93 accessions are Japonica rice. All rice seeds were provided by Shanghai Agrobiological Gene Center and harvested in the same season. Evaluation of root gravitropism Based on the root gravitropic curvature experiments described by Uga et al(Uga et al. 2013) and Norton and Price et al.(Norton and Price 2009), the gravitropic response speed of radicle roots was measured with some modification. The growth direction of the root tip was first marked when the radicle root grew to 1-2 cm. The root tip was then rotated from the normal vertical axis to the horizontal axis by rotating the agarose plate by 90 degrees. Now under the effect of gravity, the growth direction of radicle root tip was observed, and its position marked again after a growth period of 1 hour. The angle between the two marked root tip growth directions was recorded as the gravitropic response speed. The ratio of radicle root length to the growth period, starting at the date of sowing, was recorded as the radicle root growth speed. The gravitropic response speed of each panel member was calculated after removing the outliers. At least 20 viable seeds for each accession were used to calculate for its average gravitropic response speed. There were 7 steps to evaluation of root gravitropism, and the details were shown as Fig.4 . (1) Screening seeds. Using salt solution with the specific gravity at 1.1, the sterile and mouldy grains were removed, and about 50 uniform and full seeds were left for further experiment. (2) Sterilization. The seeds were sterilized with a 2.5% sodium hypochlorite solution for 15 minutes. Then, the seeds were rinsed with running water to clear the disinfectant away. (3) Cold soaking. Put the seeds in culture dishes lined with filter paper. Added some tap-water into the dishes to just submerge the seeds. Then covered the dishes with plastic wrap and stored in a 4℃ refrigerator for 7 days to make seeds fully soaked and ready for germination. (4) Making agarose gel. The 0.8% agarose was boiled and cooled, then poured into cuboid plastic transparent germination board with a length of 12 cm, a width of 1.3 cm and a height of 10 cm, that have been placed in a container with depth more than 12 cm. The final height of the solid gel was about 9 cm. (5) Sowing. Before sowing, the seeds were placed in a 28°C growth chamber for about 19 h. After the agar gel was completely cooled and solidified, germination plates were token out from the container and a lid with a length of 12.3 cm, a width of 1.8 cm, and a height of 1.3 cm was added at the bottom. The seeds with the same germination status were selected and sown evenly on the agar plate with embryos downward. 7 seeds per board, and more than 5 boards per accession. The accession name and sowing time were marked on left margin of the board. (6) Rotation after first lineation. After sowing, the plates were placed in an incubator at 28°C without light. About 1 day later, when most of the radicle roots of the same accession grow to length at 1 to 2cm, a line tangent to the growth direction of the root tip was marked on the board, and the current time was recorded. Then, the plates were rotated 90°and put into the growth chamber at 28°C immediately. (7) Second lineation. After 1 hour of growth, another line tangent to the growth direction of the new root tip was marked. The root length and bending angle of the root tip was measured according the two tangent lines, and gravitropic response speed and growth speed of radicle roots were then calculated as described above. Genome-wide association study To perform basic statistical analysis on the phenotypic traits, we calculated the average value, standard deviation, coefficient of variation and correlation coefficient as well as to make frequency distribution graph. The GWAS analysis was conducted via the efficient mixed-model association (EMMA) method which is available within the Genome Association and Prediction Integrated Tool (GAPIT) R package(Lipka et al. 2012).This mapping population has been used in our previous studies for a lot of other important agronomic traits, so its molecular data and analysis method have been ready-made already(Lou et al. 2015; Wu et al. 2015; Ma et al. 2016). Totally, 3038555 SNPs with the minor allele frequency (MAF) of ≥5% across the panel were used for GWAS. The model was adjusted using a kinship matrix and principal component eigenvectors to remove the confounding effects of hidden family relationships within the population and population structure. A kinship matrix was created following the Van Raden protocol within GAPIT, and the first 2 components were used in principal components (PC) adjustment. The threshold of -log 10 (P) =5.0 was used to declare the presence of associated QTLs (quantitative traits loci) for GWAS mapping. According to the GWAS results, the annotation information of all genes within the range of 200 kb on the two flanks of the lead associated SNP loci was analyzed and the genes whose function are known to may be relate to roots development were selected for further expression test. The linkage disequilibrium(LD) decay distance in Indica and Japonica extends to between ~75 and 200 kb, so the annotated genes in the range of 200 kb were considered here(Mather et al. 2007). Additionally, a further selection step was carried out using transcriptome data of rice root(Lou et al. 2017), where genes that were highly expressed in roots were preferentially selected for further analysis. RNA extraction and expression verification To determine if selected candidate genes were differentially expressed between lines in the population, qPCR was conducted. A total of 6 accessions were used for expression verification, using three extreme accessions with the fastest and three with the slowest gravitropic response speed that had been selected from the association population of 226 rice accessions. The radicle roots were sampled when they grew to 1-2 cm and were flash frozen in liquid nitrogen, then stored at -80 °C for later use. The total RNA of 10 pooled radicle roots was extracted using the TRNzol reagent (TIANGEN), and cDNA was synthesized by EasyScript®One-step gDNA Removal and cDNA Synthesis SuperMix following the manufacturers protocol (TransGen Biotech). Primer Premier v5.0 was used to design primers using the genome sequence of Nipponbare as a sequence reference ( Supplementary Table 2 ), the target fragment lengths were expected to be between 150bp - 250bp. Real time quantitative PCR was performed in 96-well plates with an Applied Biosystems CFX96 Real-Time PCR Detection System using TransStart Top Green qPCR SuperMix (TransGen Biotech). Actin gene was used as reference gene here. All assays were carried out in triplicate or greater and the expression levels were calculated using the relative quantitation method (ΔΔCT). Abbreviations GWAS: genome-wide association analysis; QTLs: quantitative traits; SD: standard deviation; CV: coefficient variation; PH: Plant height; TN: tiller number; DR: deep roots number; SR: shallow roots number; TR: total roots number; RDR: ratio of deep roots; R/T: roots per tiller; GSR: growth speed of radicle; DRI: drought resistant index; LD: linkage disequilibrium. Declarations Funding ： This work was supported by Shanghai Agriculture Applied Technology Development Program, China (G2015060101), and the Shanghai Natural Science Foundation (19ZR1446900, 18ZR1433300). Conflicts of interest/Competing interests ：The authors have no conflicts of interest to declare that are relevant to the content of this article Ethics approval ：Not applicable Consent to participate ： Not applicable Consent for publication ： Not applicable Availability of data and material ： The genetic data of this population can be downloaded from http://www.ncbi.nlm.nih.gov/bioproject/PRJNA260762 and ftp://ftp-trace.ncbi.nlm.nih.gov/sra/sra-instant/reads/ByRun/sra/SRR/SRR123/SRR12 39601. Code availability ： Not applicable Authors' contributions ：Qiaojun Lou and Liang Chen conceptualized the study; QingSong Li carried out phenotyping studies and curated the data; FangJun Feng performed the GWAS analysis; QiaoJun Lou and YuNan Yang drafted the manuscript under the supervision of LiJun Luo; Liang Chen and Ryan Joynson reviewed and edited the final manuscript. The authors all read and approved the final manuscript. Acknowledgements ： We thank the Huazhong Agriculture University that provided the SNP information of Chinese core rice accessions. References Amzallag GN, Vaisman J (2006) Influence of brassinosteroids on initiation of the root gravitropic response in Pisum sativum seedlings. Biol Plant 50:283–286. https://doi.org/10.1007/s10535-006-0021-5 Baldwin KL, Strohm AK, Masson PH (2013) Gravity sensing and signal transduction in vascular plant primary roots. Am J Bot 100:126–142. https://doi.org/10.3732/ajb.1200318 Band LR, Wells DM, Larrieu A, et al (2012) Root gravitropism is regulated by a transient lateral auxin gradient controlled by a tipping-point mechanism. Proc Natl Acad Sci U S A 109:4668–4673. https://doi.org/10.1073/pnas.1201498109 Bennett MJ, Marchant A, Green HG, et al (1996) Arabidopsis AUX1 gene: A permease-like regulator of root gravitropism. Science (80- ) 273:948–950. https://doi.org/10.1126/science.273.5277.948 Bernier J, Kumar A, Ramaiah V, et al (2007) A large-effect QTL for grain yield under reproductive-stage drought stress in upland rice. Crop Sci 47:507–518. https://doi.org/10.2135/cropsci2006.07.0495 Blancaflor EB, Hasenstein KH (1997) The organization of the actin cytoskeleton in vertical and graviresponding primary roots of maize. Plant Physiol 113:1447–1455. https://doi.org/10.1104/pp.113.4.1447 Blancaflor EB, Masson PH (2003) Plant Gravitropism. Unraveling the Ups and Downs of a Complex Process. Plant Physiol. 133:1677–1690 Chang SC, Kim Y-S, Lee JY, et al (2004) Brassinolide interacts with auxin and ethylene in the root gravitropic response of maize (Zea mays). Physiol Plant 121:666–673. https://doi.org/10.1111/j.0031-9317.2004.00356.x Chen R, Hilson P, Sedbrook J, et al (1998) The Arabidopsis thaliana AGRAVITROPIC 1 gene encodes a component of the polar-auxin-transport efflux carrier. Proc Natl Acad Sci U S A 95:15112–15117. https://doi.org/10.1073/pnas.95.25.15112 Cholodny N (1927) Wuchshormone and Tropismen bei den Pflanzen. Biol Zentralbl 47:604–629 Darwin C, Darwin F (1880) The power of movement in plants. Cambridge University Press Debi BR, Chhun T, Taketa S, et al (2005a) Defects in root development and gravity response in the aem1 mutant of rice are associated with reduced auxin efflux. J Plant Physiol 162:678–685. https://doi.org/10.1016/j.jplph.2004.09.012 Debi BR, Taketa S, Ichii M (2005b) Cytokinin inhibits lateral root initiation but stimulates lateral root elongation in rice (Oryza sativa). J Plant Physiol 162:507–515. https://doi.org/10.1016/j.jplph.2004.08.007 Ding JP, Pickard BG (1993) Mechanosensory calcium-selective cation channels in epidermal cells. Plant J 3:83–110. https://doi.org/10.1046/j.1365-313x.1993.t01-4-00999.x Dong Z, Jiang C, Chen X, et al (2013) Maize LAZY1 mediates shoot gravitropism and inflorescence development through regulating auxin transport, auxin signaling, and light response. Plant Physiol 163:1306–1322. https://doi.org/10.1104/pp.113.227314 Ge L, Chen H, Jiang JF, et al (2004) Overexpression of OsRAA1 causes pleiotropic phenotypes in transgenic rice plants, including altered leaf, flower, and root development and root response to gravity. Plant Physiol 135:1502–1513. https://doi.org/10.1104/pp.104.041996 Ge L, Chen R (2016) Negative gravitropism in plant roots. Nat Plants 2:1–4. https://doi.org/10.1038/nplants.2016.155 Haberlandt G (1900) Über die Perzeption des geotropischen Reizes. Ber Dtsch Bot Ges 18:261–272. https://doi.org/10.1111/J.1438-8677.1900.TB04908.X Hada W, Bo Z, Cao WH, et al (2009) The Ethylene Receptor ETR2 delays floral transition and affects starch accumulation in rice. Plant Cell 21:1473–1494. https://doi.org/10.1105/tpc.108.065391 Kim SK, Chang SC, Lee EJ, et al (2000) Involvement of brassinosteroids in the gravitropic response of primary root of maize. Plant Physiol 123:997–1004. https://doi.org/10.1104/pp.123.3.997 Li P, Wang Y, Qian Q, et al (2007) LAZY1 controls rice shoot gravitropism through regulating polar auxin transport. Cell Res 17:402–410. https://doi.org/10.1038/cr.2007.38 Li W, Yoshida A, Takahashi M, et al (2015) SAD1, an RNA polymerase I subunit A34.5 of rice, interacts with Mediator and controls various aspects of plant development. Plant J 81:282–291. https://doi.org/10.1111/tpj.12725 Li Y, Dai X, Cheng Y, Zhao Y (2011) NPY genes play an essential role in root gravitropic responses in Arabidopsis. Mol Plant 4:171–179. https://doi.org/10.1093/mp/ssq052 Liao H, Yan X, Rubio G, et al (2004) Genetic mapping of basal root gravitropism and phosphorus acquisition efficiency in common bean. Funct Plant Biol 31:959. https://doi.org/10.1071/FP03255 Lipka AE, Tian F, Wang Q, et al (2012) GAPIT: Genome association and prediction integrated tool. Bioinformatics 28:2397–2399. https://doi.org/10.1093/bioinformatics/bts444 Liu H, Guo S, Xu Y, et al (2014) OsmiR396d-regulated OsGRFs function in floral organogenesis in rice through binding to their targets OsJMJ706 and OsCR4. Plant Physiol 165:160–174. https://doi.org/10.1104/pp.114.235564 Lou Q, Chen L, Mei H, et al (2017) Root transcriptomic analysis revealing the importance of energy metabolism to the development of deep roots in rice (Oryza sativa L.). Front Plant Sci 8:. https://doi.org/10.3389/fpls.2017.01314 Lou Q, Chen L, Mei H, et al (2015) Quantitative trait locus mapping of deep rooting by linkage and association analysis in rice. J Exp Bot 66:4749–4757. https://doi.org/10.1093/jxb/erv246 Ma X, Feng F, Wei H, et al (2016) Genome-wide association study for plant height and grain yield in rice under contrasting moisture regimes. Front Plant Sci 7:1–13. https://doi.org/10.3389/fpls.2016.01801 Ma X, Feng F, Zhang Y, et al (2019) A novel rice grain size gene OsSNB was identified by genome-wide association study in natural population. PLoS Genet 15:1–20. https://doi.org/10.1371/journal.pgen.1008191 Mai CD, Phung NTP, To HTM, et al (2014) Genes controlling root development in rice. Rice 7:1–11. https://doi.org/10.1186/s12284-014-0030-5 Mather KA, Caicedo AL, Polato NR, et al (2007) The extent of linkage disequilibrium in rice (Oryza sativa L.). Genetics 177:2223–2232. https://doi.org/10.1534/genetics.107.079616 Moncada P, Martínez CP, Borrero J, et al (2001) Quantitative trait loci for yield and yield components in an Oryza sativa × Oryza rufipogon BC2F2 population evaluated in an upland environment. Theor Appl Genet 102:41–52. https://doi.org/10.1007/s001220051616 Mullen JL, Wolverton C, Ishikawa H, Evans ML (2000) Kinetics of constant gravitropic stimulus responses in Arabidopsis roots using a feedback system. Plant Physiol 123:665–670. https://doi.org/10.1104/pp.123.2.665 Müller A, Guan C, Gälweiler L, et al (1998) AtPIN2 defines a locus of Arabidopsis for root gravitropism control. EMBO J 17:6903–6911. https://doi.org/10.1093/emboj/17.23.6903 Němec B (1900) 28. Bohumil Němec: Ueber die Art der Wahrnehmung des Schwerkraftreizes bei den Pflanzen. Ber Dtsch Bot Ges 18:241–245. https://doi.org/10.1111/J.1438-8677.1900.TB04905.X Norton GJ, Price AH (2009) Mapping of quantitative trait loci for seminal root morphology and gravitropic response in rice. Euphytica 166:229–237. https://doi.org/10.1007/s10681-008-9833-z Price A (2002) QTLs for Root Growth and Drought Resistance in Rice. In: Molecular Techniques in Crop Improvement. Springer Netherlands, pp 563–584 Price AH, Steele KA, Moore BJ, et al (2000) A combined RFLP and AFLP linkage map of upland rice (Oryza sativa L.) used to identify QTLs for root-penetration ability. Theor Appl Genet 100:49–56. https://doi.org/10.1007/s001220050007 Rigó G, Ayaydin F, Tietz O, et al (2013) Inactivation of plasma membrane-localized CDPK-RELATED KINASE5 decelerates PIN2 exocytosis and root gravitropic response in Arabidopsis. Plant Cell 25:1592–1608. https://doi.org/10.1105/tpc.113.110452 Staves MP, Wayne R, Leopold AC (1997) The effect of the external medium on the gravitropic curvature of rice ( Oryza sativa, Poaceae) roots. Am J Bot 84:1522–1529. https://doi.org/10.2307/2446613 Uga Y, Kitomi Y, Ishikawa S, Yano M (2015a) Genetic improvement for root growth angle to enhance crop production. Breed Sci 65:111–119. https://doi.org/10.1270/jsbbs.65.111 Uga Y, Kitomi Y, Yamamoto E, et al (2015b) A QTL for root growth angle on rice chromosome 7 is involved in the genetic pathway of DEEPER ROOTING 1. Rice 8:8. https://doi.org/10.1186/s12284-015-0044-7 Uga Y, Sugimoto K, Ogawa S, et al (2013) Control of root system architecture by DEEPER ROOTING 1 increases rice yield under drought conditions. Nat Genet 45:1097–1102. https://doi.org/10.1038/ng.2725 Vij S, Giri J, Dansana PK, et al (2008) The receptor-like cytoplasmic kinase (OsRLCK) gene family in rice: Organization, phylogenetic relationship, and expression during development and stress. Mol Plant 1:732–750. https://doi.org/10.1093/mp/ssn047 Waidmann S, Ruiz Rosquete M, Schöller M, et al (2019) Cytokinin functions as an asymmetric and anti-gravitropic signal in lateral roots. Nat Commun 10:1–14. https://doi.org/10.1038/s41467-019-11483-4 Went F (1926) On growth-accelerating substances in the coleoptile of Avena sativa. Proc K Ned Akad van Wet 30:10–19 Wu J, Feng F, Lian X, et al (2015) Genome-wide Association Study (GWAS) of mesocotyl elongation based on re-sequencing approach in rice. BMC Plant Biol 15:1–10. https://doi.org/10.1186/s12870-015-0608-0 Yoshihara T, Spalding EP, Iino M (2013) AtLAZY1 is a signaling component required for gravitropism of the Arabidopsis thaliana inflorescence. Plant J 74:267–279. https://doi.org/10.1111/tpj.12118 Zhang Y, He P, Ma X, et al (2019) Auxin‐mediated statolith production for root gravitropism. New Phytol 224:761–774. https://doi.org/10.1111/nph.15932 Amzallag GN, Vaisman J (2006) Influence of brassinosteroids on initiation of the root gravitropic response in Pisum sativum seedlings. Biol Plant 50:283–286. https://doi.org/10.1007/s10535-006-0021-5 Baldwin KL, Strohm AK, Masson PH (2013) Gravity sensing and signal transduction in vascular plant primary roots. Am J Bot 100:126–142. https://doi.org/10.3732/ajb.1200318 Band LR, Wells DM, Larrieu A, et al (2012) Root gravitropism is regulated by a transient lateral auxin gradient controlled by a tipping-point mechanism. Proc Natl Acad Sci U S A 109:4668–4673. https://doi.org/10.1073/pnas.1201498109 Bennett MJ, Marchant A, Green HG, et al (1996) Arabidopsis AUX1 gene: A permease-like regulator of root gravitropism. Science (80- ) 273:948–950. https://doi.org/10.1126/science.273.5277.948 Bernier J, Kumar A, Ramaiah V, et al (2007) A large-effect QTL for grain yield under reproductive-stage drought stress in upland rice. Crop Sci 47:507–518. https://doi.org/10.2135/cropsci2006.07.0495 Blancaflor EB, Hasenstein KH (1997) The organization of the actin cytoskeleton in vertical and graviresponding primary roots of maize. Plant Physiol 113:1447–1455. https://doi.org/10.1104/pp.113.4.1447 Blancaflor EB, Masson PH (2003) Plant Gravitropism. Unraveling the Ups and Downs of a Complex Process. Plant Physiol. 133:1677–1690 Chang SC, Kim Y-S, Lee JY, et al (2004) Brassinolide interacts with auxin and ethylene in the root gravitropic response of maize (Zea mays). Physiol Plant 121:666–673. https://doi.org/10.1111/j.0031-9317.2004.00356.x Chen R, Hilson P, Sedbrook J, et al (1998) The Arabidopsis thaliana AGRAVITROPIC 1 gene encodes a component of the polar-auxin-transport efflux carrier. Proc Natl Acad Sci U S A 95:15112–15117. https://doi.org/10.1073/pnas.95.25.15112 Cholodny N (1927) Wuchshormone and Tropismen bei den Pflanzen. Biol Zentralbl 47:604–629 Darwin C, Darwin F (1880) The power of movement in plants. Cambridge University Press Debi BR, Chhun T, Taketa S, et al (2005a) Defects in root development and gravity response in the aem1 mutant of rice are associated with reduced auxin efflux. J Plant Physiol 162:678–685. https://doi.org/10.1016/j.jplph.2004.09.012 Debi BR, Taketa S, Ichii M (2005b) Cytokinin inhibits lateral root initiation but stimulates lateral root elongation in rice (Oryza sativa). J Plant Physiol 162:507–515. https://doi.org/10.1016/j.jplph.2004.08.007 Ding JP, Pickard BG (1993) Mechanosensory calcium-selective cation channels in epidermal cells. Plant J 3:83–110. https://doi.org/10.1046/j.1365-313x.1993.t01-4-00999.x Dong Z, Jiang C, Chen X, et al (2013) Maize LAZY1 mediates shoot gravitropism and inflorescence development through regulating auxin transport, auxin signaling, and light response. Plant Physiol 163:1306–1322. https://doi.org/10.1104/pp.113.227314 Ge L, Chen H, Jiang JF, et al (2004) Overexpression of OsRAA1 causes pleiotropic phenotypes in transgenic rice plants, including altered leaf, flower, and root development and root response to gravity. Plant Physiol 135:1502–1513. https://doi.org/10.1104/pp.104.041996 Ge L, Chen R (2016) Negative gravitropism in plant roots. Nat Plants 2:1–4. https://doi.org/10.1038/nplants.2016.155 Haberlandt G (1900) Über die Perzeption des geotropischen Reizes. Ber Dtsch Bot Ges 18:261–272. https://doi.org/10.1111/J.1438-8677.1900.TB04908.X Hada W, Bo Z, Cao WH, et al (2009) The Ethylene Receptor ETR2 delays floral transition and affects starch accumulation in rice. Plant Cell 21:1473–1494. https://doi.org/10.1105/tpc.108.065391 Kim SK, Chang SC, Lee EJ, et al (2000) Involvement of brassinosteroids in the gravitropic response of primary root of maize. Plant Physiol 123:997–1004. https://doi.org/10.1104/pp.123.3.997 Li P, Wang Y, Qian Q, et al (2007) LAZY1 controls rice shoot gravitropism through regulating polar auxin transport. Cell Res 17:402–410. https://doi.org/10.1038/cr.2007.38 Li W, Yoshida A, Takahashi M, et al (2015) SAD1, an RNA polymerase I subunit A34.5 of rice, interacts with Mediator and controls various aspects of plant development. Plant J 81:282–291. https://doi.org/10.1111/tpj.12725 Li Y, Dai X, Cheng Y, Zhao Y (2011) NPY genes play an essential role in root gravitropic responses in Arabidopsis. Mol Plant 4:171–179. https://doi.org/10.1093/mp/ssq052 Liao H, Yan X, Rubio G, et al (2004) Genetic mapping of basal root gravitropism and phosphorus acquisition efficiency in common bean. Funct Plant Biol 31:959. https://doi.org/10.1071/FP03255 Lipka AE, Tian F, Wang Q, et al (2012) GAPIT: Genome association and prediction integrated tool. Bioinformatics 28:2397–2399. https://doi.org/10.1093/bioinformatics/bts444 Liu H, Guo S, Xu Y, et al (2014) OsmiR396d-regulated OsGRFs function in floral organogenesis in rice through binding to their targets OsJMJ706 and OsCR4. Plant Physiol 165:160–174. https://doi.org/10.1104/pp.114.235564 Lou Q, Chen L, Mei H, et al (2017) Root transcriptomic analysis revealing the importance of energy metabolism to the development of deep roots in rice (Oryza sativa L.). Front Plant Sci 8:. https://doi.org/10.3389/fpls.2017.01314 Lou Q, Chen L, Mei H, et al (2015) Quantitative trait locus mapping of deep rooting by linkage and association analysis in rice. J Exp Bot 66:4749–4757. https://doi.org/10.1093/jxb/erv246 Ma X, Feng F, Wei H, et al (2016) Genome-wide association study for plant height and grain yield in rice under contrasting moisture regimes. Front Plant Sci 7:1–13. https://doi.org/10.3389/fpls.2016.01801 Ma X, Feng F, Zhang Y, et al (2019) A novel rice grain size gene OsSNB was identified by genome-wide association study in natural population. PLoS Genet 15:1–20. https://doi.org/10.1371/journal.pgen.1008191 Mai CD, Phung NTP, To HTM, et al (2014) Genes controlling root development in rice. Rice 7:1–11. https://doi.org/10.1186/s12284-014-0030-5 Mather KA, Caicedo AL, Polato NR, et al (2007) The extent of linkage disequilibrium in rice (Oryza sativa L.). Genetics 177:2223–2232. https://doi.org/10.1534/genetics.107.079616 Moncada P, Martínez CP, Borrero J, et al (2001) Quantitative trait loci for yield and yield components in an Oryza sativa × Oryza rufipogon BC2F2 population evaluated in an upland environment. Theor Appl Genet 102:41–52. https://doi.org/10.1007/s001220051616 Mullen JL, Wolverton C, Ishikawa H, Evans ML (2000) Kinetics of constant gravitropic stimulus responses in Arabidopsis roots using a feedback system. Plant Physiol 123:665–670. https://doi.org/10.1104/pp.123.2.665 Müller A, Guan C, Gälweiler L, et al (1998) AtPIN2 defines a locus of Arabidopsis for root gravitropism control. EMBO J 17:6903–6911. https://doi.org/10.1093/emboj/17.23.6903 Němec B (1900) 28. Bohumil Němec: Ueber die Art der Wahrnehmung des Schwerkraftreizes bei den Pflanzen. Ber Dtsch Bot Ges 18:241–245. https://doi.org/10.1111/J.1438-8677.1900.TB04905.X Norton GJ, Price AH (2009) Mapping of quantitative trait loci for seminal root morphology and gravitropic response in rice. Euphytica 166:229–237. https://doi.org/10.1007/s10681-008-9833-z Price A (2002) QTLs for Root Growth and Drought Resistance in Rice. In: Molecular Techniques in Crop Improvement. Springer Netherlands, pp 563–584 Price AH, Steele KA, Moore BJ, et al (2000) A combined RFLP and AFLP linkage map of upland rice (Oryza sativa L.) used to identify QTLs for root-penetration ability. Theor Appl Genet 100:49–56. https://doi.org/10.1007/s001220050007 Rigó G, Ayaydin F, Tietz O, et al (2013) Inactivation of plasma membrane-localized CDPK-RELATED KINASE5 decelerates PIN2 exocytosis and root gravitropic response in Arabidopsis. Plant Cell 25:1592–1608. https://doi.org/10.1105/tpc.113.110452 Staves MP, Wayne R, Leopold AC (1997) The effect of the external medium on the gravitropic curvature of rice ( Oryza sativa, Poaceae) roots. Am J Bot 84:1522–1529. https://doi.org/10.2307/2446613 Uga Y, Kitomi Y, Ishikawa S, Yano M (2015a) Genetic improvement for root growth angle to enhance crop production. Breed Sci 65:111–119. https://doi.org/10.1270/jsbbs.65.111 Uga Y, Kitomi Y, Yamamoto E, et al (2015b) A QTL for root growth angle on rice chromosome 7 is involved in the genetic pathway of DEEPER ROOTING 1. Rice 8:8. https://doi.org/10.1186/s12284-015-0044-7 Uga Y, Sugimoto K, Ogawa S, et al (2013) Control of root system architecture by DEEPER ROOTING 1 increases rice yield under drought conditions. Nat Genet 45:1097–1102. https://doi.org/10.1038/ng.2725 Vij S, Giri J, Dansana PK, et al (2008) The receptor-like cytoplasmic kinase (OsRLCK) gene family in rice: Organization, phylogenetic relationship, and expression during development and stress. Mol Plant 1:732–750. https://doi.org/10.1093/mp/ssn047 Waidmann S, Ruiz Rosquete M, Schöller M, et al (2019) Cytokinin functions as an asymmetric and anti-gravitropic signal in lateral roots. Nat Commun 10:1–14. https://doi.org/10.1038/s41467-019-11483-4 Went F (1926) On growth-accelerating substances in the coleoptile of Avena sativa. Proc K Ned Akad van Wet 30:10–19 Wu J, Feng F, Lian X, et al (2015) Genome-wide Association Study (GWAS) of mesocotyl elongation based on re-sequencing approach in rice. BMC Plant Biol 15:1–10. https://doi.org/10.1186/s12870-015-0608-0 Yoshihara T, Spalding EP, Iino M (2013) AtLAZY1 is a signaling component required for gravitropism of the Arabidopsis thaliana inflorescence. Plant J 74:267–279. https://doi.org/10.1111/tpj.12118 Zhang Y, He P, Ma X, et al (2019) Auxin‐mediated statolith production for root gravitropism. New Phytol 224:761–774. https://doi.org/10.1111/nph.15932 Supplementary Files additionalfilesrevised.docx Supplementary Table 1. The top fast 12 varieties responding gravity in the 226 natural rice population. Supplementary Table 2. Primers used in this qPCR. Cite Share Download PDF Status: Published Journal Publication published 28 Aug, 2021 Read the published version in Plant and Soil → Version 2 posted You are reading this latest preprint version Show more versions Research Square lets you share your work early, gain feedback from the community, and start making changes to your manuscript prior to peer review in a journal. As a division of Research Square Company, we’re committed to making research communication faster, fairer, and more useful. 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Also discoverable on Platform About Our Team In Review Editorial Policies Advisory Board Help Center Resources Author Services Accessibility API Access RSS feed Manage Cookie Preferences © Research Square 2026 | ISSN 2693-5015 (online) Privacy Policy Terms of Service Do Not Sell My Personal Information {"props":{"pageProps":{"initialData":{"identity":"rs-64873","acceptedTermsAndConditions":true,"allowDirectSubmit":false,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":17392452,"identity":"ccd1d8cb-4148-4d90-82c4-206d955a2213","order_by":0,"name":"qiaojun lou","email":"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAZAAAAAyAQMAAABI0h/eAAAABlBMVEX///8AAABVwtN+AAAACXBIWXMAAA7EAAAOxAGVKw4bAAAAsUlEQVRIie3RMQqDMBTG8a8IyRLrKnTwCroUjxMR7OLSsZCKk1t7JkGIh7BDoCAd7VKcSpVe4GUrNP/h4y2/6QEu1w+2BTJjRxiQx9aEhZaEy/E0q3MEfrk/oG4EIkwxCN0ntej3KfRIIKEsBjAtERYs3tQdjRznty2B36iVeIZGhMl3/rVNGqEZpCaQgJfZc35VUcAbb5oUgQClXKb7PkhSAHBol6nWy5towuVyuf6tD2bLNFlnvid1AAAAAElFTkSuQmCC","orcid":"","institution":"Shanghai Agrobiological Gene Center","correspondingAuthor":true,"submittingAuthor":false,"prefix":"","firstName":"qiaojun","middleName":"","lastName":"lou","suffix":""},{"id":17392453,"identity":"76ef8424-8e35-4abe-94da-d8fbe2785932","order_by":1,"name":"Qingsong Li","email":"","orcid":"","institution":"Shanghai Agrobiological Gene Center","correspondingAuthor":false,"submittingAuthor":false,"prefix":"","firstName":"Qingsong","middleName":"","lastName":"Li","suffix":""},{"id":17392454,"identity":"d189e4f5-5a16-452b-93b0-0743a7fe913a","order_by":2,"name":"Fangjun Feng","email":"","orcid":"","institution":"Shanghai Agrobiological Gene Center","correspondingAuthor":false,"submittingAuthor":false,"prefix":"","firstName":"Fangjun","middleName":"","lastName":"Feng","suffix":""},{"id":17392455,"identity":"bb9662a0-58de-48f9-a851-93c33919332d","order_by":3,"name":"Ryan Joynson","email":"","orcid":"","institution":" Earlham Institute, Norwich Research Park","correspondingAuthor":false,"submittingAuthor":false,"prefix":"","firstName":"Ryan","middleName":"","lastName":"Joynson","suffix":""},{"id":17392456,"identity":"df7132f5-41bf-4e14-abfc-6c56d0d5361a","order_by":4,"name":"Yunan Yang","email":"","orcid":"","institution":"Shanghai Agrobiological Gene Center","correspondingAuthor":false,"submittingAuthor":false,"prefix":"","firstName":"Yunan","middleName":"","lastName":"Yang","suffix":""},{"id":17392457,"identity":"4bd1a89f-aa75-4f0c-b664-465d5efcb00d","order_by":5,"name":"Lijun Luo","email":"","orcid":"","institution":"Shanghai Agrobiological Gene Center","correspondingAuthor":false,"submittingAuthor":false,"prefix":"","firstName":"Lijun","middleName":"","lastName":"Luo","suffix":""},{"id":17392458,"identity":"b1a0b63d-5743-474a-ae0c-ee83de31948a","order_by":6,"name":"Liang Chen","email":"","orcid":"","institution":"Shanghai Agrobiological Gene Center","correspondingAuthor":false,"submittingAuthor":false,"prefix":"","firstName":"Liang","middleName":"","lastName":"Chen","suffix":""}],"badges":[],"createdAt":"2020-08-24 11:50:59","currentVersionCode":2,"declarations":"","doi":"10.21203/rs.3.rs-64873/v2","doiUrl":"https://doi.org/10.21203/rs.3.rs-64873/v2","draftVersion":[],"editorialEvents":[{"content":"https://doi.org/10.1007/s11104-021-05087-5","type":"published","date":"2021-08-28T08:58:28+00:00"}],"editorialNote":"","failedWorkflow":false,"files":[{"id":7117179,"identity":"156dfe2b-02c5-49f3-877c-565f0384d424","added_by":"auto","created_at":"2021-03-18 19:18:58","extension":"jpg","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":3139,"visible":true,"origin":"","legend":" Frequency distribution of gravitropic response speed in the 226 natural rice population. The X axis indicates the first hour’s bending angle of radicle after 90° rotation.","description":"","filename":"ImagefromiOS.jpg","url":"https://assets-eu.researchsquare.com/files/rs-64873/v2/7349211ac019fa160a61e168.jpg"},{"id":7117647,"identity":"c0eaa389-e8cb-4370-96d1-ec5794f93cb3","added_by":"auto","created_at":"2021-03-18 19:21:58","extension":"jpg","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":3139,"visible":true,"origin":"","legend":"Manhattan plots of GWAS of gravitropic response speed. The threshold to declare significance is p=10-5.","description":"","filename":"ImagefromiOS.jpg","url":"https://assets-eu.researchsquare.com/files/rs-64873/v2/a6094a6aab4ace5c2002d0cd.jpg"},{"id":7117180,"identity":"2579a5ed-b597-4d95-b50d-756b130d35e1","added_by":"auto","created_at":"2021-03-18 19:18:58","extension":"jpg","order_by":3,"title":"Figure 3","display":"","copyAsset":false,"role":"figure","size":3139,"visible":true,"origin":"","legend":"Relative expression of 5 candidate genes in 6 extreme rice accessions. The left 3 blue columns indicates the fast gravitropic response varieties named F1, F2 and F3, the right 3 orange columns indicates the slow gravitropic response varieties named S1, S2 and S3.","description":"","filename":"ImagefromiOS.jpg","url":"https://assets-eu.researchsquare.com/files/rs-64873/v2/eb3f60359281d571e08abf85.jpg"},{"id":7117649,"identity":"f233195f-f3ef-45fc-81aa-8d99950582b8","added_by":"auto","created_at":"2021-03-18 19:21:58","extension":"jpg","order_by":4,"title":"Figure 4","display":"","copyAsset":false,"role":"figure","size":3139,"visible":true,"origin":"","legend":"The detailed process of the experiment measuring gravitropic response speed. There are 7 steps to finish the evaluation of gravitropic response speed, and each panel in the figure indicates one step of the method.","description":"","filename":"ImagefromiOS.jpg","url":"https://assets-eu.researchsquare.com/files/rs-64873/v2/c568479fbcea661f1a287b3e.jpg"},{"id":13681481,"identity":"59936b6a-5237-4fc5-ad3b-610b4c5aeb43","added_by":"auto","created_at":"2021-09-17 11:51:57","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":517494,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-64873/v2/31443a52-83c3-4295-b65b-8216948ecc0e.pdf"},{"id":7117648,"identity":"5a227e4f-2310-4395-acf1-d5b7d79a8706","added_by":"auto","created_at":"2021-03-18 19:21:58","extension":"docx","order_by":1,"title":"","display":"","copyAsset":false,"role":"supplement","size":25043,"visible":true,"origin":"","legend":"Supplementary Table 1. The top fast 12 varieties responding gravity in the 226 natural rice population.\nSupplementary Table 2. Primers used in this qPCR.\n","description":"","filename":"additionalfilesrevised.docx","url":"https://assets-eu.researchsquare.com/files/rs-64873/v2/167653e59059aa8a12681b8d.docx"}],"financialInterests":"","formattedTitle":"Evaluation and GWAS of radicle gravitropic response in a core rice germplasms population","fulltext":[{"header":"Introduction","content":"\u003cp\u003eScientists have been trying to understand gravitropism for more than 120 years\u0026nbsp;(Darwin and Darwin 1880). Gravitropism is the orientation of growth in response to gravity, which is necessary for roots to grow into soil, to acquire water and nutrients and to anchor plants, providing stability and preventing lodging.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eThe starch\u0026ndash;statolith hypothesis and the Cholodny\u0026ndash;Went theory attempts to explain some aspects of gravitropism\u0026nbsp;(Haberlandt 1900; Němec 1900; Went 1926; Cholodny N 1927). The starch\u0026ndash;statolith hypothesis proposes that the starch-filled amyloplasts of gravity-sensing cells act as statoliths, signalling the direction of gravity by their sedimentation. The Cholodny\u0026ndash;Went theory indicated, gravity-bending is the result of differential accumulation of auxin on opposite sides of the elongation zone, causing differential growth and tip curvature. In addition, the mechanosensitive ion channel hypothesis also could explain some parts of the gravitropism(Ding and Pickard 1993).\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eMultiple hormones and genes have been found to be involved in gravitropism previously\u0026nbsp;(Blancaflor and Masson 2003; Baldwin et al. 2013; Mai et al. 2014; Ge and Chen 2016; Zhang et al. 2019). Auxin and its related transporters（e.g. AUX1 and AtPIN2）have been observed to regulate gravitropism\u0026nbsp;(Bennett et al. 1996; M\u0026uuml;ller et al. 1998; Rig\u0026oacute; et al. 2013). Cytokinin functions as an anti-gravitropic signaller in lateral roots(Waidmann et al. 2019). Additionally, brassinosteroid also play important role in the root gravitropic response(Kim et al. 2000; Chang et al. 2004; Amzallag and Vaisman 2006). The \u003cem\u003eAGR1\u003c/em\u003e gene involved in root gravitropism could increase root-growth sensitivity to auxin and decrease sensitivity to ethylene in Arabidopsis\u0026nbsp;(Chen et al. 1998). The \u003cem\u003eNPY\u003c/em\u003e genes play an essential role in root gravitropic responses in Arabidopsis(Li et al. 2011). Although the vast majority of research to date has been conducted in \u003cem\u003eArabidopsis thaliana\u003c/em\u003e, few examples of genes affecting gravitropism have been identified in crop species. The organization of the actin cytoskeleton influence the gravitropic response of primary roots of maize\u0026nbsp;(Blancaflor and Hasenstein 1997). Maize \u003cem\u003eLAZY1\u003c/em\u003e mediates shoot gravitropism through regulating auxin transport(Dong et al. 2013).\u003c/p\u003e\n\u003cp\u003eRice is a staple food for nearly half of the world\u0026rsquo;s population. It has a typical fibrous root system. In rice, some mutants and genes related to gravitropism have been identified. \u003cem\u003eLAZY1\u003c/em\u003e gene controls rice shoot gravitropism through regulating polar auxin transport(Li et al. 2007), but the primary roots of \u003cem\u003elazy1\u003c/em\u003e mutants show normal gravitropism and circumnutation\u0026nbsp;(Yoshihara et al. 2013). \u003cem\u003eAem1\u003c/em\u003e mutant causes defects in root development and gravity response\u0026nbsp;(Debi et al. 2005a). Overexpression of \u003cem\u003eOsRAA1\u003c/em\u003e effects root development and root response to gravity(Ge et al. 2004).\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eThe mechanism of gravity sensing in plants is one of the most fascinating questions in molecular biology and because of the new availability of high-throughput sequencing and phenotyping technology, we can expand our knowledge of this trait through association analysis. For example, in the common bean, Liao et al mapped the QTLs controlling basal root\u0026nbsp;gravitropism\u0026nbsp;(Liao et al. 2004). Using a mapping population derived from a Bala \u0026times; Azucena, two main QTLs for gravitropic response have been mapped to chromosome 6 and 11(Norton and Price 2009). Measurement of gravitropism related traits \u0026nbsp; with a throughput lending itself to the sample size required for association analysis is now more feasible with tools such as the ROTATO, an automated camera that could help researchers to dissect the gravity-response(Mullen et al. 2000).\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eDespite progress made in recent decades, processes involved in positive root gravitropic response in the root tip remain largely unclear in rice. Since root gravitropism is widely believed to be regulated by a tipping-point mechanism (Band et al. 2012), the gravitropic response speed could be represented by the bending angle of the seminal in agar-filled Perspex chambers after rotation as Uga et al (Uga et al. 2013) and Norton and Price(Norton and Price 2009) demonstrate. But there are usually large variances among the results of gravitropic response evaluation. \u0026nbsp;To reduce the variance, we had carried out multiple tests to optimise this methodology. \u0026nbsp;Here, using the optimized method we measured gravitropic response speed of an association mapping population consisting 226 core rice accessions and have been in depth studied on drought resistance \u0026nbsp;(Lou et al. 2015; Ma et al. 2016), and identified several QTLs related to gravitropic response that can be deployed into marker assisted selection programmes.\u003c/p\u003e"},{"header":"Results","content":"\u003cp\u003e\u003cstrong\u003eGravitropic response speed of the natural population\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eIn this study, we detected the bending angle of radicle roots of 226 core rice accessions representing their gravitropic response speed (Table1). Among these accessions, the average value of gravitropic response speed of radicle roots was 41.05\u0026deg;/h. The fastest speed was 62.83\u0026deg;/h, meanwhile the slowest speed was 16.77\u0026deg;/h. The standard deviation and coefficient of variation were 6.42\u0026deg;/h and 15.63%, respectively. As shown in \u003cstrong\u003eFig. 1\u003c/strong\u003e, the gravitropic response speed of radicle roots generally presented a normal distribution and was mostly distributed between 31\u0026deg;/h to 51\u0026deg;/h, accounting for 89.4% of the total accessions. This indicated that this set of data was suitable for association mapping analysis of gravitropic response speed of radicle roots. \u0026nbsp;\u003c/p\u003e\n\u003cp style=\"margin-top:0in;margin-right:0in;margin-bottom:8.0pt;margin-left:0in;text-align:justify;line-height:150%;font-size:15px;font-family:DengXian;\"\u003e\u003cspan style='font-size:16px;line-height:150%;font-family:\"Times New Roman\",serif;'\u003e\u0026nbsp;\u003cstrong\u003eTable 1. Gravitropic response speeds of the association mapping population.\u0026nbsp;\u003c/strong\u003eThe\u0026nbsp;\u003c/span\u003e\u003cspan style='font-size:16px;line-height:150%;font-family:\"Times New Roman\",serif;'\u003e\u0026lsquo;\u003c/span\u003e\u003cspan style='font-size:16px;line-height:150%;font-family:\"Times New Roman\",serif;'\u003et-test\u0026rsquo; is value of student\u0026rsquo;s \u0026nbsp;test of the gravitropic response speed between \u003cem\u003eIndica\u0026nbsp;\u003c/em\u003eand \u003cem\u003eJaponica.\u003c/em\u003e\u003c/span\u003e\u003c/p\u003e\n\u003ctable style=\"width:100.0%;border-collapse:collapse;border:none;\"\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd style=\"width:12.42%;border-top:solid windowtext 1.0pt;border-left:none;border-bottom:solid windowtext 1.0pt;border-right:none;padding:.75pt .75pt 0in .75pt;height:38.2pt;\"\u003e\n \u003cp style=\"margin-top:0in;margin-right:0in;margin-bottom:8.0pt;margin-left:0in;text-align:justify;line-height:150%;font-size:15px;font-family:DengXian;\"\u003e\u003cspan style='font-size:13px;line-height:150%;font-family:\"Times New Roman\",serif;'\u003e\u0026nbsp;\u003c/span\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width:13.64%;border-top:solid windowtext 1.0pt;border-left:none;border-bottom:solid windowtext 1.0pt;border-right:none;padding:.75pt .75pt 0in .75pt;height:38.2pt;\"\u003e\n \u003cp style=\"margin-top:0in;margin-right:0in;margin-bottom:8.0pt;margin-left:0in;text-align:center;line-height:150%;font-size:15px;font-family:DengXian;\"\u003e\u003cspan style='font-size:13px;line-height:150%;font-family:\"Times New Roman\",serif;'\u003eNumber of accessions\u003c/span\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width:10.92%;border-top:solid windowtext 1.0pt;border-left:none;border-bottom:solid windowtext 1.0pt;border-right:none;padding:.75pt .75pt 0in .75pt;height:38.2pt;\"\u003e\n \u003cp style=\"margin-top:0in;margin-right:0in;margin-bottom:8.0pt;margin-left:0in;text-align:center;line-height:150%;font-size:15px;font-family:DengXian;\"\u003e\u003cspan style='font-size:13px;line-height:150%;font-family:\"Times New Roman\",serif;'\u003eMeans\u003c/span\u003e\u003cspan style=\"font-size:13px;line-height:150%;font-family:SimSun;\"\u003e（\u003c/span\u003e\u003cspan style='font-size:13px;line-height:150%;font-family: \"Times New Roman\",serif;'\u003e\u0026deg;/h\u003c/span\u003e\u003cspan style=\"font-size:13px;line-height:150%;font-family:SimSun;\"\u003e）\u003c/span\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width:13.5%;border-top:solid windowtext 1.0pt;border-left:none;border-bottom:solid windowtext 1.0pt;border-right:none;padding:.75pt .75pt 0in .75pt;height:38.2pt;\"\u003e\n \u003cp style=\"margin-top:0in;margin-right:0in;margin-bottom:8.0pt;margin-left:0in;text-align:center;line-height:150%;font-size:15px;font-family:DengXian;\"\u003e\u003cspan style='font-size:13px;line-height:150%;font-family:\"Times New Roman\",serif;'\u003eRange\u003c/span\u003e\u003cspan style=\"font-size:13px;line-height:150%;font-family:SimSun;\"\u003e（\u003c/span\u003e\u003cspan style='font-size:13px;line-height:150%;font-family: \"Times New Roman\",serif;'\u003e\u0026deg;/h\u003c/span\u003e\u003cspan style=\"font-size:13px;line-height:150%;font-family:SimSun;\"\u003e）\u003c/span\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width:13.78%;border-top:solid windowtext 1.0pt;border-left:none;border-bottom:solid windowtext 1.0pt;border-right:none;padding:.75pt .75pt 0in .75pt;height:38.2pt;\"\u003e\n \u003cp style=\"margin-top:0in;margin-right:0in;margin-bottom:8.0pt;margin-left:0in;text-align:center;line-height:150%;font-size:15px;font-family:DengXian;\"\u003e\u003cspan style='font-size:13px;line-height:150%;font-family:\"Times New Roman\",serif;'\u003eStandard deviation\u003c/span\u003e\u003cspan style=\"font-size:13px;line-height:150%;font-family:SimSun;\"\u003e（\u003c/span\u003e\u003cspan style='font-size:13px;line-height:150%;font-family:\"Times New Roman\",serif;'\u003eSD, \u0026deg;/h\u003c/span\u003e\u003cspan style=\"font-size:13px;line-height:150%;font-family:SimSun;\"\u003e）\u003c/span\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width:17.86%;border-top:solid windowtext 1.0pt;border-left:none;border-bottom:solid windowtext 1.0pt;border-right:none;padding:.75pt .75pt 0in .75pt;height:38.2pt;\"\u003e\n \u003cp style=\"margin-top:0in;margin-right:0in;margin-bottom:8.0pt;margin-left:0in;text-align:center;line-height:150%;font-size:15px;font-family:DengXian;\"\u003e\u003cspan style='font-size:13px;line-height:150%;font-family:\"Times New Roman\",serif;'\u003eCoefficient variation (CV, %)\u003c/span\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width:17.86%;border-top:solid windowtext 1.0pt;border-left:none;border-bottom:solid windowtext 1.0pt;border-right:none;padding:0in 0in 0in 0in;height:38.2pt;\"\u003e\n \u003cp style=\"margin-top:0in;margin-right:0in;margin-bottom:8.0pt;margin-left:0in;text-align:center;line-height:150%;font-size:15px;font-family:DengXian;\"\u003e\u003cspan style='font-size:13px;line-height:150%;font-family:\"Times New Roman\",serif;'\u003et-test\u003c/span\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width:12.42%;border:none;padding:.75pt .75pt 0in .75pt;height:32.15pt;\"\u003e\n \u003cp style=\"margin-top:0in;margin-right:0in;margin-bottom:8.0pt;margin-left:0in;text-align:center;line-height:150%;font-size:15px;font-family:DengXian;\"\u003e\u003cem\u003e\u003cspan style='font-size:13px;line-height:150%;font-family:\"Times New Roman\",serif;'\u003eIndica\u003c/span\u003e\u003c/em\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width:13.64%;border:none;padding:.75pt .75pt 0in .75pt;height:32.15pt;\"\u003e\n \u003cp style=\"margin-top:0in;margin-right:0in;margin-bottom:8.0pt;margin-left:0in;text-align:center;line-height:150%;font-size:15px;font-family:DengXian;\"\u003e\u003cspan style='font-size:13px;line-height:150%;font-family:\"Times New Roman\",serif;'\u003e133\u003c/span\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width:10.92%;border:none;padding:.75pt .75pt 0in .75pt;height:32.15pt;\"\u003e\n \u003cp style=\"margin-top:0in;margin-right:0in;margin-bottom:8.0pt;margin-left:0in;text-align:center;line-height:150%;font-size:15px;font-family:DengXian;\"\u003e\u003cspan style='font-size:13px;line-height:150%;font-family:\"Times New Roman\",serif;'\u003e42.49\u003c/span\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width:13.5%;border:none;padding:.75pt .75pt 0in .75pt;height:32.15pt;\"\u003e\n \u003cp style=\"margin-top:0in;margin-right:0in;margin-bottom:8.0pt;margin-left:0in;text-align:center;line-height:150%;font-size:15px;font-family:DengXian;\"\u003e\u003cspan style='font-size:13px;line-height:150%;font-family:\"Times New Roman\",serif;'\u003e16.77-62.83\u003c/span\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width:13.78%;border:none;padding:.75pt .75pt 0in .75pt;height:32.15pt;\"\u003e\n \u003cp style=\"margin-top:0in;margin-right:0in;margin-bottom:8.0pt;margin-left:0in;text-align:center;line-height:150%;font-size:15px;font-family:DengXian;\"\u003e\u003cspan style='font-size:13px;line-height:150%;font-family:\"Times New Roman\",serif;'\u003e6.41\u003c/span\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width:17.86%;border:none;padding:.75pt .75pt 0in .75pt;height:32.15pt;\"\u003e\n \u003cp style=\"margin-top:0in;margin-right:0in;margin-bottom:8.0pt;margin-left:0in;text-align:center;line-height:150%;font-size:15px;font-family:DengXian;\"\u003e\u003cspan style='font-size:13px;line-height:150%;font-family:\"Times New Roman\",serif;'\u003e15.32\u003c/span\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd rowspan=\"2\" style=\"width:17.86%;border:none;border-bottom:solid windowtext 1.0pt;padding:0in 0in 0in 0in;height:32.15pt;\"\u003e\n \u003cp style=\"margin-top:0in;margin-right:0in;margin-bottom:8.0pt;margin-left:0in;text-align:center;line-height:150%;font-size:15px;font-family:DengXian;\"\u003e\u003cspan style='font-size:13px;line-height:150%;font-family:\"Times New Roman\",serif;'\u003e0.002\u003c/span\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width:12.42%;border:none;border-bottom:solid windowtext 1.0pt;padding:.75pt .75pt 0in .75pt;height:32.15pt;\"\u003e\n \u003cp style=\"margin-top:0in;margin-right:0in;margin-bottom:8.0pt;margin-left:0in;text-align:center;line-height:150%;font-size:15px;font-family:DengXian;\"\u003e\u003cem\u003e\u003cspan style='font-size:13px;line-height:150%;font-family:\"Times New Roman\",serif;'\u003eJaponica\u003c/span\u003e\u003c/em\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width:13.64%;border:none;border-bottom:solid windowtext 1.0pt;padding:.75pt .75pt 0in .75pt;height:32.15pt;\"\u003e\n \u003cp style=\"margin-top:0in;margin-right:0in;margin-bottom:8.0pt;margin-left:0in;text-align:center;line-height:150%;font-size:15px;font-family:DengXian;\"\u003e\u003cspan style='font-size:13px;line-height:150%;font-family:\"Times New Roman\",serif;'\u003e93\u003c/span\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width:10.92%;border:none;border-bottom:solid windowtext 1.0pt;padding:.75pt .75pt 0in .75pt;height:32.15pt;\"\u003e\n \u003cp style=\"margin-top:0in;margin-right:0in;margin-bottom:8.0pt;margin-left:0in;text-align:center;line-height:150%;font-size:15px;font-family:DengXian;\"\u003e\u003cspan style='font-size:13px;line-height:150%;font-family:\"Times New Roman\",serif;'\u003e39.71\u003c/span\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width:13.5%;border:none;border-bottom:solid windowtext 1.0pt;padding:.75pt .75pt 0in .75pt;height:32.15pt;\"\u003e\n \u003cp style=\"margin-top:0in;margin-right:0in;margin-bottom:8.0pt;margin-left:0in;text-align:center;line-height:150%;font-size:15px;font-family:DengXian;\"\u003e\u003cspan style='font-size:13px;line-height:150%;font-family:\"Times New Roman\",serif;'\u003e21.73-61.64\u003c/span\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width:13.78%;border:none;border-bottom:solid windowtext 1.0pt;padding:.75pt .75pt 0in .75pt;height:32.15pt;\"\u003e\n \u003cp style=\"margin-top:0in;margin-right:0in;margin-bottom:8.0pt;margin-left:0in;text-align:center;line-height:150%;font-size:15px;font-family:DengXian;\"\u003e\u003cspan style='font-size:13px;line-height:150%;font-family:\"Times New Roman\",serif;'\u003e6.30\u003c/span\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width:17.86%;border:none;border-bottom:solid windowtext 1.0pt;padding:.75pt .75pt 0in .75pt;height:32.15pt;\"\u003e\n \u003cp style=\"margin-top:0in;margin-right:0in;margin-bottom:8.0pt;margin-left:0in;text-align:center;line-height:150%;font-size:15px;font-family:DengXian;\"\u003e\u003cspan style='font-size:13px;line-height:150%;font-family:\"Times New Roman\",serif;'\u003e15.77\u003c/span\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width:12.42%;border:none;border-bottom:solid windowtext 1.0pt;padding:.75pt .75pt 0in .75pt;height:32.15pt;\"\u003e\n \u003cp style=\"margin-top:0in;margin-right:0in;margin-bottom:8.0pt;margin-left:0in;text-align:center;line-height:150%;font-size:15px;font-family:DengXian;\"\u003e\u003cspan style='font-size:13px;line-height:150%;font-family:\"Times New Roman\",serif;'\u003eTotal\u003c/span\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width:13.64%;border:none;border-bottom:solid windowtext 1.0pt;padding:.75pt .75pt 0in .75pt;height:32.15pt;\"\u003e\n \u003cp style=\"margin-top:0in;margin-right:0in;margin-bottom:8.0pt;margin-left:0in;text-align:center;line-height:150%;font-size:15px;font-family:DengXian;\"\u003e\u003cspan style='font-size:13px;line-height:150%;font-family:\"Times New Roman\",serif;'\u003e226\u003c/span\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width:10.92%;border:none;border-bottom:solid windowtext 1.0pt;padding:.75pt .75pt 0in .75pt;height:32.15pt;\"\u003e\n \u003cp style=\"margin-top:0in;margin-right:0in;margin-bottom:8.0pt;margin-left:0in;text-align:center;line-height:150%;font-size:15px;font-family:DengXian;\"\u003e\u003cspan style='font-size:13px;line-height:150%;font-family:\"Times New Roman\",serif;'\u003e41.05\u003c/span\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width:13.5%;border:none;border-bottom:solid windowtext 1.0pt;padding:.75pt .75pt 0in .75pt;height:32.15pt;\"\u003e\n \u003cp style=\"margin-top:0in;margin-right:0in;margin-bottom:8.0pt;margin-left:0in;text-align:center;line-height:150%;font-size:15px;font-family:DengXian;\"\u003e\u003cspan style='font-size:13px;line-height:150%;font-family:\"Times New Roman\",serif;'\u003e62.83-16.77\u003c/span\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width:13.78%;border:none;border-bottom:solid windowtext 1.0pt;padding:.75pt .75pt 0in .75pt;height:32.15pt;\"\u003e\n \u003cp style=\"margin-top:0in;margin-right:0in;margin-bottom:8.0pt;margin-left:0in;text-align:justify;line-height:150%;font-size:15px;font-family:DengXian;\"\u003e\u003cspan style='font-size:13px;line-height:150%;font-family:\"Times New Roman\",serif;'\u003e\u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; 6.42\u0026nbsp;\u003c/span\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width:17.86%;border:none;border-bottom:solid windowtext 1.0pt;padding:.75pt .75pt 0in .75pt;height:32.15pt;\"\u003e\n \u003cp style=\"margin-top:0in;margin-right:0in;margin-bottom:8.0pt;margin-left:0in;text-align:center;line-height:150%;font-size:15px;font-family:DengXian;\"\u003e\u003cspan style='font-size:13px;line-height:150%;font-family:\"Times New Roman\",serif;'\u003e15.63\u003c/span\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 17.86%;border-top: none;border-right: none;border-left: none;border-image: initial;border-bottom: 1pt solid windowtext;padding: 0in;height: 32.15pt;vertical-align: top;\"\u003e\n \u003cp style=\"margin-top:0in;margin-right:0in;margin-bottom:8.0pt;margin-left:0in;text-align:center;line-height:150%;font-size:15px;font-family:DengXian;\"\u003e\u003cspan style='font-size:13px;line-height:150%;font-family:\"Times New Roman\",serif;'\u003e\u0026nbsp;\u003c/span\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n\u003c/table\u003e\n\u003cp\u003eNotable differences of gravitropic response speed were found between \u003cem\u003eIndica\u003c/em\u003e and \u003cem\u003eJaponica\u003c/em\u003e rice (\u003cstrong\u003eTable1\u003c/strong\u003e). The gravitropic response speed of \u003cem\u003eIndica\u0026nbsp;\u003c/em\u003erice was mostly distributed between 33.5\u0026deg;/h to 53.5\u0026deg;/h, accounting for 94.7% of the \u003cem\u003eIndica\u003c/em\u003e accessions. As for the \u003cem\u003eJaponica\u003c/em\u003e rice, it was mostly distributed at 33.5\u0026deg;/h to 48.5\u0026deg;/h, accounting for 90.3% of the \u003cem\u003eJaponica\u003c/em\u003e accessions. \u0026nbsp;The mean of gravitropic response speed of \u003cem\u003eIndica\u003c/em\u003e (42.49\u0026deg;/h) was faster than that of \u003cem\u003eJaponica\u003c/em\u003e (39.71\u0026deg;/h). Likewise, the range of variation in \u003cem\u003eIndica\u003c/em\u003e (46.06\u0026deg;/h) was larger than that in \u003cem\u003eJaponica\u003c/em\u003e (39.91\u0026deg;/h)\u003cem\u003e.\u0026nbsp;\u003c/em\u003eThe standard deviation and coefficient of variation of \u003cem\u003eIndica\u003c/em\u003e and \u003cem\u003eJaponica\u003c/em\u003e accessions were 6.41\u0026deg;/h and 6.30\u0026deg;/h, 15.32% and 15.77%, respectively. Compared the gravitropic response speed of \u003cem\u003eIndica\u003c/em\u003e and \u003cem\u003eJaponica\u003c/em\u003e rice by student\u0026rsquo;s (t) test resulted in a p value of inequality at 0.002. This result suggested that there was significant difference in the gravitropic response speed between \u003cem\u003eIndica\u003c/em\u003e and \u003cem\u003eJaponica\u0026nbsp;\u003c/em\u003esubspecies, and the gravity response speed of\u003cem\u003e\u0026nbsp;Indica\u003c/em\u003e radicle roots was significantly faster than that of\u003cem\u003e\u0026nbsp;Japonica\u003c/em\u003e rice.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eCorrelation among gravitropic response speed, deep rooting phenotype and drought resistant index\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eMultiple measurements for root phenotypes of these 226 accessions have been measured in an our previous study\u0026nbsp;(Lou et al. 2015)\u0026nbsp;. The ratio of the yield in dry fields to the yield in paddy fields was calculated as the yield-based drought resistant index (DRI). The original data of DRI was obtained from a previous study in our laboratory(Ma et al. 2016). Correlations were calculated between these measurements and the gravitropic response measurements to determine if these traits could be inherently linked. By comparing the correlation coefficient between gravitropic response speed and some agronomic traits (\u003cstrong\u003eTable 2\u003c/strong\u003e), we observed that the gravitropic response speed was significantly positively correlated with tiller number (TN), deep roots (DR), growth speed of radicle roots (GSR) and drought resistant index (DRI) with correlation coefficients of 0.13, 0.16, 0.22 and 0.14, respectively. The results indicated that the speed of the gravitropic response of radicle roots was highly significantly positively correlated with the speed of radicle roots growth. The faster the gravitropic response, the faster the growth speed. At significance level \u0026alpha;=0.05, the speed of the gravitropic response of radicle roots was also positively correlated with TN, DR and DRI. The faster the response speed, the larger the deep roots number as well as the drought resistant index. There was no significant correlation between the speed of gravitropic response and plant height (PH), shallow roots (SR), ratio of deep roots (RDR) or roots per tiller (R/T).\u0026nbsp;\u003c/p\u003e\n\u003cp style=\"margin-top:0in;margin-right:0in;margin-bottom:0in;margin-left:0in;text-align:justify;line-height:normal;font-size:15px;font-family:DengXian;\"\u003e\u003cstrong\u003e\u003cspan style='font-size:16px;font-family:\"Times New Roman\",serif;'\u003eTable 2. Correlation coefficient between gravitropic response speed and some agronomic traits\u003c/span\u003e\u003c/strong\u003e\u003c/p\u003e\n\u003ctable style=\"width: 2.5e+2pt;border: none;border-collapse:collapse;\"\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd style=\"width:170.2pt;border-top:solid windowtext 1.0pt;border-left:none;border-bottom:solid windowtext 1.0pt;border-right:none;padding:.75pt .75pt 0in .75pt;height:32.7pt;\"\u003e\n \u003cp style=\"margin-top:0in;margin-right:0in;margin-bottom:0in;margin-left:0in;text-align:center;line-height:normal;font-size:15px;font-family:DengXian;\"\u003e\u003cspan style='font-size:16px;font-family:\"Times New Roman\",serif;'\u003e\u0026nbsp;\u003c/span\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"2\" style=\"width:78.0pt;border-top:solid windowtext 1.0pt;border-left:none;border-bottom:solid windowtext 1.0pt;border-right:none;padding:.75pt .75pt 0in .75pt;height:32.7pt;\"\u003e\n \u003cp style=\"margin-top:0in;margin-right:0in;margin-bottom:0in;margin-left:0in;text-align:left;line-height:normal;font-size:15px;font-family:DengXian;\"\u003e\u003cspan style='font-size:16px;font-family:\"Times New Roman\",serif;'\u003eBending angle of radicle\u003c/span\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd colspan=\"2\" style=\"width:177.2pt;padding:.75pt .75pt 0in .75pt;height:17.0pt;\"\u003e\n \u003cp style=\"margin-top:0in;margin-right:0in;margin-bottom:0in;margin-left:0in;text-align:left;line-height:normal;font-size:15px;font-family:DengXian;\"\u003e\u003cspan style='font-size:16px;font-family:\"Times New Roman\",serif;'\u003ePlant height (PH)\u003c/span\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width:70.9pt;padding:.75pt .75pt 0in .75pt;height:17.0pt;\"\u003e\n \u003cp style=\"margin-top:0in;margin-right:0in;margin-bottom:0in;margin-left:0in;text-align:left;line-height:normal;font-size:15px;font-family:DengXian;\"\u003e\u003cspan style='font-size:16px;font-family: \"Times New Roman\",serif;'\u003e0.03\u003c/span\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd colspan=\"2\" style=\"width:177.2pt;padding:.75pt .75pt 0in .75pt;height:17.0pt;\"\u003e\n \u003cp style=\"margin-top:0in;margin-right:0in;margin-bottom:0in;margin-left:0in;text-align:left;line-height:normal;font-size:15px;font-family:DengXian;\"\u003e\u003cspan style='font-size:16px;font-family: \"Times New Roman\",serif;'\u003eTiller number (TN)\u003c/span\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width:70.9pt;padding:.75pt .75pt 0in .75pt;height:17.0pt;\"\u003e\n \u003cp style=\"margin-top:0in;margin-right:0in;margin-bottom:0in;margin-left:0in;text-align:left;line-height:normal;font-size:15px;font-family:DengXian;\"\u003e\u003cspan style='font-size:16px;font-family: \"Times New Roman\",serif;'\u003e0.13\u003csup\u003e*\u003c/sup\u003e\u003c/span\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd colspan=\"2\" style=\"width:177.2pt;padding:.75pt .75pt 0in .75pt;height:17.0pt;\"\u003e\n \u003cp style=\"margin-top:0in;margin-right:0in;margin-bottom:0in;margin-left:0in;text-align:left;line-height:normal;font-size:15px;font-family:DengXian;\"\u003e\u003cspan style='font-size:16px;font-family: \"Times New Roman\",serif;'\u003eDeep roots number (DR)\u003c/span\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width:70.9pt;padding:.75pt .75pt 0in .75pt;height:17.0pt;\"\u003e\n \u003cp style=\"margin-top:0in;margin-right:0in;margin-bottom:0in;margin-left:0in;text-align:left;line-height:normal;font-size:15px;font-family:DengXian;\"\u003e\u003cspan style='font-size:16px;font-family: \"Times New Roman\",serif;'\u003e0.16\u003csup\u003e*\u003c/sup\u003e\u003c/span\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd colspan=\"2\" style=\"width:177.2pt;padding:.75pt .75pt 0in .75pt;height:17.0pt;\"\u003e\n \u003cp style=\"margin-top:0in;margin-right:0in;margin-bottom:0in;margin-left:0in;text-align:left;line-height:normal;font-size:15px;font-family:DengXian;\"\u003e\u003cspan style='font-size:16px;font-family: \"Times New Roman\",serif;'\u003eShallow roots number (SR)\u003c/span\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width:70.9pt;padding:.75pt .75pt 0in .75pt;height:17.0pt;\"\u003e\n \u003cp style=\"margin-top:0in;margin-right:0in;margin-bottom:0in;margin-left:0in;text-align:left;line-height:normal;font-size:15px;font-family:DengXian;\"\u003e\u003cspan style='font-size:16px;font-family: \"Times New Roman\",serif;'\u003e0.09\u003c/span\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd colspan=\"2\" style=\"width:177.2pt;padding:.75pt .75pt 0in .75pt;height:17.0pt;\"\u003e\n \u003cp style=\"margin-top:0in;margin-right:0in;margin-bottom:0in;margin-left:0in;text-align:left;line-height:normal;font-size:15px;font-family:DengXian;\"\u003e\u003cspan style='font-size:16px;font-family: \"Times New Roman\",serif;'\u003eTotal roots number (TR)\u003c/span\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width:70.9pt;padding:.75pt .75pt 0in .75pt;height:17.0pt;\"\u003e\n \u003cp style=\"margin-top:0in;margin-right:0in;margin-bottom:0in;margin-left:0in;text-align:left;line-height:normal;font-size:15px;font-family:DengXian;\"\u003e\u003cspan style='font-size:16px;font-family: \"Times New Roman\",serif;'\u003e0.12\u003c/span\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd colspan=\"2\" style=\"width:177.2pt;padding:.75pt .75pt 0in .75pt;height:17.0pt;\"\u003e\n \u003cp style=\"margin-top:0in;margin-right:0in;margin-bottom:0in;margin-left:0in;text-align:left;line-height:normal;font-size:15px;font-family:DengXian;\"\u003e\u003cspan style='font-size:16px;font-family: \"Times New Roman\",serif;'\u003eRatio of deep roots (RDR)\u003c/span\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width:70.9pt;padding:.75pt .75pt 0in .75pt;height:17.0pt;\"\u003e\n \u003cp style=\"margin-top:0in;margin-right:0in;margin-bottom:0in;margin-left:0in;text-align:left;line-height:normal;font-size:15px;font-family:DengXian;\"\u003e\u003cspan style='font-size:16px;font-family: \"Times New Roman\",serif;'\u003e0.05\u003c/span\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd colspan=\"2\" style=\"width:177.2pt;padding:.75pt .75pt 0in .75pt;height:17.0pt;\"\u003e\n \u003cp style=\"margin-top:0in;margin-right:0in;margin-bottom:0in;margin-left:0in;text-align:left;line-height:normal;font-size:15px;font-family:DengXian;\"\u003e\u003cspan style='font-size:16px;font-family: \"Times New Roman\",serif;'\u003eRoots per tiller (R/T)\u003c/span\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width:70.9pt;padding:.75pt .75pt 0in .75pt;height:17.0pt;\"\u003e\n \u003cp style=\"margin-top:0in;margin-right:0in;margin-bottom:0in;margin-left:0in;text-align:left;line-height:normal;font-size:15px;font-family:DengXian;\"\u003e\u003cspan style='font-size:16px;font-family: \"Times New Roman\",serif;'\u003e0.01\u003c/span\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd colspan=\"2\" style=\"width:177.2pt;padding:.75pt .75pt 0in .75pt;height:17.0pt;\"\u003e\n \u003cp style=\"margin-top:0in;margin-right:0in;margin-bottom:0in;margin-left:0in;text-align:left;line-height:normal;font-size:15px;font-family:DengXian;\"\u003e\u003cspan style='font-size:16px;font-family: \"Times New Roman\",serif;'\u003eGrowth speed of radicle (GSR)\u003c/span\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width:70.9pt;padding:.75pt .75pt 0in .75pt;height:17.0pt;\"\u003e\n \u003cp style=\"margin-top:0in;margin-right:0in;margin-bottom:0in;margin-left:0in;text-align:left;line-height:normal;font-size:15px;font-family:DengXian;\"\u003e\u003cspan style='font-size:16px;font-family: \"Times New Roman\",serif;'\u003e0.22\u003csup\u003e**\u003c/sup\u003e\u003c/span\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd colspan=\"2\" style=\"width:177.2pt;border:none;border-bottom: solid windowtext 1.0pt;padding:.75pt .75pt 0in .75pt;height:17.0pt;\"\u003e\n \u003cp style=\"margin-top:0in;margin-right:0in;margin-bottom:0in;margin-left:0in;text-align:left;line-height:normal;font-size:15px;font-family:DengXian;\"\u003e\u003cspan style='font-size:16px;font-family: \"Times New Roman\",serif;'\u003eDrought resistant index (DRI)\u003c/span\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width:70.9pt;border:none;border-bottom:solid windowtext 1.0pt;padding:.75pt .75pt 0in .75pt;height:17.0pt;\"\u003e\n \u003cp style=\"margin-top:0in;margin-right:0in;margin-bottom:0in;margin-left:0in;text-align:left;line-height:normal;font-size:15px;font-family:DengXian;\"\u003e\u003cspan style='font-size:16px;font-family: \"Times New Roman\",serif;'\u003e0.14\u003csup\u003e*\u003c/sup\u003e\u003c/span\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"border:none;\"\u003e\u003cbr\u003e\u003c/td\u003e\n \u003ctd style=\"border:none;\"\u003e\u003cbr\u003e\u003c/td\u003e\n \u003ctd style=\"border:none;\"\u003e\u003cbr\u003e\u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n\u003c/table\u003e\n\u003cp style=\"margin-top:0in;margin-right:0in;margin-bottom:8.0pt;margin-left:0in;text-align:justify;line-height:normal;font-size:15px;font-family:DengXian;\"\u003e\u003cspan style='font-size:16px;font-family:\"Times New Roman\",serif;'\u003eNote: \u0026ldquo;*\u0026rdquo; means significance at P\u0026lt;0.05, \u0026ldquo;**\u0026rdquo; means significance at P\u0026lt;0.01.\u003c/span\u003e\u003c/p\u003e\n\u003cp\u003eThen, 12 accessions with the fastest speed of gravitropic response were selected for further study, and the growth speed of radicle roots and DRI of this subset were measured (\u003cstrong\u003eSupplementary Table 1)\u003c/strong\u003e. Among them, the DRI of Xiaohonggu, IAC1246 and Zaohandao was 1.06, 1.18 and 1.89, respectively. These 3 accessions could be chosen as donor parental lines for drought-resistant breeding in the future.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eGWAS of the gravitropic response speed of radicle roots\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe raw sequence data of this population have been uploaded to public databases: http://www.ncbi.nlm.nih.gov/bioproject/PRJNA260762 and ftp://ftp-trace.ncbi.nlm.nih.gov/sra/sra-instant/reads/ByRun/sra/SRR/SRR123/SRR12 39601(Lou et al. 2015). GWAS was carried out to associate gravitropic response speed to a responsible genomic location using the EMMA model. 3 significantly associated QTLs were detected at the threshold of p=10\u003csup\u003e-5\u003c/sup\u003e (\u003cstrong\u003eFig. 2\u003c/strong\u003e, \u003cstrong\u003eTable 3\u003c/strong\u003e). A QTL named \u003cem\u003eqGRS4\u0026nbsp;\u003c/em\u003ewas mapped on the chromosome 4 (4774373bp), and other 2 QTLs named \u003cem\u003eqGRS11\u0026nbsp;\u003c/em\u003eand\u003cem\u003e\u0026nbsp;qGRS12\u0026nbsp;\u003c/em\u003elocated on each of chromosomes 11 and 12 (23451244bp and 17439378bp, respectively).\u0026nbsp;\u003c/p\u003e\n\u003cp style=\"margin-top:0in;margin-right:0in;margin-bottom:0in;margin-left:0in;text-align:left;line-height:normal;font-size:15px;font-family:DengXian;\"\u003e\u003cstrong\u003e\u003cspan style='font-size:16px;font-family:\"Times New Roman\",serif;'\u003eTable 3\u003c/span\u003e\u003c/strong\u003e\u003cstrong\u003e\u003cspan style='font-size:16px;font-family:\"Times New Roman\",serif;'\u003e.\u003c/span\u003e\u003c/strong\u003e\u003cstrong\u003e\u003cspan style='font-size:16px;font-family:\"Times New Roman\",serif;'\u003e\u0026nbsp;SNP loci related to gravitational response identified by GWAS\u003c/span\u003e\u003c/strong\u003e\u003c/p\u003e\n\u003cdiv align=\"center\" style=\"margin-top:0in;margin-right:0in;margin-bottom:8.0pt;margin-left:0in;text-align:justify;line-height:107%;font-size:15px;font-family:DengXian;\"\u003e\n \u003ctable style=\"border: none;width:100.0%;border-collapse:collapse;\"\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd style=\"width:7.48%;border-top:solid black 1.0pt;border-left:none;border-bottom:solid black 1.0pt;border-right:none;padding:.75pt .75pt 0in .75pt;height:24.65pt;\"\u003e\n \u003cp style=\"margin-top:0in;margin-right:0in;margin-bottom:0in;margin-left:0in;text-align:center;line-height:normal;font-size:15px;font-family:DengXian;\"\u003e\u003cspan style='font-size:16px;font-family:\"Times New Roman\",serif;'\u003eNO.\u003c/span\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width:14.08%;border-top:solid black 1.0pt;border-left: none;border-bottom:solid black 1.0pt;border-right:none;padding:0in 0in 0in 0in;height:24.65pt;\"\u003e\n \u003cp style=\"margin-top:0in;margin-right:0in;margin-bottom:0in;margin-left:0in;text-align:center;line-height:normal;font-size:15px;font-family:DengXian;\"\u003e\u003cspan style='font-size:16px;font-family:\"Times New Roman\",serif;'\u003eQTL\u003c/span\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width:17.58%;border-top:solid black 1.0pt;border-left:none;border-bottom:solid black 1.0pt;border-right:none;padding:.75pt .75pt 0in .75pt;height:24.65pt;\"\u003e\n \u003cp style=\"margin-top:0in;margin-right:0in;margin-bottom:0in;margin-left:0in;text-align:center;line-height:normal;font-size:15px;font-family:DengXian;\"\u003e\u003cspan style='font-size:16px;font-family:\"Times New Roman\",serif;'\u003eLead SNP\u0026nbsp;\u003c/span\u003e\u003cspan style='font-size:16px;font-family:\"Times New Roman\",serif;'\u003e(bp)\u003c/span\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width:15.94%;border-top:solid black 1.0pt;border-left:none;border-bottom:solid black 1.0pt;border-right:none;padding:.75pt .75pt 0in .75pt;height:24.65pt;\"\u003e\n \u003cp style=\"margin-top:0in;margin-right:0in;margin-bottom:0in;margin-left:0in;text-align:center;line-height:normal;font-size:15px;font-family:DengXian;\"\u003e\u003cspan style='font-size:16px;font-family:\"Times New Roman\",serif;'\u003eChr\u003c/span\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 8.04%;border-top: 1pt solid black;border-left: none;border-bottom: 1pt solid black;border-right: none;padding: 0in;height: 24.65pt;vertical-align: top;\"\u003e\n \u003cp style=\"margin-top:6.0pt;margin-right:0in;margin-bottom:0in;margin-left:0in;text-align:center;line-height:normal;font-size:15px;font-family:DengXian;\"\u003e\u003cspan style='font-size:16px;font-family:\"Times New Roman\",serif;'\u003eMaf\u003c/span\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width:25.86%;border-top:solid black 1.0pt;border-left:none;border-bottom:solid black 1.0pt;border-right:none;padding:.75pt .75pt 0in .75pt;height:24.65pt;\"\u003e\n \u003cp style=\"margin-top:0in;margin-right:0in;margin-bottom:0in;margin-left:0in;text-align:center;line-height:normal;font-size:15px;font-family:DengXian;\"\u003e\u003cspan style='font-size:16px;font-family:\"Times New Roman\",serif;'\u003eLD\u0026nbsp;\u003c/span\u003e\u003cspan style='font-size:16px;font-family: \"Times New Roman\",serif;'\u003eRange\u003c/span\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width:11.0%;border-top:solid black 1.0pt;border-left: none;border-bottom:solid black 1.0pt;border-right:none;padding:0in 0in 0in 0in;height:24.65pt;\"\u003e\n \u003cp style=\"margin-top:0in;margin-right:0in;margin-bottom:0in;margin-left:0in;text-align:center;line-height:normal;font-size:15px;font-family:DengXian;\"\u003e\u003cspan style='font-size:16px;font-family:\"Times New Roman\",serif;'\u003eP value\u003c/span\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width:7.48%;padding:.75pt .75pt 0in .75pt;height:23.1pt;\"\u003e\n \u003cp style=\"margin-top:0in;margin-right:0in;margin-bottom:0in;margin-left:0in;text-align:center;line-height:normal;font-size:15px;font-family:DengXian;\"\u003e\u003cspan style='font-size:16px;font-family:\"Times New Roman\",serif;'\u003e1\u003c/span\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width:14.08%;padding:0in 0in 0in 0in;height:23.1pt;\"\u003e\n \u003cp style=\"margin-top:0in;margin-right:0in;margin-bottom:0in;margin-left:0in;text-align:center;line-height:normal;font-size:15px;font-family:DengXian;\"\u003e\u003cem\u003e\u003cspan style='font-size:16px;font-family:\"Times New Roman\",serif;'\u003eqGRS4\u003c/span\u003e\u003c/em\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width:17.58%;padding:.75pt .75pt 0in .75pt;height:23.1pt;\"\u003e\n \u003cp style=\"margin-top:0in;margin-right:0in;margin-bottom:0in;margin-left:0in;text-align:center;line-height:normal;font-size:15px;font-family:DengXian;\"\u003e\u003cspan style='font-size:16px;font-family:\"Times New Roman\",serif;'\u003e404774373\u003c/span\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width:15.94%;padding:.75pt .75pt 0in .75pt;height:23.1pt;\"\u003e\n \u003cp style=\"margin-top:0in;margin-right:0in;margin-bottom:0in;margin-left:0in;text-align:center;line-height:normal;font-size:15px;font-family:DengXian;\"\u003e\u003cspan style='font-size:16px;font-family:\"Times New Roman\",serif;'\u003e4\u003c/span\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 8.04%;padding: 0in;height: 23.1pt;vertical-align: top;\"\u003e\n \u003cp style=\"margin-top:6.0pt;margin-right:0in;margin-bottom:0in;margin-left:0in;text-align:center;line-height:normal;font-size:15px;font-family:DengXian;\"\u003e\u003cspan style='font-size:16px;font-family:\"Times New Roman\",serif;'\u003e0.08\u003c/span\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width:25.86%;padding:.75pt .75pt 0in .75pt;height:23.1pt;\"\u003e\n \u003cp style=\"margin-top:0in;margin-right:0in;margin-bottom:0in;margin-left:0in;text-align:center;line-height:normal;font-size:15px;font-family:DengXian;\"\u003e\u003cspan style='font-size:16px;font-family:\"Times New Roman\",serif;'\u003e180Kb\u003c/span\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width:11.0%;padding:0in 0in 0in 0in;height:23.1pt;\"\u003e\n \u003cp style=\"margin-top:0in;margin-right:0in;margin-bottom:0in;margin-left:0in;text-align:center;line-height:normal;font-size:15px;font-family:DengXian;\"\u003e\u003cspan style='font-size:16px;font-family:\"Times New Roman\",serif;'\u003e4.83E-06\u003c/span\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width:7.48%;padding:.75pt .75pt 0in .75pt;height:23.1pt;\"\u003e\n \u003cp style=\"margin-top:0in;margin-right:0in;margin-bottom:0in;margin-left:0in;text-align:center;line-height:normal;font-size:15px;font-family:DengXian;\"\u003e\u003cspan style='font-size:16px;font-family:\"Times New Roman\",serif;'\u003e2\u003c/span\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width:14.08%;padding:0in 0in 0in 0in;height:23.1pt;\"\u003e\n \u003cp style=\"margin-top:0in;margin-right:0in;margin-bottom:0in;margin-left:0in;text-align:center;line-height:normal;font-size:15px;font-family:DengXian;\"\u003e\u003cem\u003e\u003cspan style='font-size:16px;font-family:\"Times New Roman\",serif;'\u003eqGRS11\u003c/span\u003e\u003c/em\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width:17.58%;padding:.75pt .75pt 0in .75pt;height:23.1pt;\"\u003e\n \u003cp style=\"margin-top:0in;margin-right:0in;margin-bottom:0in;margin-left:0in;text-align:center;line-height:normal;font-size:15px;font-family:DengXian;\"\u003e\u003cspan style='font-size:16px;font-family:\"Times New Roman\",serif;'\u003e1123451244\u003c/span\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width:15.94%;padding:.75pt .75pt 0in .75pt;height:23.1pt;\"\u003e\n \u003cp style=\"margin-top:0in;margin-right:0in;margin-bottom:0in;margin-left:0in;text-align:center;line-height:normal;font-size:15px;font-family:DengXian;\"\u003e\u003cspan style='font-size:16px;font-family:\"Times New Roman\",serif;'\u003e11\u003c/span\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 8.04%;padding: 0in;height: 23.1pt;vertical-align: top;\"\u003e\n \u003cp style=\"margin-top:6.0pt;margin-right:0in;margin-bottom:0in;margin-left:0in;text-align:center;line-height:normal;font-size:15px;font-family:DengXian;\"\u003e\u003cspan style='font-size:16px;font-family:\"Times New Roman\",serif;'\u003e0.07\u003c/span\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width:25.86%;padding:.75pt .75pt 0in .75pt;height:23.1pt;\"\u003e\n \u003cp style=\"margin-top:0in;margin-right:0in;margin-bottom:0in;margin-left:0in;text-align:center;line-height:normal;font-size:15px;font-family:DengXian;\"\u003e\u003cspan style='font-size:16px;font-family:\"Times New Roman\",serif;'\u003e580Kb\u003c/span\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width:11.0%;padding:0in 0in 0in 0in;height:23.1pt;\"\u003e\n \u003cp style=\"margin-top:0in;margin-right:0in;margin-bottom:0in;margin-left:0in;text-align:center;line-height:normal;font-size:15px;font-family:DengXian;\"\u003e\u003cspan style='font-size:16px;font-family:\"Times New Roman\",serif;'\u003e7.77E-06\u003c/span\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width:7.48%;border:none;border-bottom:solid windowtext 1.0pt;padding:.75pt .75pt 0in .75pt;height:23.1pt;\"\u003e\n \u003cp style=\"margin-top:0in;margin-right:0in;margin-bottom:0in;margin-left:0in;text-align:center;line-height:normal;font-size:15px;font-family:DengXian;\"\u003e\u003cspan style='font-size:16px;font-family:\"Times New Roman\",serif;'\u003e3\u003c/span\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width:14.08%;border:none;border-bottom:solid windowtext 1.0pt;padding:0in 0in 0in 0in;height:23.1pt;\"\u003e\n \u003cp style=\"margin-top:0in;margin-right:0in;margin-bottom:0in;margin-left:0in;text-align:center;line-height:normal;font-size:15px;font-family:DengXian;\"\u003e\u003cem\u003e\u003cspan style='font-size:16px;font-family:\"Times New Roman\",serif;'\u003eqGRS12\u003c/span\u003e\u003c/em\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width:17.58%;border:none;border-bottom:solid windowtext 1.0pt;padding:.75pt .75pt 0in .75pt;height:23.1pt;\"\u003e\n \u003cp style=\"margin-top:0in;margin-right:0in;margin-bottom:0in;margin-left:0in;text-align:center;line-height:normal;font-size:15px;font-family:DengXian;\"\u003e\u003cspan style='font-size:16px;font-family:\"Times New Roman\",serif;'\u003e1217439378\u003c/span\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width:15.94%;border:none;border-bottom:solid windowtext 1.0pt;padding:.75pt .75pt 0in .75pt;height:23.1pt;\"\u003e\n \u003cp style=\"margin-top:0in;margin-right:0in;margin-bottom:0in;margin-left:0in;text-align:center;line-height:normal;font-size:15px;font-family:DengXian;\"\u003e\u003cspan style='font-size:16px;font-family:\"Times New Roman\",serif;'\u003e12\u003c/span\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 8.04%;border-top: none;border-right: none;border-left: none;border-image: initial;border-bottom: 1pt solid windowtext;padding: 0in;height: 23.1pt;vertical-align: top;\"\u003e\n \u003cp style=\"margin-top:6.0pt;margin-right:0in;margin-bottom:0in;margin-left:0in;text-align:center;line-height:normal;font-size:15px;font-family:DengXian;\"\u003e\u003cspan style='font-size:16px;font-family:\"Times New Roman\",serif;'\u003e0.20\u003c/span\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width:25.86%;border:none;border-bottom:solid windowtext 1.0pt;padding:.75pt .75pt 0in .75pt;height:23.1pt;\"\u003e\n \u003cp style=\"margin-top:0in;margin-right:0in;margin-bottom:0in;margin-left:0in;text-align:center;line-height:normal;font-size:15px;font-family:DengXian;\"\u003e\u003cspan style='font-size:16px;font-family:\"Times New Roman\",serif;'\u003e1Mb\u003c/span\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width:11.0%;border:none;border-bottom:solid windowtext 1.0pt;padding:0in 0in 0in 0in;height:23.1pt;\"\u003e\n \u003cp style=\"margin-top:0in;margin-right:0in;margin-bottom:0in;margin-left:0in;text-align:center;line-height:normal;font-size:15px;font-family:DengXian;\"\u003e\u003cspan style='font-size:16px;font-family:\"Times New Roman\",serif;'\u003e4.87E-06\u003c/span\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n \u003c/table\u003e\n\u003c/div\u003e\n\u003cp style=\"margin-top:0in;margin-right:0in;margin-bottom:0in;margin-left:0in;text-align:left;line-height:normal;font-size:15px;font-family:DengXian;\"\u003e\u003cspan style='font-size:16px;font-family:\"Times New Roman\",serif;'\u003eChr, chromosome; Maf, minor allele frequency;\u003c/span\u003e \u003cspan style='font-size:16px;font-family:\"Times New Roman\",serif;'\u003eLD Range,\u0026nbsp;\u003c/span\u003e\u003cspan style='font-size:16px;font-family:\"Times New Roman\",serif;'\u003elinkage disequilibrium decay distance at r\u003csup\u003e2\u003c/sup\u003e\u0026gt;0.65.\u003c/span\u003e\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eqPCR of candidate genes of gravitropic response\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eAccording to the GWAS results and based on the annotation information from the Rice Genome Annotation Project (http://rice.plantbiology.msu.edu/) and our previous transcriptome data of rice root(Lou et al. 2017),\u0026nbsp;5 candidate genes in close proximity to the most associated SNPs that may relate with roots gravitropic response were chosen for further expression analysis (\u003cstrong\u003eTable 4\u003c/strong\u003e). From Chromosome 4 to 12, they are an ethylene receptor, an A49-like RNA polymerase I associated factor family protein, a GRF-interacting factor 2, a wall-associated receptor kinase-like 2 precursors and an ATP binding protein.\u003c/p\u003e\n\u003cp style=\"margin-top:0in;margin-right:0in;margin-bottom:0in;margin-left:0in;text-align:justify;line-height:normal;font-size:15px;font-family:DengXian;\"\u003e\u003cstrong\u003e\u003cspan style='font-size:16px;font-family:\"Times New Roman\",serif;'\u003eTable 4. Candidate genes of gravitropic response speed and their annotations\u003c/span\u003e\u003c/strong\u003e\u003c/p\u003e\n\u003ctable style=\"width: 4.3e+2pt;border: none;border-collapse:collapse;\"\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd style=\"width:82.65pt;border-top:solid black 1.0pt;border-left:none;border-bottom:solid black 1.0pt;border-right:none;padding:.75pt .75pt 0in .75pt;height:35.65pt;\"\u003e\n \u003cp style=\"margin-top:0in;margin-right:0in;margin-bottom:0in;margin-left:0in;text-align:center;line-height:normal;font-size:15px;font-family:DengXian;\"\u003e\u003cspan style='font-size:16px;font-family:\"Times New Roman\",serif;'\u003eQTL\u003c/span\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width:1.45in;border-top:solid black 1.0pt;border-left: none;border-bottom:solid black 1.0pt;border-right:none;padding:.75pt .75pt 0in .75pt;height:35.65pt;\"\u003e\n \u003cp style=\"margin-top:0in;margin-right:0in;margin-bottom:0in;margin-left:0in;text-align:center;line-height:normal;font-size:15px;font-family:DengXian;\"\u003e\u003cspan style='font-size:16px;font-family:\"Times New Roman\",serif;'\u003eCandidate Gene ID\u003c/span\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width:71.0pt;border-top:solid black 1.0pt;border-left: none;border-bottom:solid black 1.0pt;border-right:none;padding:.75pt .75pt 0in .75pt;height:35.65pt;\"\u003e\n \u003cp style=\"margin-top:0in;margin-right:0in;margin-bottom:0in;margin-left:0in;text-align:center;line-height:normal;font-size:15px;font-family:DengXian;\"\u003e\u003cspan style='font-size:16px;font-family:\"Times New Roman\",serif;'\u003eChromosome\u003c/span\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width:167.95pt;border-top:solid black 1.0pt;border-left:none;border-bottom:solid black 1.0pt;border-right:none;padding:.75pt .75pt 0in .75pt;height:35.65pt;\"\u003e\n \u003cp style=\"margin-top:0in;margin-right:0in;margin-bottom:0in;margin-left:0in;text-align:center;line-height:normal;font-size:15px;font-family:DengXian;\"\u003e\u003cspan style='font-size:16px;font-family:\"Times New Roman\",serif;'\u003eAnnotation\u003c/span\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width:82.65pt;border:none;border-bottom:solid windowtext 1.0pt;padding:.75pt .75pt 0in .75pt;height:26.35pt;\"\u003e\n \u003cp style=\"margin-top:0in;margin-right:0in;margin-bottom:0in;margin-left:0in;text-align:center;line-height:normal;font-size:15px;font-family:DengXian;\"\u003e\u003cem\u003e\u003cspan style='font-size:16px;font-family:\"Times New Roman\",serif;'\u003eqGRS4\u003c/span\u003e\u003c/em\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width:1.45in;border:none;border-bottom:solid windowtext 1.0pt;padding:.75pt .75pt 0in .75pt;height:26.35pt;\"\u003e\n \u003cp style=\"margin-top:0in;margin-right:0in;margin-bottom:0in;margin-left:0in;text-align:center;line-height:normal;font-size:15px;font-family:DengXian;\"\u003e\u003cspan style='font-size:16px;font-family:\"Times New Roman\",serif;'\u003eLOC_Os04g08740\u003c/span\u003e\u003c/p\u003e\n \u003cp style=\"margin-top:0in;margin-right:0in;margin-bottom:0in;margin-left:0in;text-align:center;line-height:normal;font-size:15px;font-family:DengXian;\"\u003e\u003cspan style='font-size:16px;font-family:\"Times New Roman\",serif;'\u003e(\u003cem\u003eETR2\u003c/em\u003e)\u003c/span\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width:71.0pt;border:none;border-bottom:solid windowtext 1.0pt;padding:.75pt .75pt 0in .75pt;height:26.35pt;\"\u003e\n \u003cp style=\"margin-top:0in;margin-right:0in;margin-bottom:0in;margin-left:0in;text-align:center;line-height:normal;font-size:15px;font-family:DengXian;\"\u003e\u003cspan style='font-size:16px;font-family:\"Times New Roman\",serif;'\u003e4\u003c/span\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width:167.95pt;border:none;border-bottom:solid windowtext 1.0pt;padding:.75pt .75pt 0in .75pt;height:26.35pt;\"\u003e\n \u003cp style=\"margin-top:0in;margin-right:0in;margin-bottom:0in;margin-left:0in;text-align:center;line-height:normal;font-size:15px;font-family:DengXian;\"\u003e\u003cspan style='font-size:16px;font-family:\"Times New Roman\",serif;'\u003eEthylene receptor\u003c/span\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width:82.65pt;border:none;padding:.75pt .75pt 0in .75pt;height:25.4pt;\"\u003e\n \u003cp style=\"margin-top:0in;margin-right:0in;margin-bottom:0in;margin-left:0in;text-align:center;line-height:normal;font-size:15px;font-family:DengXian;\"\u003e\u003cem\u003e\u003cspan style='font-size:16px;font-family:\"Times New Roman\",serif;'\u003eqGRS11\u003c/span\u003e\u003c/em\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width:1.45in;border:none;padding:.75pt .75pt 0in .75pt;height:25.4pt;\"\u003e\n \u003cp style=\"margin-top:0in;margin-right:0in;margin-bottom:0in;margin-left:0in;text-align:center;line-height:normal;font-size:15px;font-family:DengXian;\"\u003e\u003cspan style='font-size:16px;font-family:\"Times New Roman\",serif;'\u003eLOC_Os11g40090 (\u003cem\u003eRPA49\u003c/em\u003e)\u003c/span\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width:71.0pt;border:none;padding:.75pt .75pt 0in .75pt;height:25.4pt;\"\u003e\n \u003cp style=\"margin-top:0in;margin-right:0in;margin-bottom:0in;margin-left:0in;text-align:center;line-height:normal;font-size:15px;font-family:DengXian;\"\u003e\u003cspan style='font-size:16px;font-family:\"Times New Roman\",serif;'\u003e11\u003c/span\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width:167.95pt;border:none;padding:.75pt .75pt 0in .75pt;height:25.4pt;\"\u003e\n \u003cp style=\"margin-top:0in;margin-right:0in;margin-bottom:0in;margin-left:0in;text-align:center;line-height:normal;font-size:15px;font-family:DengXian;\"\u003e\u003cspan style='font-size:16px;font-family:\"Times New Roman\",serif;'\u003e\u0026nbsp;A49-like RNA polymerase I associated factor family protein\u003c/span\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width:82.65pt;padding:.75pt .75pt 0in .75pt;height:25.4pt;\"\u003e\n \u003cp style=\"margin-top:0in;margin-right:0in;margin-bottom:0in;margin-left:0in;text-align:center;line-height:normal;font-size:15px;font-family:DengXian;\"\u003e\u003cem\u003e\u003cspan style='font-size:16px;font-family:\"Times New Roman\",serif;'\u003e\u0026nbsp;\u003c/span\u003e\u003c/em\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width:1.45in;padding:.75pt .75pt 0in .75pt;height:25.4pt;\"\u003e\n \u003cp style=\"margin-top:0in;margin-right:0in;margin-bottom:0in;margin-left:0in;text-align:center;line-height:normal;font-size:15px;font-family:DengXian;\"\u003e\u003cspan style='font-size:16px;font-family:\"Times New Roman\",serif;'\u003eLOC_Os11g40100 (\u003cem\u003eOsGIF1\u003c/em\u003e)\u003c/span\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width:71.0pt;padding:.75pt .75pt 0in .75pt;height:25.4pt;\"\u003e\n \u003cp style=\"margin-top:0in;margin-right:0in;margin-bottom:0in;margin-left:0in;text-align:center;line-height:normal;font-size:15px;font-family:DengXian;\"\u003e\u003cspan style='font-size:16px;font-family:\"Times New Roman\",serif;'\u003e11\u003c/span\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width:167.95pt;padding:.75pt .75pt 0in .75pt;height:25.4pt;\"\u003e\n \u003cp style=\"margin-top:0in;margin-right:0in;margin-bottom:0in;margin-left:0in;text-align:center;line-height:normal;font-size:15px;font-family:DengXian;\"\u003e\u003cspan style='font-size:16px;font-family:\"Times New Roman\",serif;'\u003eGRF-interacting factor 2\u003c/span\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width:82.65pt;border:none;border-bottom:solid windowtext 1.0pt;padding:.75pt .75pt 0in .75pt;height:49.25pt;\"\u003e\n \u003cp style=\"margin-top:0in;margin-right:0in;margin-bottom:0in;margin-left:0in;text-align:center;line-height:normal;font-size:15px;font-family:DengXian;\"\u003e\u003cem\u003e\u003cspan style='font-size:16px;font-family:\"Times New Roman\",serif;'\u003e\u0026nbsp;\u003c/span\u003e\u003c/em\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width:1.45in;border:none;border-bottom:solid windowtext 1.0pt;padding:.75pt .75pt 0in .75pt;height:49.25pt;\"\u003e\n \u003cp style=\"margin-top:0in;margin-right:0in;margin-bottom:0in;margin-left:0in;text-align:center;line-height:normal;font-size:15px;font-family:DengXian;\"\u003e\u003cspan style='font-size:16px;font-family:\"Times New Roman\",serif;'\u003eLOC_Os11g40430\u003c/span\u003e\u003cspan style='font-size:16px;font-family:\"Times New Roman\",serif;'\u003e\u0026nbsp;(\u003c/span\u003e\u003cem\u003e\u003cspan style='font-size:16px;font-family:\"Times New Roman\",serif;'\u003eRLCK341\u003c/span\u003e\u003c/em\u003e\u003cspan style='font-size:16px;font-family:\"Times New Roman\",serif;'\u003e)\u003c/span\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width:71.0pt;border:none;border-bottom:solid windowtext 1.0pt;padding:.75pt .75pt 0in .75pt;height:49.25pt;\"\u003e\n \u003cp style=\"margin-top:0in;margin-right:0in;margin-bottom:0in;margin-left:0in;text-align:center;line-height:normal;font-size:15px;font-family:DengXian;\"\u003e\u003cspan style='font-size:16px;font-family:\"Times New Roman\",serif;'\u003e11\u003c/span\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width:167.95pt;border:none;border-bottom:solid windowtext 1.0pt;padding:.75pt .75pt 0in .75pt;height:49.25pt;\"\u003e\n \u003cp style=\"margin-top:0in;margin-right:0in;margin-bottom:0in;margin-left:0in;text-align:center;line-height:normal;font-size:15px;font-family:DengXian;\"\u003e\u003cspan style='font-size:16px;font-family:\"Times New Roman\",serif;'\u003eWall-associated receptor kinase-like 2 precursors\u003c/span\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width:82.65pt;border:none;border-bottom:solid black 1.0pt;padding:.75pt .75pt 0in .75pt;height:26.35pt;\"\u003e\n \u003cp style=\"margin-top:0in;margin-right:0in;margin-bottom:0in;margin-left:0in;text-align:center;line-height:normal;font-size:15px;font-family:DengXian;\"\u003e\u003cem\u003e\u003cspan style='font-size:16px;font-family:\"Times New Roman\",serif;'\u003eqGRS12\u003c/span\u003e\u003c/em\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width:1.45in;border:none;border-bottom:solid black 1.0pt;padding:.75pt .75pt 0in .75pt;height:26.35pt;\"\u003e\n \u003cp style=\"margin-top:0in;margin-right:0in;margin-bottom:0in;margin-left:0in;text-align:center;line-height:normal;font-size:15px;font-family:DengXian;\"\u003e\u003cspan style='font-size:16px;font-family:\"Times New Roman\",serif;'\u003eLOC_Os12g29350\u003c/span\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width:71.0pt;border:none;border-bottom:solid black 1.0pt;padding:.75pt .75pt 0in .75pt;height:26.35pt;\"\u003e\n \u003cp style=\"margin-top:0in;margin-right:0in;margin-bottom:0in;margin-left:0in;text-align:center;line-height:normal;font-size:15px;font-family:DengXian;\"\u003e\u003cspan style='font-size:16px;font-family:\"Times New Roman\",serif;'\u003e12\u003c/span\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width:167.95pt;border:none;border-bottom:solid black 1.0pt;padding:.75pt .75pt 0in .75pt;height:26.35pt;\"\u003e\n \u003cp style=\"margin-top:0in;margin-right:0in;margin-bottom:0in;margin-left:0in;text-align:center;line-height:normal;font-size:15px;font-family:DengXian;\"\u003e\u003cspan style='font-size:16px;font-family:\"Times New Roman\",serif;'\u003eATP binding protein\u003c/span\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n\u003c/table\u003e\n\u003cp\u003eBased on gravitropic response speed, the fastest and slowest 3 extreme accessions were selected respectively from the 226 accessions. The fastest 3 extreme accessions were Zaohandao(F1), C22(F2) and Xianggu(F3), and the slowest were BLCO.BRANCO(S1), IPEACO162(S2) and Gaoyangdiandao(S3). The lead SNP (1217439378) of \u003cem\u003eqGRS12\u003c/em\u003e indicated different allele types between 2 groups of accessions, that all three slowest accessions with the G allele, while all three fastest accessions with the alleles of both A and G. The expression patterns of the five genes in these 6 accessions were shown in \u003cstrong\u003eFig. 3\u003c/strong\u003e. Demonstrating that the expression level of\u0026nbsp;LOC_Os12g29350 in the three accessions with the fastest\u0026nbsp;gravitropic\u0026nbsp;response speed was much lower than that in the three accessions with the slowest\u0026nbsp;gravitropic\u0026nbsp;response speed, indicating that this gene may be involved in the negative regulation of\u0026nbsp;gravitropic\u0026nbsp;response. The expression level of \u003cem\u003eETR2\u003c/em\u003e, \u003cem\u003eRPA49\u003c/em\u003e, \u003cem\u003eOsGIF1\u0026nbsp;\u003c/em\u003eand \u003cem\u003eRLCK341\u003c/em\u003ewas low in the 6 accessions, and no significant difference was found between the two types of rice with opposite gravitropic response speed.\u003c/p\u003e"},{"header":"Discussion","content":"\u003cp\u003eThis natural mapping population has been re-sequenced and soundly assessed on root morphological characteristics and drought related traits in our previous research(Lou et al. 2015; Wu et al. 2015; Ma et al. 2016). Therefore, it is a good resource to study the relations between gravitropic response and other important agronomic traits, and to explore the genes controlling roots gravitropism.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eThe gravitropic response of radicle is primarily controlled by genetic factors but is also significantly influenced by environmental conditions(Staves et al. 1997; Norton and Price 2009).\u0026nbsp; Therefore, producing\u0026nbsp;uniform and\u0026nbsp;homogeneous growth environment is the\u0026nbsp;precondition to carry out such experiments. However, it remains challenging\u0026nbsp;to maintain an even soil environment\u0026nbsp;to observe the hidden half from the soil. Although there will be obvious differences in the root phenotype of seeds growing in the agar and soil, this agar-based screening system represents more unbiased approach to assess a biological process, and it has been extensively used to study gravitropic responses\u0026nbsp;(M\u0026uuml;ller et al. 1998; Debi et al. 2005b). Compared with the method used in other studies\u0026nbsp;(Norton and Price 2009; Uga et al. 2013), we modified the measurement protocol. Before the sowing, all the seeds were screened carefully and cold soaked to normalize their germination vigour. The bending angle was then recorded after a shorter period of 1 hour after 90\u0026deg; rotation, that is not only to save time but also to detect early variation in the trait more profoundly. Since the first 1 hour is the most efficient time in gravity-bending, after this time point the gravitropic response reduces rapidly. To gain an accurate representation of this trait, 50 seeds per accession were used in this study. After removal of non-germinating/infected seeds/\u0026nbsp;odd roots, a minimum of 20 valid samples per accession were assessed.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eRoot growth angle is an important trait that influences the ability of rice to avoid drought stress\u0026nbsp;(Uga et al. 2015a, b), because the deep roots help plants to absorb water from deep soil. The gravitropic response determines the shape of the root system, especially in the vertical dimension. As we found in this study, the gravitropic response speed significantly positively correlated with the number of deep roots and the drought resistant index. The varieties that have better gravitropic response would therefore infer better drought tolerance. This means that the gravity-bending angle could become an early indicator to predict plants\u0026rsquo; drought resistance in a cost effective high-throughput manner. Here we highlight three varieties that express the desirable gravitropism trait along with drought resistance that could be promising resources for drought resistant breeding and research (supplementary table1, bold).\u003c/p\u003e\n\u003cp\u003eNear the lead associated SNP loci, five candidate genes were selected for further study. A serine/threonine kinase, \u003cem\u003eETR2\u003c/em\u003e (LOC_Os04g08740), was found at a distance of about 40kb from the lead SNP of \u003cem\u003eqGRS4\u003c/em\u003e (4774373, Chr4), which is an ethylene receptor and acts as a negative regulator of ethylene signaling. Plants over-expressing \u003cem\u003eETR2\u003c/em\u003e display reduced ethylene sensitivity, delayed floral transition and reduced seed set\u0026nbsp;(Hada et al. 2009). A further 2 genes were found at an interval within 52 kb from \u003cem\u003eqGRS11\u003c/em\u003e (23451244, Chr11). One was related with the activity of RNA polymerase called\u0026nbsp;\u003cem\u003eRPA49\u0026nbsp;\u003c/em\u003e(LOC_Os11g40090), which interacts with \u003cem\u003eSAD1\u003c/em\u003e. A decline in the function of \u003cem\u003eSAD1\u003c/em\u003e leads to severe suppression of axillary bud outgrowth, delay in progression of developmental phases and poor root growth\u0026nbsp;(Li et al. 2015). \u0026nbsp;The other was \u003cem\u003eOsGIF1\u0026nbsp;\u003c/em\u003e(LOC_Os11g40100), which function in floral organogenesis in rice\u0026nbsp;(Liu et al. 2014). LOC_Os11g40430 (\u003cem\u003eRLCK341\u003c/em\u003e) is a cell wall-associated receptor kinase at a distance of 189kb from \u003cem\u003eqGRS11\u0026nbsp;\u003c/em\u003e(23451244, Chr11)\u0026nbsp;(Vij et al. 2008).\u0026nbsp;Gene LOC_Os12g29350, an ATP-binding protein, was located approximately 20kb away from the \u003cem\u003eqGRS12\u003c/em\u003e(17439378, Chr12) QTL. In future studies, we will\u0026nbsp;detect\u0026nbsp;their expression on the different positions of radicle to verify their function in gravity response definitively.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eThere are 11 known QTLs, that function in roots morphology and drought resistance, close to the 3 associated SNPs\u0026rsquo; physical position in the genome (\u003ca href=\"http://qtaro.abr.affrc.go.jp/\"\u003ehttp://qtaro.abr.affrc.go.jp/\u003c/a\u003e) (\u003cstrong\u003eTable 5)\u003c/strong\u003e. One of them, QTL \u003cem\u003e11-1\u003c/em\u003e controlling root thickness and number of roots past 100cm near the associated SNP on chromosome 11, was found to be co-segregated with marker \u0026nbsp;C189 (Price 2002). And C189 also co-segregated with root-penetration QTLs (Price et al. 2000) and a radicle root morphology QTL - \u003cem\u003eSRM11\u003c/em\u003e both identified by Price et al in the same mapping population (Norton and Price 2009). This interval is therefore very important in the development of the root morphology. The other 10 QTLs are all related to drought resistance, three of which are located on chromosome11, and seven QTLs were on the chromosome 12(Moncada et al. 2001; Bernier et al. 2007). This work provides further evidence to the hypothesis that gravitropic response speed is corelated with drought resistance are intrinsically related traits.\u0026nbsp;\u003c/p\u003e\n\u003cp style=\"margin-top:0in;margin-right:0in;margin-bottom:0in;margin-left:0in;text-align:justify;line-height:normal;font-size:15px;font-family:DengXian;\"\u003e\u003cstrong\u003e\u003cspan style='font-size:16px;font-family:\"Times New Roman\",serif;'\u003eTable 5. Co-localisation of QTLs for gravitropic response speed with previously identified QTLs of root and drought resistance.\u0026nbsp;\u003c/span\u003e\u003c/strong\u003e\u003cspan style='font-size:16px;font-family:\"Times New Roman\",serif;'\u003eThe information of the reported QTLs is searched from\u0026nbsp;\u003c/span\u003e\u003ca href=\"http://qtaro.abr.affrc.go.jp/\"\u003e\u003cspan style='font-size:16px;font-family:\"Times New Roman\",serif;'\u003ehttp://qtaro.abr.affrc.go.jp/\u003c/span\u003e\u003c/a\u003e\u003cu\u003e\u003cspan style='font-size:16px;font-family:\"Times New Roman\",serif;'\u003e.\u0026nbsp;\u003c/span\u003e\u003c/u\u003e\u003c/p\u003e\n\u003ctable style=\"border: none;width:100.0%;border-collapse:collapse;\"\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd style=\"width:7.94%;border-top:solid windowtext 1.0pt;border-left:none;border-bottom:solid windowtext 1.0pt;border-right:none;padding:0in 5.4pt 0in 5.4pt;height:72.6pt;\"\u003e\n \u003cp style=\"margin-top:0in;margin-right:0in;margin-bottom:0in;margin-left:0in;text-align:justify;line-height:normal;font-size:15px;font-family:DengXian;\"\u003e\u003cspan style='font-size:11px;font-family:\"Times New Roman\",serif;color:black;'\u003eQTL/Gene\u003c/span\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width:9.94%;border-top:solid windowtext 1.0pt;border-left:none;border-bottom:solid windowtext 1.0pt;border-right:none;padding:0in 5.4pt 0in 5.4pt;height:72.6pt;\"\u003e\n \u003cp style=\"margin-top:0in;margin-right:0in;margin-bottom:0in;margin-left:0in;text-align:justify;line-height:normal;font-size:15px;font-family:DengXian;\"\u003e\u003cspan style='font-size:11px;font-family:\"Times New Roman\",serif;color:black;'\u003eMajor category\u003c/span\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width:7.66%;border-top:solid windowtext 1.0pt;border-left:none;border-bottom:solid windowtext 1.0pt;border-right:none;padding:0in 5.4pt 0in 5.4pt;height:72.6pt;\"\u003e\n \u003cp style=\"margin-top:0in;margin-right:0in;margin-bottom:0in;margin-left:0in;text-align:justify;line-height:normal;font-size:15px;font-family:DengXian;\"\u003e\u003cspan style='font-size:11px;font-family:\"Times New Roman\",serif;color:black;'\u003eCharacter\u003c/span\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width:4.46%;border-top:solid windowtext 1.0pt;border-left:none;border-bottom:solid windowtext 1.0pt;border-right:none;padding:0in 5.4pt 0in 5.4pt;height:72.6pt;\"\u003e\n \u003cp style=\"margin-top:0in;margin-right:0in;margin-bottom:0in;margin-left:0in;text-align:justify;line-height:normal;font-size:15px;font-family:DengXian;\"\u003e\u003cspan style='font-size:11px;font-family:\"Times New Roman\",serif;color:black;'\u003eChr\u003c/span\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width:7.54%;border-top:solid windowtext 1.0pt;border-left:none;border-bottom:solid windowtext 1.0pt;border-right:none;padding:0in 5.4pt 0in 5.4pt;height:72.6pt;\"\u003e\n \u003cp style=\"margin-top:0in;margin-right:0in;margin-bottom:0in;margin-left:0in;text-align:justify;line-height:normal;font-size:15px;font-family:DengXian;\"\u003e\u003cspan style='font-size:11px;font-family:\"Times New Roman\",serif;color:black;'\u003eGenome Start\u003c/span\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width:7.54%;border-top:solid windowtext 1.0pt;border-left:none;border-bottom:solid windowtext 1.0pt;border-right:none;padding:0in 5.4pt 0in 5.4pt;height:72.6pt;\"\u003e\n \u003cp style=\"margin-top:0in;margin-right:0in;margin-bottom:0in;margin-left:0in;text-align:justify;line-height:normal;font-size:15px;font-family:DengXian;\"\u003e\u003cspan style='font-size:11px;font-family:\"Times New Roman\",serif;color:black;'\u003eGenome End\u003c/span\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width:24.6%;border-top:solid windowtext 1.0pt;border-left:none;border-bottom:solid windowtext 1.0pt;border-right:none;padding:0in 5.4pt 0in 5.4pt;height:72.6pt;\"\u003e\n \u003cp style=\"margin-top:0in;margin-right:0in;margin-bottom:0in;margin-left:0in;text-align:justify;line-height:normal;font-size:15px;font-family:DengXian;\"\u003e\u003cspan style='font-size:11px;font-family:\"Times New Roman\",serif;color:black;'\u003eReference\u003c/span\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width:11.02%;border-top:solid windowtext 1.0pt;border-left:none;border-bottom:solid windowtext 1.0pt;border-right:none;padding:0in 5.4pt 0in 5.4pt;height:72.6pt;\"\u003e\n \u003cp style=\"margin-top:0in;margin-right:0in;margin-bottom:0in;margin-left:0in;text-align:justify;line-height:normal;font-size:15px;font-family:DengXian;\"\u003e\u003cspan style='font-size:11px;font-family:\"Times New Roman\",serif;color:black;'\u003eCo-segregated marker\u003c/span\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width:8.28%;border-top:solid windowtext 1.0pt;border-left:none;border-bottom:solid windowtext 1.0pt;border-right:none;padding:0in 5.4pt 0in 5.4pt;height:72.6pt;\"\u003e\n \u003cp style=\"margin-top:0in;margin-right:0in;margin-bottom:0in;margin-left:0in;text-align:justify;line-height:normal;font-size:15px;font-family:DengXian;\"\u003e\u003cspan style='font-size:11px;font-family:\"Times New Roman\",serif;color:black;'\u003eGravitropic response speed QTLs\u003c/span\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width:11.02%;border-top:solid windowtext 1.0pt;border-left:none;border-bottom:solid windowtext 1.0pt;border-right:none;padding:0in 5.4pt 0in 5.4pt;height:72.6pt;\"\u003e\n \u003cp style=\"margin-top:0in;margin-right:0in;margin-bottom:0in;margin-left:0in;text-align:justify;line-height:normal;font-size:15px;font-family:DengXian;\"\u003e\u003cspan style='font-size:11px;font-family:\"Times New Roman\",serif;color:black;'\u003eAssociated SNP position\u0026nbsp;\u003c/span\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width:7.94%;padding:0in 5.4pt 0in 5.4pt;height:1.2in;\"\u003e\n \u003cp style=\"margin-top:0in;margin-right:0in;margin-bottom:0in;margin-left:0in;text-align:center;line-height:normal;font-size:15px;font-family:DengXian;\"\u003e\u003cem\u003e\u003cspan style='font-size:11px;font-family:\"Times New Roman\",serif;color:black;'\u003e11-1\u003c/span\u003e\u003c/em\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width:9.94%;padding:0in 5.4pt 0in 5.4pt;height:1.2in;\"\u003e\n \u003cp style=\"margin-top:0in;margin-right:0in;margin-bottom:0in;margin-left:0in;text-align:justify;line-height:normal;font-size:15px;font-family:DengXian;\"\u003e\u003cspan style='font-size:11px;font-family:\"Times New Roman\",serif;color:black;'\u003eMorphological trait\u003c/span\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width:7.66%;padding:0in 5.4pt 0in 5.4pt;height:1.2in;\"\u003e\n \u003cp style=\"margin-top:0in;margin-right:0in;margin-bottom:0in;margin-left:0in;text-align:justify;line-height:normal;font-size:15px;font-family:DengXian;\"\u003e\u003cspan style='font-size:11px;font-family:\"Times New Roman\",serif;color:black;'\u003eRoot thickness, number of roots past 100cm\u003c/span\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width:4.46%;padding:0in 5.4pt 0in 5.4pt;height:1.2in;\"\u003e\n \u003cp style=\"margin-top:0in;margin-right:0in;margin-bottom:0in;margin-left:0in;text-align:justify;line-height:normal;font-size:15px;font-family:DengXian;\"\u003e\u003cspan style='font-size:11px;font-family:\"Times New Roman\",serif;color:black;'\u003e11\u003c/span\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width:7.54%;padding:0in 5.4pt 0in 5.4pt;height:1.2in;\"\u003e\u003cbr\u003e\u003c/td\u003e\n \u003ctd style=\"width:7.54%;padding:0in 5.4pt 0in 5.4pt;height:1.2in;\"\u003e\u003cbr\u003e\u003c/td\u003e\n \u003ctd style=\"width:24.6%;padding:0in 5.4pt 0in 5.4pt;height:1.2in;\"\u003e\n \u003cp style=\"margin-top:0in;margin-right:0in;margin-bottom:0in;margin-left:0in;text-align:justify;line-height:normal;font-size:15px;font-family:DengXian;\"\u003e\u003cspan style='font-size:11px;font-family:\"Times New Roman\",serif;color:black;'\u003ehttps://doi.org/10.1016/S0378-4290(02)00010-2\u003c/span\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width:11.02%;padding:0in 5.4pt 0in 5.4pt;height:1.2in;\"\u003e\n \u003cp style=\"margin-top:0in;margin-right:0in;margin-bottom:0in;margin-left:0in;text-align:justify;line-height:normal;font-size:15px;font-family:DengXian;\"\u003e\u003cspan style='font-size:11px;font-family:\"Times New Roman\",serif;color:black;'\u003eC189(23732960-23734930)\u003c/span\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd rowspan=\"4\" style=\"width:8.28%;border:none;border-bottom: solid black 1.0pt;padding:0in 5.4pt 0in 5.4pt;height:1.2in;\"\u003e\n \u003cp style=\"margin-top:0in;margin-right:0in;margin-bottom:0in;margin-left:0in;text-align:center;line-height:normal;font-size:15px;font-family:DengXian;\"\u003e\u003cem\u003e\u003cspan style='font-size:11px;font-family:\"Times New Roman\",serif;color:black;'\u003eqGRS11\u003c/span\u003e\u003c/em\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd rowspan=\"4\" style=\"width:11.02%;border:none;border-bottom: solid black 1.0pt;padding:0in 5.4pt 0in 5.4pt;height:1.2in;\"\u003e\n \u003cp style=\"margin-top:0in;margin-right:0in;margin-bottom:0in;margin-left:0in;text-align:center;line-height:normal;font-size:15px;font-family:DengXian;\"\u003e\u003cspan style='font-size:11px;font-family:\"Times New Roman\",serif;color:black;'\u003eChr11-23451244\u003c/span\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width:7.94%;padding:0in 5.4pt 0in 5.4pt;height:1.2in;\"\u003e\n \u003cp style=\"margin-top:0in;margin-right:0in;margin-bottom:0in;margin-left:0in;text-align:justify;line-height:normal;font-size:15px;font-family:DengXian;\"\u003e\u003cem\u003e\u003cspan style='font-size:11px;font-family:\"Times New Roman\",serif;color:black;'\u003egpl11.1\u003c/span\u003e\u003c/em\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width:9.94%;padding:0in 5.4pt 0in 5.4pt;height:1.2in;\"\u003e\n \u003cp style=\"margin-top:0in;margin-right:0in;margin-bottom:0in;margin-left:0in;text-align:justify;line-height:normal;font-size:15px;font-family:DengXian;\"\u003e\u003cspan style='font-size:11px;font-family:\"Times New Roman\",serif;color:black;'\u003eDrought Tolerance\u003c/span\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width:7.66%;padding:0in 5.4pt 0in 5.4pt;height:1.2in;\"\u003e\n \u003cp style=\"margin-top:0in;margin-right:0in;margin-bottom:0in;margin-left:0in;text-align:justify;line-height:normal;font-size:15px;font-family:DengXian;\"\u003e\u003cspan style='font-size:11px;font-family:\"Times New Roman\",serif;color:black;'\u003eGrains per plant\u003c/span\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width:4.46%;padding:0in 5.4pt 0in 5.4pt;height:1.2in;\"\u003e\n \u003cp style=\"margin-top:0in;margin-right:0in;margin-bottom:0in;margin-left:0in;text-align:justify;line-height:normal;font-size:15px;font-family:DengXian;\"\u003e\u003cspan style='font-size:11px;font-family:\"Times New Roman\",serif;color:black;'\u003e11\u003c/span\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width:7.54%;padding:0in 5.4pt 0in 5.4pt;height:1.2in;\"\u003e\n \u003cp style=\"margin-top:0in;margin-right:0in;margin-bottom:0in;margin-left:0in;text-align:justify;line-height:normal;font-size:15px;font-family:DengXian;\"\u003e\u003cspan style='font-size:11px;font-family:\"Times New Roman\",serif;color:black;'\u003e17246592\u003c/span\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width:7.54%;padding:0in 5.4pt 0in 5.4pt;height:1.2in;\"\u003e\n \u003cp style=\"margin-top:0in;margin-right:0in;margin-bottom:0in;margin-left:0in;text-align:justify;line-height:normal;font-size:15px;font-family:DengXian;\"\u003e\u003cspan style='font-size:11px;font-family:\"Times New Roman\",serif;color:black;'\u003e23651853\u003c/span\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width:24.6%;padding:0in 5.4pt 0in 5.4pt;height:1.2in;\"\u003e\n \u003cp style=\"margin-top:0in;margin-right:0in;margin-bottom:0in;margin-left:0in;text-align:justify;line-height:normal;font-size:15px;font-family:DengXian;\"\u003e\u003cspan style='font-size:11px;font-family:\"Times New Roman\",serif;color:black;'\u003ehttp://dx.doi.org/10.1007/s001220051616\u003c/span\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 11.02%;padding: 0in 5.4pt;height: 1.2in;vertical-align: top;\"\u003e\u003cbr\u003e\u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width:7.94%;padding:0in 5.4pt 0in 5.4pt;height:1.0in;\"\u003e\n \u003cp style=\"margin-top:0in;margin-right:0in;margin-bottom:0in;margin-left:0in;text-align:justify;line-height:normal;font-size:15px;font-family:DengXian;\"\u003e\u003cem\u003e\u003cspan style='font-size:11px;font-family:\"Times New Roman\",serif;color:black;'\u003egw11.1\u003c/span\u003e\u003c/em\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width:9.94%;padding:0in 5.4pt 0in 5.4pt;height:1.0in;\"\u003e\n \u003cp style=\"margin-top:0in;margin-right:0in;margin-bottom:0in;margin-left:0in;text-align:justify;line-height:normal;font-size:15px;font-family:DengXian;\"\u003e\u003cspan style='font-size:11px;font-family:\"Times New Roman\",serif;color:black;'\u003eDrought Tolerance\u003c/span\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width:7.66%;padding:0in 5.4pt 0in 5.4pt;height:1.0in;\"\u003e\n \u003cp style=\"margin-top:0in;margin-right:0in;margin-bottom:0in;margin-left:0in;text-align:justify;line-height:normal;font-size:15px;font-family:DengXian;\"\u003e\u003cspan style='font-size:11px;font-family:\"Times New Roman\",serif;color:black;'\u003e1000-grain weight\u003c/span\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width:4.46%;padding:0in 5.4pt 0in 5.4pt;height:1.0in;\"\u003e\n \u003cp style=\"margin-top:0in;margin-right:0in;margin-bottom:0in;margin-left:0in;text-align:justify;line-height:normal;font-size:15px;font-family:DengXian;\"\u003e\u003cspan style='font-size:11px;font-family:\"Times New Roman\",serif;color:black;'\u003e11\u003c/span\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width:7.54%;padding:0in 5.4pt 0in 5.4pt;height:1.0in;\"\u003e\n \u003cp style=\"margin-top:0in;margin-right:0in;margin-bottom:0in;margin-left:0in;text-align:justify;line-height:normal;font-size:15px;font-family:DengXian;\"\u003e\u003cspan style='font-size:11px;font-family:\"Times New Roman\",serif;color:black;'\u003e17246592\u003c/span\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width:7.54%;padding:0in 5.4pt 0in 5.4pt;height:1.0in;\"\u003e\n \u003cp style=\"margin-top:0in;margin-right:0in;margin-bottom:0in;margin-left:0in;text-align:justify;line-height:normal;font-size:15px;font-family:DengXian;\"\u003e\u003cspan style='font-size:11px;font-family:\"Times New Roman\",serif;color:black;'\u003e23651853\u003c/span\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width:24.6%;padding:0in 5.4pt 0in 5.4pt;height:1.0in;\"\u003e\n \u003cp style=\"margin-top:0in;margin-right:0in;margin-bottom:0in;margin-left:0in;text-align:justify;line-height:normal;font-size:15px;font-family:DengXian;\"\u003e\u003cspan style='font-size:11px;font-family:\"Times New Roman\",serif;color:black;'\u003ehttp://dx.doi.org/10.1007/s001220051616\u003c/span\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 11.02%;padding: 0in 5.4pt;height: 1in;vertical-align: top;\"\u003e\u003cbr\u003e\u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width:7.94%;border:none;border-bottom:solid windowtext 1.0pt;padding:0in 5.4pt 0in 5.4pt;height:1.0in;\"\u003e\n \u003cp style=\"margin-top:0in;margin-right:0in;margin-bottom:0in;margin-left:0in;text-align:justify;line-height:normal;font-size:15px;font-family:DengXian;\"\u003e\u003cem\u003e\u003cspan style='font-size:11px;font-family:\"Times New Roman\",serif;color:black;'\u003egw11.1\u003c/span\u003e\u003c/em\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width:9.94%;border:none;border-bottom:solid windowtext 1.0pt;padding:0in 5.4pt 0in 5.4pt;height:1.0in;\"\u003e\n \u003cp style=\"margin-top:0in;margin-right:0in;margin-bottom:0in;margin-left:0in;text-align:justify;line-height:normal;font-size:15px;font-family:DengXian;\"\u003e\u003cspan style='font-size:11px;font-family:\"Times New Roman\",serif;color:black;'\u003eDrought Tolerance\u003c/span\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width:7.66%;border:none;border-bottom:solid windowtext 1.0pt;padding:0in 5.4pt 0in 5.4pt;height:1.0in;\"\u003e\n \u003cp style=\"margin-top:0in;margin-right:0in;margin-bottom:0in;margin-left:0in;text-align:justify;line-height:normal;font-size:15px;font-family:DengXian;\"\u003e\u003cspan style='font-size:11px;font-family:\"Times New Roman\",serif;color:black;'\u003e1000-grain weight\u003c/span\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width:4.46%;border:none;border-bottom:solid windowtext 1.0pt;padding:0in 5.4pt 0in 5.4pt;height:1.0in;\"\u003e\n \u003cp style=\"margin-top:0in;margin-right:0in;margin-bottom:0in;margin-left:0in;text-align:justify;line-height:normal;font-size:15px;font-family:DengXian;\"\u003e\u003cspan style='font-size:11px;font-family:\"Times New Roman\",serif;color:black;'\u003e11\u003c/span\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width:7.54%;border:none;border-bottom:solid windowtext 1.0pt;padding:0in 5.4pt 0in 5.4pt;height:1.0in;\"\u003e\n \u003cp style=\"margin-top:0in;margin-right:0in;margin-bottom:0in;margin-left:0in;text-align:justify;line-height:normal;font-size:15px;font-family:DengXian;\"\u003e\u003cspan style='font-size:11px;font-family:\"Times New Roman\",serif;color:black;'\u003e17246592\u003c/span\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width:7.54%;border:none;border-bottom:solid windowtext 1.0pt;padding:0in 5.4pt 0in 5.4pt;height:1.0in;\"\u003e\n \u003cp style=\"margin-top:0in;margin-right:0in;margin-bottom:0in;margin-left:0in;text-align:justify;line-height:normal;font-size:15px;font-family:DengXian;\"\u003e\u003cspan style='font-size:11px;font-family:\"Times New Roman\",serif;color:black;'\u003e23651853\u003c/span\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width:24.6%;border:none;border-bottom:solid windowtext 1.0pt;padding:0in 5.4pt 0in 5.4pt;height:1.0in;\"\u003e\n \u003cp style=\"margin-top:0in;margin-right:0in;margin-bottom:0in;margin-left:0in;text-align:justify;line-height:normal;font-size:15px;font-family:DengXian;\"\u003e\u003cspan style='font-size:11px;font-family:\"Times New Roman\",serif;color:black;'\u003ehttp://dx.doi.org/10.1007/s001220051616\u003c/span\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 11.02%;border-top: none;border-right: none;border-left: none;border-image: initial;border-bottom: 1pt solid windowtext;padding: 0in 5.4pt;height: 1in;vertical-align: top;\"\u003e\n \u003cp style=\"margin-top:0in;margin-right:0in;margin-bottom:0in;margin-left:0in;text-align:left;line-height:normal;font-size:15px;font-family:DengXian;\"\u003e\u003cspan style='font-size:11px;font-family:\"Times New Roman\",serif;color:black;'\u003e\u0026nbsp;\u003c/span\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width:7.94%;padding:0in 5.4pt 0in 5.4pt;height:1.2in;\"\u003e\n \u003cp style=\"margin-top:0in;margin-right:0in;margin-bottom:0in;margin-left:0in;text-align:justify;line-height:normal;font-size:15px;font-family:DengXian;\"\u003e\u003cem\u003e\u003cspan style='font-size:11px;font-family:\"Times New Roman\",serif;color:black;'\u003eqtl12.1\u003c/span\u003e\u003c/em\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width:9.94%;padding:0in 5.4pt 0in 5.4pt;height:1.2in;\"\u003e\n \u003cp style=\"margin-top:0in;margin-right:0in;margin-bottom:0in;margin-left:0in;text-align:justify;line-height:normal;font-size:15px;font-family:DengXian;\"\u003e\u003cspan style='font-size:11px;font-family:\"Times New Roman\",serif;color:black;'\u003eDrought tolerance\u003c/span\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width:7.66%;padding:0in 5.4pt 0in 5.4pt;height:1.2in;\"\u003e\n \u003cp style=\"margin-top:0in;margin-right:0in;margin-bottom:0in;margin-left:0in;text-align:justify;line-height:normal;font-size:15px;font-family:DengXian;\"\u003e\u003cspan style='font-size:11px;font-family:\"Times New Roman\",serif;color:black;'\u003eHarvest index\u003c/span\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width:4.46%;padding:0in 5.4pt 0in 5.4pt;height:1.2in;\"\u003e\n \u003cp style=\"margin-top:0in;margin-right:0in;margin-bottom:0in;margin-left:0in;text-align:justify;line-height:normal;font-size:15px;font-family:DengXian;\"\u003e\u003cspan style='font-size:11px;font-family:\"Times New Roman\",serif;color:black;'\u003e12\u003c/span\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width:7.54%;padding:0in 5.4pt 0in 5.4pt;height:1.2in;\"\u003e\n \u003cp style=\"margin-top:0in;margin-right:0in;margin-bottom:0in;margin-left:0in;text-align:justify;line-height:normal;font-size:15px;font-family:DengXian;\"\u003e\u003cspan style='font-size:11px;font-family:\"Times New Roman\",serif;color:black;'\u003e9895474\u003c/span\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width:7.54%;padding:0in 5.4pt 0in 5.4pt;height:1.2in;\"\u003e\n \u003cp style=\"margin-top:0in;margin-right:0in;margin-bottom:0in;margin-left:0in;text-align:justify;line-height:normal;font-size:15px;font-family:DengXian;\"\u003e\u003cspan style='font-size:11px;font-family:\"Times New Roman\",serif;color:black;'\u003e17758636\u003c/span\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width:24.6%;padding:0in 5.4pt 0in 5.4pt;height:1.2in;\"\u003e\n \u003cp style=\"margin-top:0in;margin-right:0in;margin-bottom:0in;margin-left:0in;text-align:justify;line-height:normal;font-size:15px;font-family:DengXian;\"\u003e\u003cspan style='font-size:11px;font-family:\"Times New Roman\",serif;color:black;'\u003ehttps://doi.org/10.2135/cropsci2006.07.0495\u003c/span\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width:11.02%;padding:0in 5.4pt 0in 5.4pt;height:1.2in;\"\u003e\n \u003cp style=\"margin-top:0in;margin-right:0in;margin-bottom:0in;margin-left:0in;text-align:justify;line-height:normal;font-size:15px;font-family:DengXian;\"\u003e\u003cspan style='font-size:11px;font-family:\"Times New Roman\",serif;color:black;'\u003eRM7195-RM28166\u003c/span\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd rowspan=\"7\" style=\"width:8.28%;border:none;border-bottom:solid black 1.0pt;padding:0in 5.4pt 0in 5.4pt;height:1.2in;\"\u003e\n \u003cp style=\"margin-top:0in;margin-right:0in;margin-bottom:0in;margin-left:0in;text-align:center;line-height:normal;font-size:15px;font-family:DengXian;\"\u003e\u003cem\u003e\u003cspan style='font-size:11px;font-family:\"Times New Roman\",serif;color:black;'\u003eqGRS12\u003c/span\u003e\u003c/em\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd rowspan=\"7\" style=\"width:11.02%;border:none;border-bottom:solid black 1.0pt;padding:0in 5.4pt 0in 5.4pt;height:1.2in;\"\u003e\n \u003cp style=\"margin-top:0in;margin-right:0in;margin-bottom:0in;margin-left:0in;text-align:center;line-height:normal;font-size:15px;font-family:DengXian;\"\u003e\u003cspan style='font-size:11px;font-family:\"Times New Roman\",serif;color:black;'\u003eChr12-17439378\u003c/span\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width:7.94%;padding:0in 5.4pt 0in 5.4pt;height:1.2in;\"\u003e\n \u003cp style=\"margin-top:0in;margin-right:0in;margin-bottom:0in;margin-left:0in;text-align:justify;line-height:normal;font-size:15px;font-family:DengXian;\"\u003e\u003cem\u003e\u003cspan style='font-size:11px;font-family:\"Times New Roman\",serif;color:black;'\u003eqtl12.1\u003c/span\u003e\u003c/em\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width:9.94%;padding:0in 5.4pt 0in 5.4pt;height:1.2in;\"\u003e\n \u003cp style=\"margin-top:0in;margin-right:0in;margin-bottom:0in;margin-left:0in;text-align:justify;line-height:normal;font-size:15px;font-family:DengXian;\"\u003e\u003cspan style='font-size:11px;font-family:\"Times New Roman\",serif;color:black;'\u003eDrought tolerance\u003c/span\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width:7.66%;padding:0in 5.4pt 0in 5.4pt;height:1.2in;\"\u003e\n \u003cp style=\"margin-top:0in;margin-right:0in;margin-bottom:0in;margin-left:0in;text-align:justify;line-height:normal;font-size:15px;font-family:DengXian;\"\u003e\u003cspan style='font-size:11px;font-family:\"Times New Roman\",serif;color:black;'\u003ePanicle number m-2\u003c/span\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width:4.46%;padding:0in 5.4pt 0in 5.4pt;height:1.2in;\"\u003e\n \u003cp style=\"margin-top:0in;margin-right:0in;margin-bottom:0in;margin-left:0in;text-align:justify;line-height:normal;font-size:15px;font-family:DengXian;\"\u003e\u003cspan style='font-size:11px;font-family:\"Times New Roman\",serif;color:black;'\u003e12\u003c/span\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width:7.54%;padding:0in 5.4pt 0in 5.4pt;height:1.2in;\"\u003e\n \u003cp style=\"margin-top:0in;margin-right:0in;margin-bottom:0in;margin-left:0in;text-align:justify;line-height:normal;font-size:15px;font-family:DengXian;\"\u003e\u003cspan style='font-size:11px;font-family:\"Times New Roman\",serif;color:black;'\u003e9895474\u003c/span\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width:7.54%;padding:0in 5.4pt 0in 5.4pt;height:1.2in;\"\u003e\n \u003cp style=\"margin-top:0in;margin-right:0in;margin-bottom:0in;margin-left:0in;text-align:justify;line-height:normal;font-size:15px;font-family:DengXian;\"\u003e\u003cspan style='font-size:11px;font-family:\"Times New Roman\",serif;color:black;'\u003e17758636\u003c/span\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width:24.6%;padding:0in 5.4pt 0in 5.4pt;height:1.2in;\"\u003e\n \u003cp style=\"margin-top:0in;margin-right:0in;margin-bottom:0in;margin-left:0in;text-align:justify;line-height:normal;font-size:15px;font-family:DengXian;\"\u003e\u003cspan style='font-size:11px;font-family:\"Times New Roman\",serif;color:black;'\u003ehttps://doi.org/10.2135/cropsci2006.07.0495\u003c/span\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width:11.02%;padding:0in 5.4pt 0in 5.4pt;height:1.2in;\"\u003e\n \u003cp style=\"margin-top:0in;margin-right:0in;margin-bottom:0in;margin-left:0in;text-align:justify;line-height:normal;font-size:15px;font-family:DengXian;\"\u003e\u003cspan style='font-size:11px;font-family:\"Times New Roman\",serif;color:black;'\u003eRM7195-RM28166\u003c/span\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width:7.94%;padding:0in 5.4pt 0in 5.4pt;height:1.2in;\"\u003e\n \u003cp style=\"margin-top:0in;margin-right:0in;margin-bottom:0in;margin-left:0in;text-align:justify;line-height:normal;font-size:15px;font-family:DengXian;\"\u003e\u003cem\u003e\u003cspan style='font-size:11px;font-family:\"Times New Roman\",serif;color:black;'\u003eqtl12.1\u003c/span\u003e\u003c/em\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width:9.94%;padding:0in 5.4pt 0in 5.4pt;height:1.2in;\"\u003e\n \u003cp style=\"margin-top:0in;margin-right:0in;margin-bottom:0in;margin-left:0in;text-align:justify;line-height:normal;font-size:15px;font-family:DengXian;\"\u003e\u003cspan style='font-size:11px;font-family:\"Times New Roman\",serif;color:black;'\u003eDrought tolerance\u003c/span\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width:7.66%;padding:0in 5.4pt 0in 5.4pt;height:1.2in;\"\u003e\n \u003cp style=\"margin-top:0in;margin-right:0in;margin-bottom:0in;margin-left:0in;text-align:justify;line-height:normal;font-size:15px;font-family:DengXian;\"\u003e\u003cspan style='font-size:11px;font-family:\"Times New Roman\",serif;color:black;'\u003eFlowering delay\u003c/span\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width:4.46%;padding:0in 5.4pt 0in 5.4pt;height:1.2in;\"\u003e\n \u003cp style=\"margin-top:0in;margin-right:0in;margin-bottom:0in;margin-left:0in;text-align:justify;line-height:normal;font-size:15px;font-family:DengXian;\"\u003e\u003cspan style='font-size:11px;font-family:\"Times New Roman\",serif;color:black;'\u003e12\u003c/span\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width:7.54%;padding:0in 5.4pt 0in 5.4pt;height:1.2in;\"\u003e\n \u003cp style=\"margin-top:0in;margin-right:0in;margin-bottom:0in;margin-left:0in;text-align:justify;line-height:normal;font-size:15px;font-family:DengXian;\"\u003e\u003cspan style='font-size:11px;font-family:\"Times New Roman\",serif;color:black;'\u003e9895474\u003c/span\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width:7.54%;padding:0in 5.4pt 0in 5.4pt;height:1.2in;\"\u003e\n \u003cp style=\"margin-top:0in;margin-right:0in;margin-bottom:0in;margin-left:0in;text-align:justify;line-height:normal;font-size:15px;font-family:DengXian;\"\u003e\u003cspan style='font-size:11px;font-family:\"Times New Roman\",serif;color:black;'\u003e17758636\u003c/span\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width:24.6%;padding:0in 5.4pt 0in 5.4pt;height:1.2in;\"\u003e\n \u003cp style=\"margin-top:0in;margin-right:0in;margin-bottom:0in;margin-left:0in;text-align:justify;line-height:normal;font-size:15px;font-family:DengXian;\"\u003e\u003cspan style='font-size:11px;font-family:\"Times New Roman\",serif;color:black;'\u003ehttps://doi.org/10.2135/cropsci2006.07.0495\u003c/span\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width:11.02%;padding:0in 5.4pt 0in 5.4pt;height:1.2in;\"\u003e\n \u003cp style=\"margin-top:0in;margin-right:0in;margin-bottom:0in;margin-left:0in;text-align:justify;line-height:normal;font-size:15px;font-family:DengXian;\"\u003e\u003cspan style='font-size:11px;font-family:\"Times New Roman\",serif;color:black;'\u003eRM7195-RM28166\u003c/span\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width:7.94%;padding:0in 5.4pt 0in 5.4pt;height:1.2in;\"\u003e\n \u003cp style=\"margin-top:0in;margin-right:0in;margin-bottom:0in;margin-left:0in;text-align:justify;line-height:normal;font-size:15px;font-family:DengXian;\"\u003e\u003cem\u003e\u003cspan style='font-size:11px;font-family:\"Times New Roman\",serif;color:black;'\u003eqtl12.1\u003c/span\u003e\u003c/em\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width:9.94%;padding:0in 5.4pt 0in 5.4pt;height:1.2in;\"\u003e\n \u003cp style=\"margin-top:0in;margin-right:0in;margin-bottom:0in;margin-left:0in;text-align:justify;line-height:normal;font-size:15px;font-family:DengXian;\"\u003e\u003cspan style='font-size:11px;font-family:\"Times New Roman\",serif;color:black;'\u003eDrought tolerance\u003c/span\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width:7.66%;padding:0in 5.4pt 0in 5.4pt;height:1.2in;\"\u003e\n \u003cp style=\"margin-top:0in;margin-right:0in;margin-bottom:0in;margin-left:0in;text-align:justify;line-height:normal;font-size:15px;font-family:DengXian;\"\u003e\u003cspan style='font-size:11px;font-family:\"Times New Roman\",serif;color:black;'\u003eGrain yield\u003c/span\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width:4.46%;padding:0in 5.4pt 0in 5.4pt;height:1.2in;\"\u003e\n \u003cp style=\"margin-top:0in;margin-right:0in;margin-bottom:0in;margin-left:0in;text-align:justify;line-height:normal;font-size:15px;font-family:DengXian;\"\u003e\u003cspan style='font-size:11px;font-family:\"Times New Roman\",serif;color:black;'\u003e12\u003c/span\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width:7.54%;padding:0in 5.4pt 0in 5.4pt;height:1.2in;\"\u003e\n \u003cp style=\"margin-top:0in;margin-right:0in;margin-bottom:0in;margin-left:0in;text-align:justify;line-height:normal;font-size:15px;font-family:DengXian;\"\u003e\u003cspan style='font-size:11px;font-family:\"Times New Roman\",serif;color:black;'\u003e14257182\u003c/span\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width:7.54%;padding:0in 5.4pt 0in 5.4pt;height:1.2in;\"\u003e\n \u003cp style=\"margin-top:0in;margin-right:0in;margin-bottom:0in;margin-left:0in;text-align:justify;line-height:normal;font-size:15px;font-family:DengXian;\"\u003e\u003cspan style='font-size:11px;font-family:\"Times New Roman\",serif;color:black;'\u003e17546401\u003c/span\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width:24.6%;padding:0in 5.4pt 0in 5.4pt;height:1.2in;\"\u003e\n \u003cp style=\"margin-top:0in;margin-right:0in;margin-bottom:0in;margin-left:0in;text-align:justify;line-height:normal;font-size:15px;font-family:DengXian;\"\u003e\u003cspan style='font-size:11px;font-family:\"Times New Roman\",serif;color:black;'\u003ehttps://doi.org/10.2135/cropsci2006.07.0495\u003c/span\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width:11.02%;padding:0in 5.4pt 0in 5.4pt;height:1.2in;\"\u003e\n \u003cp style=\"margin-top:0in;margin-right:0in;margin-bottom:0in;margin-left:0in;text-align:justify;line-height:normal;font-size:15px;font-family:DengXian;\"\u003e\u003cspan style='font-size:11px;font-family:\"Times New Roman\",serif;color:black;'\u003eRM28048-RM511\u003c/span\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width:7.94%;padding:0in 5.4pt 0in 5.4pt;height:1.2in;\"\u003e\n \u003cp style=\"margin-top:0in;margin-right:0in;margin-bottom:0in;margin-left:0in;text-align:justify;line-height:normal;font-size:15px;font-family:DengXian;\"\u003e\u003cem\u003e\u003cspan style='font-size:11px;font-family:\"Times New Roman\",serif;color:black;'\u003eqtl12.1\u003c/span\u003e\u003c/em\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width:9.94%;padding:0in 5.4pt 0in 5.4pt;height:1.2in;\"\u003e\n \u003cp style=\"margin-top:0in;margin-right:0in;margin-bottom:0in;margin-left:0in;text-align:justify;line-height:normal;font-size:15px;font-family:DengXian;\"\u003e\u003cspan style='font-size:11px;font-family:\"Times New Roman\",serif;color:black;'\u003eDrought tolerance\u003c/span\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width:7.66%;padding:0in 5.4pt 0in 5.4pt;height:1.2in;\"\u003e\n \u003cp style=\"margin-top:0in;margin-right:0in;margin-bottom:0in;margin-left:0in;text-align:justify;line-height:normal;font-size:15px;font-family:DengXian;\"\u003e\u003cspan style='font-size:11px;font-family:\"Times New Roman\",serif;color:black;'\u003eBiomass yield\u003c/span\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width:4.46%;padding:0in 5.4pt 0in 5.4pt;height:1.2in;\"\u003e\n \u003cp style=\"margin-top:0in;margin-right:0in;margin-bottom:0in;margin-left:0in;text-align:justify;line-height:normal;font-size:15px;font-family:DengXian;\"\u003e\u003cspan style='font-size:11px;font-family:\"Times New Roman\",serif;color:black;'\u003e12\u003c/span\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width:7.54%;padding:0in 5.4pt 0in 5.4pt;height:1.2in;\"\u003e\n \u003cp style=\"margin-top:0in;margin-right:0in;margin-bottom:0in;margin-left:0in;text-align:justify;line-height:normal;font-size:15px;font-family:DengXian;\"\u003e\u003cspan style='font-size:11px;font-family:\"Times New Roman\",serif;color:black;'\u003e14257182\u003c/span\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width:7.54%;padding:0in 5.4pt 0in 5.4pt;height:1.2in;\"\u003e\n \u003cp style=\"margin-top:0in;margin-right:0in;margin-bottom:0in;margin-left:0in;text-align:justify;line-height:normal;font-size:15px;font-family:DengXian;\"\u003e\u003cspan style='font-size:11px;font-family:\"Times New Roman\",serif;color:black;'\u003e17758636\u003c/span\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width:24.6%;padding:0in 5.4pt 0in 5.4pt;height:1.2in;\"\u003e\n \u003cp style=\"margin-top:0in;margin-right:0in;margin-bottom:0in;margin-left:0in;text-align:justify;line-height:normal;font-size:15px;font-family:DengXian;\"\u003e\u003cspan style='font-size:11px;font-family:\"Times New Roman\",serif;color:black;'\u003ehttps://doi.org/10.2135/cropsci2006.07.0495\u003c/span\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width:11.02%;padding:0in 5.4pt 0in 5.4pt;height:1.2in;\"\u003e\n \u003cp style=\"margin-top:0in;margin-right:0in;margin-bottom:0in;margin-left:0in;text-align:justify;line-height:normal;font-size:15px;font-family:DengXian;\"\u003e\u003cspan style='font-size:11px;font-family:\"Times New Roman\",serif;color:black;'\u003eRM28048-RM28166\u003c/span\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width:7.94%;padding:0in 5.4pt 0in 5.4pt;height:1.2in;\"\u003e\n \u003cp style=\"margin-top:0in;margin-right:0in;margin-bottom:0in;margin-left:0in;text-align:justify;line-height:normal;font-size:15px;font-family:DengXian;\"\u003e\u003cem\u003e\u003cspan style='font-size:11px;font-family:\"Times New Roman\",serif;color:black;'\u003eqtl12.1\u003c/span\u003e\u003c/em\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width:9.94%;padding:0in 5.4pt 0in 5.4pt;height:1.2in;\"\u003e\n \u003cp style=\"margin-top:0in;margin-right:0in;margin-bottom:0in;margin-left:0in;text-align:justify;line-height:normal;font-size:15px;font-family:DengXian;\"\u003e\u003cspan style='font-size:11px;font-family:\"Times New Roman\",serif;color:black;'\u003eDrought tolerance\u003c/span\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width:7.66%;padding:0in 5.4pt 0in 5.4pt;height:1.2in;\"\u003e\n \u003cp style=\"margin-top:0in;margin-right:0in;margin-bottom:0in;margin-left:0in;text-align:justify;line-height:normal;font-size:15px;font-family:DengXian;\"\u003e\u003cspan style='font-size:11px;font-family:\"Times New Roman\",serif;color:black;'\u003ePlant heigh at maturity\u003c/span\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width:4.46%;padding:0in 5.4pt 0in 5.4pt;height:1.2in;\"\u003e\n \u003cp style=\"margin-top:0in;margin-right:0in;margin-bottom:0in;margin-left:0in;text-align:justify;line-height:normal;font-size:15px;font-family:DengXian;\"\u003e\u003cspan style='font-size:11px;font-family:\"Times New Roman\",serif;color:black;'\u003e12\u003c/span\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width:7.54%;padding:0in 5.4pt 0in 5.4pt;height:1.2in;\"\u003e\n \u003cp style=\"margin-top:0in;margin-right:0in;margin-bottom:0in;margin-left:0in;text-align:justify;line-height:normal;font-size:15px;font-family:DengXian;\"\u003e\u003cspan style='font-size:11px;font-family:\"Times New Roman\",serif;color:black;'\u003e14257182\u003c/span\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width:7.54%;padding:0in 5.4pt 0in 5.4pt;height:1.2in;\"\u003e\n \u003cp style=\"margin-top:0in;margin-right:0in;margin-bottom:0in;margin-left:0in;text-align:justify;line-height:normal;font-size:15px;font-family:DengXian;\"\u003e\u003cspan style='font-size:11px;font-family:\"Times New Roman\",serif;color:black;'\u003e17758636\u003c/span\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width:24.6%;padding:0in 5.4pt 0in 5.4pt;height:1.2in;\"\u003e\n \u003cp style=\"margin-top:0in;margin-right:0in;margin-bottom:0in;margin-left:0in;text-align:justify;line-height:normal;font-size:15px;font-family:DengXian;\"\u003e\u003cspan style='font-size:11px;font-family:\"Times New Roman\",serif;color:black;'\u003ehttps://doi.org/10.2135/cropsci2006.07.0495\u003c/span\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width:11.02%;padding:0in 5.4pt 0in 5.4pt;height:1.2in;\"\u003e\n \u003cp style=\"margin-top:0in;margin-right:0in;margin-bottom:0in;margin-left:0in;text-align:justify;line-height:normal;font-size:15px;font-family:DengXian;\"\u003e\u003cspan style='font-size:11px;font-family:\"Times New Roman\",serif;color:black;'\u003eRM28048-RM28166\u003c/span\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width:7.94%;border:none;border-bottom:solid windowtext 1.0pt;padding:0in 5.4pt 0in 5.4pt;height:87.0pt;\"\u003e\n \u003cp style=\"margin-top:0in;margin-right:0in;margin-bottom:0in;margin-left:0in;text-align:justify;line-height:normal;font-size:15px;font-family:DengXian;\"\u003e\u003cem\u003e\u003cspan style='font-size:11px;font-family:\"Times New Roman\",serif;color:black;'\u003eqtl12.1\u003c/span\u003e\u003c/em\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width:9.94%;border:none;border-bottom:solid windowtext 1.0pt;padding:0in 5.4pt 0in 5.4pt;height:87.0pt;\"\u003e\n \u003cp style=\"margin-top:0in;margin-right:0in;margin-bottom:0in;margin-left:0in;text-align:justify;line-height:normal;font-size:15px;font-family:DengXian;\"\u003e\u003cspan style='font-size:11px;font-family:\"Times New Roman\",serif;color:black;'\u003eDrought tolerance\u003c/span\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width:7.66%;border:none;border-bottom:solid windowtext 1.0pt;padding:0in 5.4pt 0in 5.4pt;height:87.0pt;\"\u003e\n \u003cp style=\"margin-top:0in;margin-right:0in;margin-bottom:0in;margin-left:0in;text-align:justify;line-height:normal;font-size:15px;font-family:DengXian;\"\u003e\u003cspan style='font-size:11px;font-family:\"Times New Roman\",serif;color:black;'\u003eDrought response index\u003c/span\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width:4.46%;border:none;border-bottom:solid windowtext 1.0pt;padding:0in 5.4pt 0in 5.4pt;height:87.0pt;\"\u003e\n \u003cp style=\"margin-top:0in;margin-right:0in;margin-bottom:0in;margin-left:0in;text-align:justify;line-height:normal;font-size:15px;font-family:DengXian;\"\u003e\u003cspan style='font-size:11px;font-family:\"Times New Roman\",serif;color:black;'\u003e12\u003c/span\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width:7.54%;border:none;border-bottom:solid windowtext 1.0pt;padding:0in 5.4pt 0in 5.4pt;height:87.0pt;\"\u003e\n \u003cp style=\"margin-top:0in;margin-right:0in;margin-bottom:0in;margin-left:0in;text-align:justify;line-height:normal;font-size:15px;font-family:DengXian;\"\u003e\u003cspan style='font-size:11px;font-family:\"Times New Roman\",serif;color:black;'\u003e14257182\u003c/span\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width:7.54%;border:none;border-bottom:solid windowtext 1.0pt;padding:0in 5.4pt 0in 5.4pt;height:87.0pt;\"\u003e\n \u003cp style=\"margin-top:0in;margin-right:0in;margin-bottom:0in;margin-left:0in;text-align:justify;line-height:normal;font-size:15px;font-family:DengXian;\"\u003e\u003cspan style='font-size:11px;font-family:\"Times New Roman\",serif;color:black;'\u003e17546401\u003c/span\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width:24.6%;border:none;border-bottom:solid windowtext 1.0pt;padding:0in 5.4pt 0in 5.4pt;height:87.0pt;\"\u003e\n \u003cp style=\"margin-top:0in;margin-right:0in;margin-bottom:0in;margin-left:0in;text-align:justify;line-height:normal;font-size:15px;font-family:DengXian;\"\u003e\u003cspan style='font-size:11px;font-family:\"Times New Roman\",serif;color:black;'\u003ehttps://doi.org/10.2135/cropsci2006.07.0495\u003c/span\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width:11.02%;border:none;border-bottom:solid windowtext 1.0pt;padding:0in 5.4pt 0in 5.4pt;height:87.0pt;\"\u003e\n \u003cp style=\"margin-top:0in;margin-right:0in;margin-bottom:0in;margin-left:0in;text-align:justify;line-height:normal;font-size:15px;font-family:DengXian;\"\u003e\u003cspan style='font-size:11px;font-family:\"Times New Roman\",serif;color:black;'\u003eRM28048-RM511\u003c/span\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n\u003c/table\u003e"},{"header":"Conclusion","content":"\u003cp\u003eThis study modified the assessment method of radicle gravitropic response to be more efficient and precise. Using a natural population that already has plenty of root and drought resistance data, 3 significant associated QTLs were identified by GWAS. The trait of radicle gravitropic response speed found to be positively corelated with the deep roots and drought resistance. Five candidate genes have been chosen for further verification by qPCR in 6 extreme varieties, and LOC_Os12g29350 was higher expressed in the slow gravitropic response varieties. Some known QTLs of roots traits and drought resistance located nearby the associated QTLs identified in this study, which confirmed the close relationship between radicle gravitropism and the drought resistance.\u003c/p\u003e"},{"header":"Materials And Methods","content":"\u003cp\u003e\u003cstrong\u003ePlant material\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe association population used in this study is composed of 131 rice accessions from the mini-core collection of Chinese rice germplasm along with 95 rice accessions from core drought-resistance core rice germplasm collection. \u0026nbsp;Of this population, 133 accessions are \u003cem\u003eIndica\u003c/em\u003e rice and 93 accessions are \u003cem\u003eJaponica\u003c/em\u003e rice. All rice seeds were provided by Shanghai Agrobiological Gene Center and harvested in the same season.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eEvaluation of root gravitropism\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eBased on the root gravitropic curvature experiments described by Uga et al(Uga et al. 2013)\u0026nbsp;and Norton and Price et al.(Norton and Price 2009), the gravitropic response speed of radicle roots was measured with some modification. The growth direction of the root tip was first marked when the radicle root grew to 1-2 cm. The root tip was then rotated from the normal vertical axis to the horizontal axis by rotating the agarose plate by 90 degrees. Now under the effect of gravity, the growth direction of radicle root tip was observed, and its position marked again after a growth period of 1 hour. The angle between the two marked root tip growth directions was recorded as the gravitropic response speed. The ratio of radicle root length to the growth period, starting at the date of sowing, was recorded as the radicle root growth speed. The gravitropic response speed of each panel member was calculated after removing the outliers. At least 20 viable seeds for each accession were used to calculate for its average gravitropic response speed.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eThere were 7 steps to evaluation of root gravitropism, and the details were shown as \u003cstrong\u003eFig.4\u003c/strong\u003e. (1) Screening seeds. Using salt solution with the specific gravity at 1.1, the sterile and\u0026nbsp;mouldy\u0026nbsp;grains were removed, and about 50 uniform and full seeds were left for further experiment. (2) Sterilization. The seeds were sterilized with a 2.5% sodium hypochlorite solution for 15 minutes. Then, the seeds were rinsed with running water to clear the disinfectant\u0026nbsp;away. (3) Cold soaking. Put the seeds in culture dishes lined with filter paper. Added some tap-water into the dishes to just submerge the seeds. Then covered the dishes with plastic wrap and stored in a 4℃ refrigerator for 7 days to make seeds fully soaked and ready for germination. (4) Making agarose gel. The 0.8% agarose was boiled and cooled, then poured into cuboid plastic\u0026nbsp;transparent\u0026nbsp;germination board with a length of 12 cm, a width of 1.3 cm and a height of 10 cm, that have been placed in\u0026nbsp;a\u0026nbsp;container with depth more than 12 cm. The final height of the solid gel was about 9 cm. (5) Sowing. Before sowing, the seeds were placed in a 28\u0026deg;C growth chamber for about 19 h. After the agar gel was completely cooled and solidified, germination plates were token out from the container and a lid with a length of 12.3 cm, a width of 1.8 cm, and a height of 1.3 cm was added at the bottom. The seeds with the same germination status were selected and sown evenly on the agar plate with embryos downward. 7 seeds per board, and more than 5 boards per accession. The accession name and sowing time were marked on left margin of the board. (6) Rotation after first lineation. After sowing, the plates were placed in an incubator at 28\u0026deg;C without light. About 1 day later, when most of the radicle roots of the same accession grow to length at 1 to 2cm, a line tangent to the growth direction of the root\u0026nbsp;tip\u0026nbsp;was marked on the board, and the current time was recorded. Then, the plates were rotated 90\u0026deg;and put into the growth chamber at 28\u0026deg;C immediately. (7) Second lineation. After 1 hour of growth, another line tangent to the growth direction of the new root tip was marked. The root length and bending angle of the root tip was measured according the two tangent lines, and gravitropic response speed and growth speed of radicle roots were then calculated as described above.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eGenome-wide association study\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eTo perform basic statistical analysis on the phenotypic traits, we calculated the average value, standard deviation, coefficient of variation and correlation coefficient as well as to make frequency distribution graph.\u003c/p\u003e\n\u003cp\u003eThe GWAS analysis was conducted via the efficient mixed-model association (EMMA) method which is available within the Genome Association and Prediction Integrated Tool (GAPIT) R package(Lipka et al. 2012).This mapping population has been used in our previous studies for a lot of other important\u0026nbsp;agronomic traits, so its molecular data and analysis method have been ready-made already(Lou et al. 2015; Wu et al. 2015; Ma et al. 2016).\u0026nbsp;Totally, 3038555 SNPs with the minor allele frequency (MAF)\u0026nbsp;of \u0026ge;5% across the panel were used for GWAS. The model was adjusted using a kinship matrix and principal component eigenvectors to remove the confounding effects of hidden family relationships within the population and population structure. A kinship matrix was created following the Van Raden protocol within GAPIT, and the first 2 components were used in principal components (PC) adjustment. The threshold of -log\u003csub\u003e10\u003c/sub\u003e\u003csup\u003e(P)\u003c/sup\u003e=5.0 was used to declare the presence of associated QTLs (quantitative traits loci) for GWAS mapping.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eAccording to the GWAS results, the annotation information of all genes within the range of 200 kb on the two flanks of the lead associated SNP loci was analyzed and the genes whose function are known to may be relate to roots development were selected for further expression test. The linkage disequilibrium(LD) decay distance in \u003cem\u003eIndica\u003c/em\u003e and \u003cem\u003eJaponica\u003c/em\u003e extends to between ~75 and 200 kb, so the annotated genes in the range of 200 kb were considered here(Mather et al. 2007). Additionally, a further selection step was carried out using transcriptome data of rice root(Lou et al. 2017), where genes that were highly expressed in roots were preferentially selected for further analysis.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eRNA extraction and expression verification\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eTo determine if selected candidate genes were differentially expressed between lines in the population, qPCR was conducted. A total of 6 accessions were used for expression verification, using three extreme accessions with the fastest and three with the slowest gravitropic response speed that had been selected from the association population of 226 rice accessions. The radicle roots were sampled when they grew to 1-2 cm and were flash frozen in liquid nitrogen, then stored at -80\u0026nbsp;\u0026deg;C\u0026nbsp;for later use. The total RNA of 10 pooled radicle roots was extracted using the TRNzol reagent (TIANGEN), and cDNA was synthesized by EasyScript\u0026reg;One-step gDNA Removal and cDNA Synthesis SuperMix following the manufacturers protocol (TransGen Biotech).\u0026nbsp;Primer Premier v5.0 was used to design primers using\u0026nbsp;the genome sequence of Nipponbare as a sequence reference\u0026nbsp;(\u003cstrong\u003eSupplementary Table 2\u003c/strong\u003e), the target fragment lengths were expected to be between 150bp - 250bp. Real time quantitative PCR was performed in 96-well plates with an Applied Biosystems CFX96 Real-Time PCR Detection System using TransStart Top Green qPCR SuperMix (TransGen Biotech). Actin gene was used as reference gene here. All assays were carried out in triplicate or greater and the expression levels were calculated using the relative quantitation method (\u0026Delta;\u0026Delta;CT).\u003c/p\u003e"},{"header":"Abbreviations","content":"\u003cp\u003eGWAS: genome-wide association analysis; QTLs: quantitative traits; SD: standard deviation; CV: coefficient variation; PH: Plant height; TN: tiller number; DR: deep roots number; SR: shallow roots number; TR: total roots number; RDR: ratio of deep roots; R/T: roots per tiller; GSR: growth speed of radicle; DRI: drought resistant index; LD: linkage disequilibrium.\u003c/p\u003e"},{"header":"Declarations","content":"\u003cp\u003e\u003cstrong\u003eFunding\u0026nbsp;\u003c/strong\u003e\u003cstrong\u003e：\u003c/strong\u003eThis work was supported by Shanghai Agriculture Applied Technology Development Program, China (G2015060101), and the Shanghai Natural Science Foundation (19ZR1446900, 18ZR1433300).\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eConflicts of interest/Competing interests\u003c/strong\u003e ：The authors have no conflicts of interest to declare that are relevant to the content of this article\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eEthics approval\u003c/strong\u003e ：Not applicable\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eConsent to participate\u003c/strong\u003e\u003cstrong\u003e：\u003c/strong\u003eNot applicable\u0026nbsp;\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eConsent for publication\u003c/strong\u003e\u003cstrong\u003e：\u003c/strong\u003eNot applicable\u0026nbsp;\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAvailability of data and material\u003c/strong\u003e\u003cstrong\u003e：\u003c/strong\u003eThe genetic data of this population can be downloaded from http://www.ncbi.nlm.nih.gov/bioproject/PRJNA260762 and ftp://ftp-trace.ncbi.nlm.nih.gov/sra/sra-instant/reads/ByRun/sra/SRR/SRR123/SRR12 39601.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eCode availability\u003c/strong\u003e\u003cstrong\u003e：\u003c/strong\u003e Not applicable\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAuthors\u0026apos; contributions\u003c/strong\u003e ：Qiaojun Lou and Liang Chen conceptualized the study; QingSong Li carried out phenotyping studies and curated the data; FangJun Feng performed the GWAS analysis; QiaoJun Lou and YuNan Yang drafted the manuscript under the supervision of LiJun Luo; Liang Chen and Ryan Joynson reviewed and edited the final manuscript. The authors all read and approved the final manuscript.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAcknowledgements\u003c/strong\u003e\u003cstrong\u003e：\u003c/strong\u003eWe thank the Huazhong Agriculture University that provided the SNP information of Chinese core rice accessions.\u003c/p\u003e"},{"header":"References","content":"\u003cp\u003eAmzallag GN, Vaisman J (2006) Influence of brassinosteroids on initiation of the root gravitropic response in Pisum sativum seedlings. Biol Plant 50:283\u0026ndash;286. https://doi.org/10.1007/s10535-006-0021-5\u003c/p\u003e\n\u003cp\u003eBaldwin KL, Strohm AK, Masson PH (2013) Gravity sensing and signal transduction in vascular plant primary roots. Am J Bot 100:126\u0026ndash;142. https://doi.org/10.3732/ajb.1200318\u003c/p\u003e\n\u003cp\u003eBand LR, Wells DM, Larrieu A, et al (2012) Root gravitropism is regulated by a transient lateral auxin gradient controlled by a tipping-point mechanism. Proc Natl Acad Sci U S A 109:4668\u0026ndash;4673. https://doi.org/10.1073/pnas.1201498109\u003c/p\u003e\n\u003cp\u003eBennett MJ, Marchant A, Green HG, et al (1996) Arabidopsis AUX1 gene: A permease-like regulator of root gravitropism. Science (80- ) 273:948\u0026ndash;950. https://doi.org/10.1126/science.273.5277.948\u003c/p\u003e\n\u003cp\u003eBernier J, Kumar A, Ramaiah V, et al (2007) A large-effect QTL for grain yield under reproductive-stage drought stress in upland rice. Crop Sci 47:507\u0026ndash;518. https://doi.org/10.2135/cropsci2006.07.0495\u003c/p\u003e\n\u003cp\u003eBlancaflor EB, Hasenstein KH (1997) The organization of the actin cytoskeleton in vertical and graviresponding primary roots of maize. Plant Physiol 113:1447\u0026ndash;1455. https://doi.org/10.1104/pp.113.4.1447\u003c/p\u003e\n\u003cp\u003eBlancaflor EB, Masson PH (2003) Plant Gravitropism. Unraveling the Ups and Downs of a Complex Process. Plant Physiol. 133:1677\u0026ndash;1690\u003c/p\u003e\n\u003cp\u003eChang SC, Kim Y-S, Lee JY, et al (2004) Brassinolide interacts with auxin and ethylene in the root gravitropic response of maize (Zea mays). Physiol Plant 121:666\u0026ndash;673. https://doi.org/10.1111/j.0031-9317.2004.00356.x\u003c/p\u003e\n\u003cp\u003eChen R, Hilson P, Sedbrook J, et al (1998) The Arabidopsis thaliana AGRAVITROPIC 1 gene encodes a component of the polar-auxin-transport efflux carrier. Proc Natl Acad Sci U S A 95:15112\u0026ndash;15117. https://doi.org/10.1073/pnas.95.25.15112\u003c/p\u003e\n\u003cp\u003eCholodny N (1927) Wuchshormone and Tropismen bei den Pflanzen. Biol Zentralbl 47:604\u0026ndash;629\u003c/p\u003e\n\u003cp\u003eDarwin C, Darwin F (1880) The power of movement in plants. Cambridge University Press\u003c/p\u003e\n\u003cp\u003eDebi BR, Chhun T, Taketa S, et al (2005a) Defects in root development and gravity response in the aem1 mutant of rice are associated with reduced auxin efflux. 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Mol Plant 1:732\u0026ndash;750. https://doi.org/10.1093/mp/ssn047\u003c/p\u003e\n\u003cp\u003eWaidmann S, Ruiz Rosquete M, Sch\u0026ouml;ller M, et al (2019) Cytokinin functions as an asymmetric and anti-gravitropic signal in lateral roots. Nat Commun 10:1\u0026ndash;14. https://doi.org/10.1038/s41467-019-11483-4\u003c/p\u003e\n\u003cp\u003eWent F (1926) On growth-accelerating substances in the coleoptile of Avena sativa. Proc K Ned Akad van Wet 30:10\u0026ndash;19\u003c/p\u003e\n\u003cp\u003eWu J, Feng F, Lian X, et al (2015) Genome-wide Association Study (GWAS) of mesocotyl elongation based on re-sequencing approach in rice. BMC Plant Biol 15:1\u0026ndash;10. https://doi.org/10.1186/s12870-015-0608-0\u003c/p\u003e\n\u003cp\u003eYoshihara T, Spalding EP, Iino M (2013) AtLAZY1 is a signaling component required for gravitropism of the Arabidopsis thaliana inflorescence. Plant J 74:267\u0026ndash;279. https://doi.org/10.1111/tpj.12118\u003c/p\u003e\n\u003cp\u003eZhang Y, He P, Ma X, et al (2019) Auxin‐mediated statolith production for root gravitropism. New Phytol 224:761\u0026ndash;774. https://doi.org/10.1111/nph.15932\u003c/p\u003e\n\u003cp\u003eAmzallag GN, Vaisman J (2006) Influence of brassinosteroids on initiation of the root gravitropic response in Pisum sativum seedlings. Biol Plant 50:283\u0026ndash;286. https://doi.org/10.1007/s10535-006-0021-5\u003c/p\u003e\n\u003cp\u003eBaldwin KL, Strohm AK, Masson PH (2013) Gravity sensing and signal transduction in vascular plant primary roots. Am J Bot 100:126\u0026ndash;142. https://doi.org/10.3732/ajb.1200318\u003c/p\u003e\n\u003cp\u003eBand LR, Wells DM, Larrieu A, et al (2012) Root gravitropism is regulated by a transient lateral auxin gradient controlled by a tipping-point mechanism. Proc Natl Acad Sci U S A 109:4668\u0026ndash;4673. https://doi.org/10.1073/pnas.1201498109\u003c/p\u003e\n\u003cp\u003eBennett MJ, Marchant A, Green HG, et al (1996) Arabidopsis AUX1 gene: A permease-like regulator of root gravitropism. Science (80- ) 273:948\u0026ndash;950. https://doi.org/10.1126/science.273.5277.948\u003c/p\u003e\n\u003cp\u003eBernier J, Kumar A, Ramaiah V, et al (2007) A large-effect QTL for grain yield under reproductive-stage drought stress in upland rice. Crop Sci 47:507\u0026ndash;518. https://doi.org/10.2135/cropsci2006.07.0495\u003c/p\u003e\n\u003cp\u003eBlancaflor EB, Hasenstein KH (1997) The organization of the actin cytoskeleton in vertical and graviresponding primary roots of maize. Plant Physiol 113:1447\u0026ndash;1455. https://doi.org/10.1104/pp.113.4.1447\u003c/p\u003e\n\u003cp\u003eBlancaflor EB, Masson PH (2003) Plant Gravitropism. Unraveling the Ups and Downs of a Complex Process. Plant Physiol. 133:1677\u0026ndash;1690\u003c/p\u003e\n\u003cp\u003eChang SC, Kim Y-S, Lee JY, et al (2004) Brassinolide interacts with auxin and ethylene in the root gravitropic response of maize (Zea mays). Physiol Plant 121:666\u0026ndash;673. https://doi.org/10.1111/j.0031-9317.2004.00356.x\u003c/p\u003e\n\u003cp\u003eChen R, Hilson P, Sedbrook J, et al (1998) The Arabidopsis thaliana AGRAVITROPIC 1 gene encodes a component of the polar-auxin-transport efflux carrier. Proc Natl Acad Sci U S A 95:15112\u0026ndash;15117. https://doi.org/10.1073/pnas.95.25.15112\u003c/p\u003e\n\u003cp\u003eCholodny N (1927) Wuchshormone and Tropismen bei den Pflanzen. Biol Zentralbl 47:604\u0026ndash;629\u003c/p\u003e\n\u003cp\u003eDarwin C, Darwin F (1880) The power of movement in plants. Cambridge University Press\u003c/p\u003e\n\u003cp\u003eDebi BR, Chhun T, Taketa S, et al (2005a) Defects in root development and gravity response in the aem1 mutant of rice are associated with reduced auxin efflux. J Plant Physiol 162:678\u0026ndash;685. https://doi.org/10.1016/j.jplph.2004.09.012\u003c/p\u003e\n\u003cp\u003eDebi BR, Taketa S, Ichii M (2005b) Cytokinin inhibits lateral root initiation but stimulates lateral root elongation in rice (Oryza sativa). J Plant Physiol 162:507\u0026ndash;515. https://doi.org/10.1016/j.jplph.2004.08.007\u003c/p\u003e\n\u003cp\u003eDing JP, Pickard BG (1993) Mechanosensory calcium-selective cation channels in epidermal cells. Plant J 3:83\u0026ndash;110. https://doi.org/10.1046/j.1365-313x.1993.t01-4-00999.x\u003c/p\u003e\n\u003cp\u003eDong Z, Jiang C, Chen X, et al (2013) Maize LAZY1 mediates shoot gravitropism and inflorescence development through regulating auxin transport, auxin signaling, and light response. 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New Phytol 224:761\u0026ndash;774. https://doi.org/10.1111/nph.15932\u003c/p\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"hideJournal":false,"highlight":"","institution":"","isAcceptedByJournal":true,"isAuthorSuppliedPdf":false,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":true,"isPdf":false,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"researchsquare","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":true,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"/submission","title":"Research Square","twitterHandle":"researchsquare","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"","reportingPortfolio":"","inReviewEnabled":false,"inReviewRevisionsEnabled":true},"keywords":"rice, gravitropism, gravitropic response, growth angle of radicle, genome-wide association study (GWAS)","lastPublishedDoi":"10.21203/rs.3.rs-64873/v2","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-64873/v2","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003e\u003cstrong\u003eAims:\u003c/strong\u003e Gravitropism is one of the primary determinants of root development, facilitating root penetration into soil and subsequent absorption of water and nutrients. To study the gravitropism of the radicle roots, we conducted this research.\u003c/p\u003e\u003cp\u003e\u003cstrong\u003eMethods:\u003c/strong\u003e The gravitropism of 226 Chinese rice micro-core accessions and drought-resistant core accessions were assessed through the modified gravity-bending experiment and genome-wide association analysis (GWAS) was used to map the associated QTLs.\u003c/p\u003e\u003cp\u003e\u003cstrong\u003eResults:\u003c/strong\u003e The average value of gravitropic response speed of radicle roots was 41.05°/h from 16.77°/h to 62.83°/h. Significant difference (p \u0026lt; 0.002) in gravity response speed between \u003cem\u003eIndica\u003c/em\u003e (42.49°/h) and \u003cem\u003eJaponica\u003c/em\u003e (39.71°/h) subspecies was found. The gravitational response speed of radicle roots was significantly positively correlated with the number of deep roots (r =0.16), the growth speed of radicle roots (r =0.21) and the drought resistance coefficient (r=0.14).\u003c/p\u003e\u003cp\u003e\u003cstrong\u003eConclusions:\u003c/strong\u003e In total, 3 QTLs (quantitative traits) associated with gravitropic response speed were identified on chromosome 4,11 and 12. There are some known QTLs relating to roots traits and drought resistance located nearby the QTLs identified here, which confirms the close relationship between radicle gravitropism and the drought resistance. From within these intervals, 5 candidate genes were screened for qPCR in 6 extreme rice varieties, demonstrating that gene LOC_Os12g29350 may regulate gravitropism negatively and confirming its candidacy for further study. \u003c/p\u003e","manuscriptTitle":"Evaluation and GWAS of radicle gravitropic response in a core rice germplasms population","msid":"","msnumber":"","nonDraftVersions":[{"code":2,"date":"2021-03-18 19:18:56","doi":"10.21203/rs.3.rs-64873/v2","editorialEvents":[{"type":"communityComments","content":0}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"researchsquare","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":true,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"/submission","title":"Research Square","twitterHandle":"researchsquare","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"","reportingPortfolio":"","inReviewEnabled":false,"inReviewRevisionsEnabled":true}},{"code":1,"date":"2020-08-27 22:16:37","doi":"10.21203/rs.3.rs-64873/v1","editorialEvents":[{"type":"communityComments","content":0}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"researchsquare","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":true,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"/submission","title":"Research Square","twitterHandle":"researchsquare","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"","reportingPortfolio":"","inReviewEnabled":false,"inReviewRevisionsEnabled":true}}],"origin":"","ownerIdentity":"19529617-7fcc-4199-8b15-58a4d0b809f7","owner":[],"postedDate":"March 18th, 2021","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"published-in-journal","subjectAreas":[{"id":3070128,"name":"Plant Physiology and Morphology"}],"tags":[],"updatedAt":"2021-08-28T08:58:28+00:00","versionOfRecord":{"articleIdentity":"rs-64873","link":"https://doi.org/10.1007/s11104-021-05087-5","journal":{"identity":"plant-and-soil","isVorOnly":false,"title":"Plant and Soil"},"publishedOn":"2021-08-28 08:58:28","publishedOnDateReadable":"August 28th, 2021"},"versionCreatedAt":"2021-03-18 19:18:56","video":"","vorDoi":"10.1007/s11104-021-05087-5","vorDoiUrl":"https://doi.org/10.1007/s11104-021-05087-5","workflowStages":[]},"version":"v2","identity":"rs-64873","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-64873","identity":"rs-64873","version":["v2"]},"buildId":"cBFmMYwuxLRRLfASyISRj","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}