Synthesis and Germination Activity of 5-(thio)phenol-3-methylfuran-2(5H)-one Analogues as Strigolactone Mimics

Synthesis and Germination Activity of 5-(thio)phenol-3-methylfuran-2(5H)-one Analogues as Strigolactone Mimics | 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 Synthesis and Germination Activity of 5-(thio)phenol-3-methylfuran-2(5H)-one Analogues as Strigolactone Mimics Linfeng Kai, Chao Qin, Hongfei He, Qing X. Li, Rimao Hua, Pei Lv This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-6667656/v1 This work is licensed under a CC BY 4.0 License Status: Posted Version 1 posted You are reading this latest preprint version Abstract Background Phytohormones regulate plant growth, development, and stress responses. Strigolactones, a class of phytohormones, have attracted significant scientific interest due to their multifunctional roles in plant biology and ecological interactions. Results In this study,35 strigolactone mimics were efficiently synthesized via substitution reaction of pre-synthesized 5-chloro-3-methylfuran-2(5 H )-one with phenolics and benzenethiols. Most of the chemicals showed seed germination promoting activities on corn, sorghum, soybean, and sunflower seed. At a concentration of 100 mg/L, 3s and 4h showed 56% and 63% promoting rate of corn bud growth, while 50% and 62% promoting rate of sorghum root growth. The promoting rates of 3s and 4h on corn, sorghum, soybean and sunflower root growth ranged to 35–48% and 46–71%. The promotion effect of the target compound exhibited dose effect, increasing within the range of 0.01-10 mg/L and decreasing within the range of 10–100 mg/L. The optimal promotion rates for maize root and shoot growth at 3s and 4h were achieved at a concentration of 10 mg/L. 3s and 4h regulated the content of the abscisic acid, auxin, cytokinin and gibberellin content to promote plant germination. The binding energy of GR24 docking with strigolactone receptor proteins derived from Arabidopsis (AtD14) was − 7.30 kcal/mol, while 3s and 4h were − 7.96 and − 8.05 kcal/mol. Conclusions The structure-activity relationships of 35 novel strigolactone mimics and docking simulations provided structural optimization strategies for designing new strigolactone mimics as plant growth regulators. strigolactone corn germination growth hormone Figures Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Figure 6 Background Root parasitic weeds are a group of highly damaging weeds worldwide, of which Striga and Orobanche are the most widespread and damaging [ 1 ] . Striga species are severe obligatory parasites of grain and cash crops such as soybean, sorghum, corn, and rice. Once these crops are parasitized, striga can drastically reduce yields or even induce crop damage [ 2 , 3 ] . Parasitic plants of the genera Striga , Phelipanche , and Orobanche use strigolactones (SLs) in their root exudates to locate nearby hosts for growth and development [ 4 ] . Small-molecule SLs acts endogenous plant hormones [ 5 ] and have received great interest in current plant biology [ 1 – 6 ] . In the past, many studies were focused on SL biology and achieved staggering progress, permitting a highly detailed understanding of their signaling, synthesis, and biological roles [ 6 , 7 ] . Recently, Gu et al. [ 8 ] revealed a novel mechanism underlying crosstalk between SL and inorganic phosphate signaling networks in response to inorganic phosphate fluctuations. This would enable the breeding of crop plants with high phosphorus use efficiency. Ge et al. [ 9 ] reported an efficient and practical synthetic route to assemble novel highly-tens[5,5] transfused B/C strigolactam/SL analogues along with cis-fused strigolactams. It was found that SLs could regulate plant development, such as promoting the germination of root parasitic weed seeds, elongating plant primary roots, increasing root hairs, inhibiting plant branching, and inducing plant senescence [ 10 , 11 ] . Based on a structure–activity relationship of SLs, the bioactiphore in this SL family of stimulants was deduced and found to reside in the D part of the stimulant molecule. Thus, a molecular mechanism was proposed for the initial stage of seed germination [ 7 ] . Many SL derivatives have been designed and synthesized based on their molecular mechanisms, such as GR24, Nijmengen-1, and T-010 (Fig. 1 ) [ 12 – 15 ] . However, existing mimics exhibit complex structures and low stability. Therefore, there is an urgent need for simple mimics that can maintain biological functions. In this paper, we developed two series of highly efficient and structurally simple novel mimics of natural SLs and their biological activities of promoting plant germination and growth were evaluated. Their modes of action were explored by analysis plant hormone response and molecular docking. MATERIALS AND METHODS Instruments and reagents 1 H Nuclear magnetic resonance (NMR) and 13 C NMR spectra were obtained at 25°C using an Agilent DD2 AV-600 NMR spectrometer. Tetramethylsilane (TMS) was used as an internal standard. Dimethyl sulfoxide (DMSO- d 6 ) and deuterated chloroform (CDCl 3) were used as solvents. High-resolution mass spectrometry (HR-MS) data were obtained using a high-resolution Varian quantum field theory-electrospray ionization mass spectrometer (QFT-ESI). Melting points were recorded on an XT4 MP apparatus (Taike Co., Beijing, China) and uncorrected. During synthesis, all reagents and solvents (Shanghai Aladdin Biochemical Technology Co., Ltd.) were used as received. Seeds for bioactivity experiments were provided by the College of Resources and Environment of Anhui Agricultural University. During hormone measurement, high-performance liquid chromatography (HPLC) grade acetonitrile (ACN) and methanol (MeOH) were purchased from Merck (Darmstadt, Germany). MilliQ water (Millipore, Bradford, USA) was used in all experiments. All standards were purchased from Olchemim Ltd. (Olomouc, Czech Republic) and isoReag (Shanghai, China). Acetic acid and formic acid were purchased from Sigma-Aldrich (St Louis, MO, USA). Stock solutions of the standards were prepared at a concentration of 1 mg/mL in MeOH. All stock solutions were stored at -20°C. The stock solutions were diluted with MeOH to working solutions before analysis. Synthesis of target compounds Synthesis of 5-hydroxy-3-methylfuran-2 (5 H )-one (1) . A total of 10 drops of sulfuric Acid (H 2 SO 4) were added to a solution of methylmalonic acid (7.00 g, 59.3 mmol) and glyoxal (3.4 g, 59.3 mmol) in H 2 O (60 mL). The mixture was stirred at 110°C for 12 h. Then, sodium chloride (NaCl) was added to the mixture to saturation at room temperature and extracted three times with ethyl acetate (EtOAc). The combined organic layers were dried over Sodium Sulfate (Na 2 SO 4 ), filtered, and concentrated. The residue was purified by silica gel column chromatography to afford 5-hydroxy-3-methylfuran-2(5 H )-one as a solid (3.15 g, 46%). Synthesis of 5-chloro-3-methylfuran-2(5 H )-one (2) . Thionyl chloride (SOCl 2 ) (1.2 mL, 16.5 mmol) and N, N-dimethylformamide (DMF) (160 µL, 2.07 mmol) were charged in a flask. A solution of 5-hydroxy-3-methylfuran-2(5 H )-one (3.15 g, 27.64 mmol) in a minimum amount of dichloromethane (CH 2 Cl 2 ) (4 mL) was added to the above mixture. The mixture was stirred at 90°C for 10 min and cooled to room temperature. Then, the mixture was diluted with CH 2 Cl 2 -hexane (1:1) and quenched with sat. aq. sodium bicarbonate (NaHCO 3 ) at 0°C. The mixture was extracted three times with CH 2 Cl 2 -hexane (1:4). The combined organic layers were washed with brine, dried over Na 2 SO 4 , filtered, and concentrated. The residue was purified by silica gel column chromatography (10–20% EtOAc/hexane) to afford 5-chloro-3-methylfuran-2( 5H )-one as a yellowish oil (1.76 g, 47%). General procedure to prepare novel strigolactone mimics (3a-3y) . Phenols (1.89 mmol), 4A molecular sieve (1 g), potassium iodide (31 mg, 0.189 mmol), and tetrahydrofuran (20 mL) were stirred under a nitrogen atmosphere. Potassium tert-butoxide (2 mL of a 1.0 M solution in tert-butanol, 2 mmol) was introduced with cooling (ice bath) and the mixture was stirred for 10 min. Then, fresh compound 2 (250 mg, 1.89 mmol) was added and the reaction mixture was stirred for 3 h. Next, water (10 mL) was added. The product was extracted three times with EtOAc (25 mL) and dried over anhydrous Magnesium Sulfate (MgSO 4 ). The residue was purified by silica gel column chromatography to afford 3a - 3y . The physical data for 3a - 3y are provided in the Supporting Information. General procedure to prepare novel strigolactone mimics ( 4a-4i ). Thiophenols (1.89 mmol), 4A molecular sieve (1 g), and potassium iodide (31 mg, 0.189 mmol) were added to a dry round-bottomed flask containing tetrahydrofuran (20 mL) under N 2 . Potassium tert-butoxide (2 mL of a 1.0 M solution in tert-butanol, 2 mmol) was introduced with cooling (ice bath) and the mixture was stirred for 10 min. Then, fresh compound 2 (250 mg, 1.89 mmol) was added, and the reaction mixture was stirred for 3 h. Next, water (10 mL) was added. The product was extracted three times with EtOAc (25 mL) and dried over anhydrous Mg 2 SO 4 . The residue was purified by silica gel column chromatography to afford 4a - 4i . The physical data for 4a - 4i are provided in the Supporting Information. Biological assay According to the methodology described by Theologidou et al. , [ 16 ] we employed the Petri dish method for the preliminary screening of the germination activity of target compounds. Based on the preliminary screening results, we selected two of the most effective compounds ( 3s and 4h ) and measured their growth promotion rates on corn root/bud length at a concentration gradient of 0.01mg/L to 100mg/L to determine their dose effect. Subsequently, pot experiments were conducted to systematically assess the impact of compounds 3s and 4h at concentrations of 10 mg/L and 100 mg/L on key agronomic traits of corn, including plant height, aboveground biomass, and belowground biomass. Thereby, this can provide a comprehensive evaluation of their growth-promoting efficacy. The specific operational steps for the biological assay are provided in the Supporting Information. Mechanism of action of target compounds Determination of growth hormone content Corn seeds were grown for three days by the petri dish bioassay method and used as the test material. 3s and 4h were used as test agents. Pure water was used as a blank control (CK). The mechanism of the target compound in promoting plant growth and development was further investigated. Sample preparation and extraction Corn seeds with similar growth conditions were selected and soaked in 1% sodium hypochlorite and 75% ethanol for 2 min for surface disinfection. The seeds were rinsed thoroughly with disinfected deionized water and then dried naturally. Two layers of 9 cm glass fiber filter paper were placed at the bottom of a culture dish moistened with sterile water. Corn seeds were evenly sprinkled on the glass fiber filter paper. Next, 1mL of the prepared 10 mg/L 3s and 4h was sprayed into the culture dish. Usually, each culture dish contained 10 seeds. The culture dish was placed in a constant temperature incubator to allow the seeds to grow at 24°C for 3 days with a photoperiod of 12 h in order to obtain fresh solid corn samples. Fresh corn samples after 3s and 4h treatments were harvested, immediately frozen in liquid nitrogen, ground into powder (30 Hz, 1 min), and stored at -80°C until needed. 50 mg of plant sample was weighed into a 2 mL plastic microtube, frozen in liquid nitrogen, and dissolved in 1 mL methanol/water/formic acid (15:4:1, V/V/V). 10 µL of an internal standard mixed solution (100 ng/mL) was added into the extract as an internal standard (IS) for quantitative analysis. The mixture was vortexed for 10 min and then centrifuged for 5 min (12000 r/min, and 4°C). The supernatant was transferred to clean plastic microtubes, evaporated to dryness, dissolved in 100 µL of 80% methanol (V/V), and filtered through a 0.22 µm membrane filter for further Liquid Chromatography-Tandem Mass Spectrometry (LC-MS/MS) analysis [ 17 , 18 ] . UPLC conditions Sample extracts were analyzed using an UPLC-ESI-MS/MS system (UPLC, ExionLC™ AD, https://sciex.com.cn/ ; MS, QTRAP® 6500+, https://sciex.com.cn/ ). The analytical conditions were as follows: LC, Waters ACQUITY UPLC HSS T3 C18 columns (100 mm×2.1 mm i.d, 1.8 µm); solvent systems, water with 0.04% acetic acid (A) and acetonitrile with 0.04% acetic acid (B); gradient program, starting at 5% B (0–1 min), increasing to 95% B (1–8 min), 95% B (8–9 min) and finally ramping back to 5% B (9.1–12 min); flow rate, 0.35 mL/min; temperature, 40°C; injection volume, 2 µL [ 19 – 21 ] . ESI-MS/MS conditions Linear ion trap (LIT) and triple quadrupole (QQQ) scans were acquired on a triple quadrupole-linear ion trap mass spectrometer (QTRAP) (QTRAP ® 6500 + LC-MS/MS System). This system was equipped with an ESI Turbo Ion-Spray interface, operated in both positive and negative ion mode, and was controlled by Analyst 1.6.3 software (Sciex). The ESI source operation parameters were as follows: ion source, ESI+/-; source temperature, 550 ℃; ion spray voltage (IS), 5500 V (Positive)and − 4500 V (Negative); curtain gas (CUR), 35 psi. Phytohormones were analyzed using scheduled multiple reaction monitoring (MRM). Data acquisitions were performed using Analyst 1.6.3 software (Sciex). All metabolites were quantified using Multiquant 3.0.3 software (Sciex). Mass spectrometer parameters, including declustering potential (DP) and collision energies (CE) of individual MRM transitions, were further optimized. A specific set of MRM transitions was monitored for each period according to the metabolites eluted within this period [ 22 – 24 ] . Molecular docking The structures of SL receptor proteins derived from Arabidopsis (AtD14), petunia (DAD2), rice (OsD14), and solanum (ShHTLs) species have been resolved [ 25 – 28 ] . Structurally, their overall structures have a high degree of similarity in different species of plants [ 29 ] .Therefore, AtD14 (PDB: 4IH4) was selected as the receptor protein for docking experiments. AutoDock was used to perform molecular docking between the target compounds and the SL receptor protein DWARF14 (AtD14) in order to explore the mechanism of action of the target compounds. GR24 was selected as the positive control, and the compounds 3s and 4h with the best activity assay were selected as small-molecule ligands [ 30 – 32 ] . All twist angles in small molecules were released for flexible docking. Water molecules were removed from AtD14 using the AutoDock Tool, and the hydrogen module was added. On this basis, the charge distribution of small-molecule ligands was assigned [ 33 , 34 ] . In the binding mode with AtD14, the binding sites of ligands on AtD14 are mainly located near amino acid residues in proteins, such as Ser97, His247, and Asp218. Therefore, the docking box was set to encapsulate all abovementioned active sites. The empirical free energy function and Lamarckian genetic algorithm (LGA) were used for docking, with the following settings: a maximum number of energy evaluations of 30,000,000, an initial population of 150 randomly placed individuals, a maximum number of generations of 27,000, a mutation rate of 0.02, a crossover rate of 0.80 and an automatic survival (maximum number of top individuals) of 1.A total of 50 docking attempts were made for each ligand. Results And Discussion Synthesis of strigolactone mimics The synthesis of SL mimics began with 2-methylpropanedioic acid (Fig. 2 ). The intermediate 5-hydroxy-3-methylfuran-2( 5H )-one was obtained via the cyclization of methylpropanedioic acid with glyoxal. The target phenolic derivatives ( 3a - 3y ) and thiophenolic derivatives ( 4a - 4i ) were successfully obtained via chlorination of hydroxy groups followed by nucleophilic substitution. Biological assays Table 1 Promotion germination activity of 3a - 3y , 4a - 4i on corn and sorghum seed germination at 100 mg/L Growth promotion rate † (%) ± SD Cmpd Corn Sorghum Cmpd Corn Sorghum root bud root bud root bud root bud 3a 7 ± 1 12 ± 1 24 ± 1 21 ± 1 3r 34 ± 2 50 ± 2 32 ± 2 48 ± 3 3b 27 ± 3 30 ± 2 32 ± 2 38 ± 1 3s 35 ± 1 56 ± 3 40 ± 2 50 ± 2 3c 12 ± 1 19 ± 1 20 ± 1 35 ± 2 3t -9 ± 1 -6 ± 1 25 ± 1 40 ± 2 3d 21 ± 1 26 ± 1 18 ± 1 30 ± 2 3u -4 ± 1 -3 ± 1 23 ± 1 36 ± 1 3e -6 ± 1 17 ± 1 11 ± 1 19 ± 1 3v -3 ± 1 -1 ± 1 28 ± 1 34 ± 1 3f -1 ± 1 -4 ± 1 1 ± 1 15 ± 1 3w -2 ± 1 -5 ± 1 18 ± 1 26 ± 1 3g 14 ± 1 7 ± 1 20 ± 1 30 ± 2 3x -1 ± 1 -4 ± 1 25 ± 1 3 ± 1 3h -8 ± 1 -12 ± 1 21 ± 1 27 ± 1 3y -15 ± 1 -7 ± 1 26 ± 2 43 ± 2 3i 18 ± 2 16 ± 1 12 ± 1 8 ± 1 4a 7 ± 1 -6 ± 1 29 ± 2 37 ± 2 3j 2 ± 1 3 ± 1 19 ± 1 23 ± 2 4b -1 ± 1 -7 ± 1 1 ± 1 30 ± 1 3k 29 ± 2 32 ± 2 16 ± 2 30 ± 2 4c -12 ± 2 -24 ± 2 -8 ± 1 6 ± 1 3l 9 ± 1 26 ± 2 8 ± 1 26 ± 1 4d 12 ± 1 14 ± 1 15 ± 1 -5 ± 1 3m 8 ± 1 24 ± 1 33 ± 2 36 ± 2 4e 24 ± 1 26 ± 1 -4 ± 1 -9 ± 1 3n 5 ± 1 11 ± 1 18 ± 1 12 ± 1 4f -1 ± 1 -9 ± 1 5 ± 1 -2 ± 1 3o 18 ± 1 24 ± 2 30 ± 2 45 ± 3 4g 26 ± 2 42 ± 1 6 ± 1 16 ± 1 3p -3 ± 1 18 ± 1 17 ± 1 37 ± 2 4h 46 ± 2 63 ± 3 51 ± 3 62 ± 1 3q 13 ± 1 22 ± 1 29 ± 2 46 ± 2 4i 23 ± 1 40 ± 1 24 ± 1 31 ± 1 GR24 25 ± 2 30 ± 1 29 ± 1 35 ± 2 GR24 25 ± 2 30 ± 1 29 ± 1 35 ± 2 † Root/Bud growth promotion rate of Corn and Sorghum plants via the Petri dish method. Table 2 Promotion germination activity of 3a - 3y , 4a - 4i on soybean and sunflower seed germination at 100 mg/L Growth promotion rate † (%) ± SD Compd. soybean sunflower Compd. soybean Sunflower root root root root 3a -7 ± 1 12 ± 1 3r 46 ± 2 32 ± 2 3b -15 ± 3 24 ± 2 3s 47 ± 3 48 ± 2 3c 25 ± 1 39 ± 3 3t 23 ± 1 -20 ± 1 3d 27 ± 1 33 ± 1 3u 34 ± 2 7 ± 1 3e 15 ± 1 -6 ± 1 3v 24 ± 1 22 ± 1 3f 26 ± 1 12 ± 1 3w 25 ± 1 26 ± 1 3g 33 ± 2 21 ± 1 3x 24 ± 1 28 ± 1 3h 27 ± 1 3 ± 1 3y 29 ± 1 17 ± 2 3i 4 ± 1 17 ± 1 4a 15 ± 1 33 ± 2 3j 28 ± 1 1 ± 1 4b 10 ± 1 15 ± 1 3k -15 ± 2 -16 ± 2 4c 34 ± 2 14 ± 1 3l 33 ± 1 -19 ± 1 4d 22 ± 1 5 ± 1 3m 43 ± 1 6 ± 2 4e -6 ± 1 49 ± 3 3n 14 ± 1 9 ± 1 4f 30 ± 1 -1 ± 1 3o 31 ± 1 23 ± 2 4g 36 ± 2 11 ± 1 3p 32 ± 1 17 ± 1 4h 71 ± 2 68 ± 3 3q 26 ± 1 -10 ± 2 4i 25 ± 1 24 ± 1 GR24 32 ± 2 28 ± 1 GR24 32 ± 2 28 ± 1 † Root growth promotion rate of soybean and sunflower plants via the Petri dish method. The length-promoting potential of compounds 3a - 3y and 4a - 4i was preliminarily evaluated through a root/bud growth rate assay at 100 mg/L. This screening specifically targeted both dicotyledonous and monocotyledonous plant species that express SL receptor proteins, aiming to identify candidate compounds capable of activating SL-mediated growth regulatory pathways. (Tables 1 and 2 ). At 100 mg/L, most target compounds exhibited significantly promoting effects on corn and sorghum roots (5%-46%, 1%-51%) and bud (3%-63%, 6%-62%) growth. For dicotyledonous plants, most target compounds showed promoting effects on soybean root (4%-71%) and sunflower root (3%-68%). We found that when the SL mimics were 4-substituted phenoxyfuranone derivatives, they significantly promoted plant growth, and the property of the activity depended on substituent groups on the phenoxy group. The promotion activity was greater when the substituent was a halogenated element, such as bromine (3b ), chlorine ( 3c ), or fluorine ( 3f ), and higher when the substituents were electron-donating groups, such as methyl ( 3q ), ethyl ( 3r ) than that of electron-withdrawing groups, such as nitro ( 3h ). The promotion activities are not obviously changes when benzene ring was replaced by biphenyl ( 3m ), naphthalene ( 3o ), pyridine ( 3p ), isoquinoline ( 3t) . Finally, based on the principle of bioisosterism, we found that replacing phenoxy groups with phenthio groups of SL mimics increased the activity of most compounds to varying degrees. Studying the conformational relationship of the compounds synthesized in this paper may facilitate the future design of SL mimics. Next, in order to screen for the optimal concentration of compounds that promote corn germination, 3s and 4h were selected in the preliminary bioactivity assay (Fig. 3 ). We found that the greatest promotion rate on corn root and bud growth was achieved at a concentration of 10 mg/L, the promoting effect decreased as the concentrations increased and decreased. Then, in order to investigate the promoting effect of the target compounds on the entire plant, we further determined the effects of 3s and 4h on corn at concentrations of 10 and 100 mg/L using GR24 as a positive control in pot experiments (Fig. 4 ). 3s and 4h had significant effects on aboveground biomass, belowground biomass, and plant height of corn. Particularly, the effects on aboveground biomass were significantly higher than those on belowground biomass. This finding is consistent with previous petri dish experiments. 4h was the most effective at 10 mg/L, more than doubling the effect on aboveground biomass. Mechanism of promotion effect on germination We investigated the hormone levels in corn seeds treated with 3s and 4h at 10 mg/L during germination and conducted molecular docking between the compounds and AtD14 in order to preliminarily explore the mechanism of action. The abscisic acid content decreased by 9.3% and 13.7% in corn treated with 3s and 4s , respectively. The ABA glucosyl ester content in corn significantly increased (Fig. 5 A). 3-Indole acetonitrile was not found in the control (CK). In contrast, the level of 3-Indole acetonitrile was 0.28 and 0.30 ng/g after 3s and 4h treatment. The content of 3-Indole amide increased by 8 times and 21 times under 3s and 4h , respectively (Fig. 5 B). The content of L-tryptophan and indole under 3s increased by 6.5% and 12.1%, respectively. The content of L-tryptophan and Indole under 4h increased by 14.9% and 20.0%, respectively (Fig. 5 C). The cytokinin content also increased under 3s and 4h treatment. N6-Isopentenyl-adenine-7-glucoside, trans-Zeatin-O-glucoside, and trans-Zeatin-9-glucoside increased by 41.1%, 13.5%, and 12.2% under 3s and by 31.5%, 32.5%, and 15.8% under 4h , respectively (Fig. 5 D). Gibberellin A53 increased by 40.6% under 3s and 50.3% under 4h (Fig. 5 A). Table 3 Molecular docking of AtD14 protein with GR24, 3s and 4h Ligands Binding energy (kcal/mol) Hydrophobic interactions Hydrogen bond π-cation Salt bridge 3s -7.96 Phe28, Phe126, Phe159, Phe175 Phe195, Val98, Val194, Ala163, Leu248 Ser97 Phe28, His247 His96, His247 4h -8.05 Phe126, Phe159, Phe175, Phe195, Ala163, Val219, Leu248 Ser97 Phe28, His247 His96, His247 GR24 -7.30 Phe28, Phe126, Phe136, Phe159, Phe195, Val98, Val144, Val194 \ His247 His247 The docking results are presented in Fig. 6 and Table 3 . The binding energy of GR24 docking with AtD14 was − 7.3 kcal/mol. The amino acid residue (Phe28, Phe126, Phe136, Phe159, Phe195, Val98, Val144, and Val194) participated in hydrophobic interactions with GR24. His247 formed a π - cation interaction with GR24 while also forming a salt bridge. However, GR24 did not form hydrogen bonds with AtD14 (Fig. 6 A). The binding modes of compounds 3s and 4h within the active cavity are similar to that of GR24. However, the docking energies of 3s and 4h are significantly lower compared to GR24 (Table 3 ). In addition to forming hydrophobic interactions with the same residues, 3s forms hydrophobic interactions with Val98, Val194, Ala163, and Leu248 residues, while 4h binds to a different set of residues (Phe175, Ala163, Val219, and Leu248). 3s and 4h formed hydrogen bonds with Ser97, established two π-cation interactions with Phe28 and His247, and generated salt bridges with His96 and His247 in the AtD14 binding pocket. Based on the above results, we found that compared with GR24, although there was no significant difference in the number of hydrophobic interactions between 3s and 4h , they all formed hydrogen bonds with Ser97, formed more π - cation interactions with Phe28 and His247, and established more salt bridges with His96 and His247. This explained why 3s and 4h bound to AtD14 at lower binding energy and exhibited better biological assay. Plants continuously adjust their ABA content in response to physiological and environmental changes. ABA-glucosyl ester is the primary product resulting from ABA inactivation through binding with glucose and exhibits considerable stability. As the ABA content in plants decreases, ABA glucosyl ester gradually accumulates within plants, thereby facilitating plant growth and development [ 35 ] . Therefore, we hypothesize that the mechanism of action of estrogen mimetics involves binding reactions with Phe, His, and Ser residues in estrogen receptor proteins, then promoting the inactivation of abscisic acid and glucose binding in plants to accumulate ABA glucose esters, enhancing the synthesis of auxin, cytokinin, and gibberellin in plants, and ultimately regulating plant growth and development [ 36 – 39 ] . Conclusions In this study, strigolactone mimics were efficiently synthesized in three steps from methylmalonic acid, glyoxal and phenols/phenylthiophenols. The synthesized SL mimics showed significant growth-promoting activity for plants containing SL receptor proteins. In the subsequent phytohormone response analysis, the target compounds reduce the ABA content in plants by regulating the binding of ABA and glucose, and a large amount of ABA glucosyl ester accumulates. Then, the synthesis of auxin, cytokinin, and gibberellin is promoted to regulate plant growth and development. The ligand docking study showed that SL mimics may generate subsequent plant hormone responses by binding to amino acids (such as Phe, Val, Ser, and His) in SL receptor proteins within plants. This study provides significance for designing new strigolactone mimics as plant growth regulators. Abbreviations SLs Strigolactones ABA Abscisic acid CTK Cytokinin GA Gibberellin NMR Nuclear magnetic resonance TMS Tetramethylsilane DMSO-d6 Dimethyl sulfoxide CDCl3 Deuterated chloroform HR-MS High-resolution mass spectrometry HPLC High-performance liquid chromatography ACN Acetonitrile MeOH Methanol H2SO4 Sulfuric acid NaCl Sodium chloride EtOAc Ethyl acetate Na 2 SO 4 Sodium sulfate SOCl 2 Thionyl chloride DMF N, N-dimethylformamide CH 2 Cl 2 Dichloromethane NaHCO 3 Sodium bicarbonate MgSO 4 Magnesium sulfate LC-MS/MS Liquid chromatography-tandem mass spectrometry LIT Linear ion trap QQQ Triple quadrupole QTRAP Triple quadrupole-linear ion trap mass spectrometer CUR Curtain gas MRM Multiple reaction monitoring DP Declustering potential CE Collision energies Ser Serine His Histidine Asp Aspartic acid LGA Lamarckian genetic algorithm Phe Phenylalanine Val Valine Ala Alanine Leu Leucine Declarations SUPPORTING INFORMATION 1 H NMR, 13 C NMR, and HRMS spectra for the target compounds, Promotion germination activity、Corn Dose effect、Corn Plant growth promotion rate. Ethical approval and consent to participate Not applicable Consent for publication Not applicable Availability of data and materials The data sets used and/or analyzed during the current study are available from the corresponding author on reasonable request. Competing interests The authors declare no competing financial interest. Funding The authors acknowledge National Natural Science Foundation of China (31901906), Natural Science Research Project of Anhui Educational Committee (2023AH040141), Anhui Provincial Natural Science Foundation (2308085MC93), and the USDA Hatch grant (HAW05020H). Authors’ contributions Linfeng Kai: Investigation, data analysis, Writing–review & editing Writing – original draft. Chao Qin: Investigation, data analysis. Hongfei He: Validation, data analysis. Qing X Li: Writing – review & editing and data interpretation. Rimao Hua: Project administration, Supervision. Pei Lv: Writing – review & editing. Project administration, Methodology, Validation, Supervision, Resources.All authors read and approved of the final manuscript. Acknowledgments Not applicable References Kgosi R L, Zwanenbugr B, Mwakaboko A S, et al. Strigolactone analogues induce suicidal seed germination of Striga spp. in soil. Weed Res. 2012; 52(3): 197–203. Mohamed, K, I, et al. The genus Striga (Scrophulariaceae) in Afric. Ann Mo Bot Gard. 2001; 88(1): 60–103. Westwood J H, Yoder J I, Timko M P, et al. The evolution of parasitism in plants. Trends Plant Sci. 2010; 15(4): 227–35. FujiokaH, Samejma H, Mizutani M, et al. How does Striga hermonthica Bewitch its hosts? Plant Signal Behav. 2019; 14(7). Cook C E, Whichard L P, Turner B, et al. Germination of Witchweed (Striga lutea Lour.): Isolation and Properties of a Potent Stimulant. Science. 1966; 154(3753): 1189–90. Scholes J D, Press M C. Striga infestation of cereal crops – an unsolved problem in resource limited agriculture. 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Improved synthesis of strigol analog GR24 and evaluation of the biological activity of its diastereomers. J. Agric. Food Chem. 1992; 40(7): 1230–5. Gobena D, Shimels M, Rich P J, et al. Mutation in sorghum LOW GERMINATION STIMULANT 1 alters strigolactones and causes Striga resistance. Proc Natl Acad Sci.2017; 114(17): 4471–6. Johnson A W, Rosebery G, Parker C. A novel approach to Striga and Orobanche control using synthetic germination stimulants. Weed Res. 1976; 16(4): 223–7. Dvorakova M, Soudek P, Vanek T. Triazolide Strigolactone Mimics Influence Root Development in Arabidopsis. J Nat Prod. 2017; 80(5): 1318–27. Thrologidou G S, Tsialtas J T, Kaloumenos N, et al. From Petri dish to field: testing Greek lentil accessions for imazamox tolerance. Int J Plant Prod. 2016; 10(3): 265–74. Liy, Zhou C, Yan X, et al. Simultaneous analysis of ten phytohormones in Sargassum horneri by high-performance liquid chromatography with electrospray ionization tandem mass spectrometry. J Sep Sci. 2016; 39(10): 1804–13. Flokova K, Tarkowaka D, Miersch O, et al. UHPLC-MS/MS based target profiling of stress-induced phytohormones. Phytochemistry. 2014; 105: 147–57. Cai B D, Zeu J X, Gao Q, et al. Rapid and high-throughput determination of endogenous cytokinins in Oryza sativa by bare Fe3O4 nanoparticles-based magnetic solid-phase extraction. J Chromatogr A. 2014; 1340: 146–50. Niu Q, Zong Y, Qian M, et al. Simultaneous quantitative determination of major plant hormones in pear flowers and fruit by UPLC/ESI-MS/MS. Anal Methods. 2014; 6(6): 1766–73. Xiao H M, Cai W J, YE T T, et al. Spatio-temporal profiling of abscisic acid, indoleacetic acid and jasmonic acid in single rice seed during seed germination. Anal Chim Acta. 2018; 1031(1): 119–27. Pan X, Welti R, Wang X. Quantitative analysis of major plant hormones in crude plant extracts by high-performance liquid chromatography-mass spectrometry. Nat Protoc. 2010; 5(6): 986–92. Simura J, AntoniadI I, Siroka J, et al. Plant Hormonomics: Multiple Phytohormone Profiling by Targeted Metabolomics. Plant Physiol. 2018. 177(2); 476–89. Cui K, Lin Y, Zhou X, et al. Comparison of sample pretreatment methods for the determination of multiple phytohormones in plant samples by liquid chromatography–electrospray ionization-tandem mass spectrometry. Microchem J. 2015; 121: 25–31. Zhang Y Y, Wang D W, Shen Y Q, et al. Crystal structure and biochemical characterization of HYPO-SENSITIVE TO LIGHT 8 (ShHTL8) in strigolactone signaling pathway. Biochem Biophys Res Commun. 2020; 523(4): 1040–5. Yoshimura M, Sato A, Kuwata K, et al. Discovery of Shoot Branching Regulator Targeting Strigolactone Receptor DWARF14. Acs Cent Sci. 2018; 4(2): 230–4. Shabek N, Ticchiarelli F, Mao H, et al. Structural plasticity of D3–D14 ubiquitin ligase in strigolactone signalling. Nature. 2018; 563(7733): 652–6. Toh S, Holbrook-Smith D, Stogios P J, et al. Structure-function analysis identifies highly sensitive strigolactone receptors in Striga. Science. 2015; 350(6257): 203–7. Chevalier F, Nieminen K, Sánchez-Ferrero J C, et al. Strigolactone Promotes Degradation of DWARF14, an α/β Hydrolase Essential for Strigolactone Signaling inArabidopsis. Plant Cell. 2014; 26(3): 1134–50. Yao R, Ming Z, Yan L, et al. DWARF14 is a non-canonical hormone receptor for strigolactone. Nature. 2016; 536(7617): 469–73. Carlsson G H, Hasse D, Cardinale F, et al. The elusive ligand complexes of the DWARF14 strigolactone receptor. J Exp Bot. 2018; 69(9): 2345–54. Wang L, Wang B, Yu H, et al. Transcriptional regulation of strigolactone signalling in Arabidopsis. Nature. 2020; 583(7815): 277–81. Lu S Y, Jiang Y J, Lv J, et al. Molecular docking and molecular dynamics simulation studies of GPR40 receptor-agonist interactions. J Mol Graphis Modell. 2010; 28(8): 766–74. Sahu S N, Pattanayak S K. Molecular docking and molecular dynamics simulation studies on PLCE1 encoded protein. J Mol Struct. 2019; 1198(15): 126936. Lee K H, Piau H L, Kim H Y, et al. Activation of glucosidase via stress-induced polymerization rapidly increases active pools of abscisic acid. Cell. 2006; 126(6): 1109–20. Cao F Y, Yoshioka K, Desveaux D. The roles of ABA in plant-pathogen interactions. J Plant Res. 2011; 124(4): 489–99. Hagen G, Guilfoyle T J, Gray W M. Auxin Signal Transduction. Essays Biochem, 2015, 58(1): 282–307. Romanov G A. The discovery of cytokinin receptors and biosynthesis of cytokinins: A true story. Russ J Plant Physiol. 2011; 58(4): 743–7. Rizza A, Jones A M. The makings of a gradient: spatiotemporal distribution of gibberellins in plant development. Curr Opin Plant Biol. 2019; 47(1): 9–15. Additional Declarations No competing interests reported. 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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-6667656","acceptedTermsAndConditions":true,"allowDirectSubmit":true,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":460671111,"identity":"830d9c67-4cbd-4cf7-8510-95be7417276e","order_by":0,"name":"Linfeng Kai","email":"","orcid":"","institution":"Anhui Agricultural University","correspondingAuthor":false,"prefix":"","firstName":"Linfeng","middleName":"","lastName":"Kai","suffix":""},{"id":460671112,"identity":"e2d24ba1-21bc-41f9-8bcd-bf6b9927f13d","order_by":1,"name":"Chao Qin","email":"","orcid":"","institution":"Anhui Agricultural University","correspondingAuthor":false,"prefix":"","firstName":"Chao","middleName":"","lastName":"Qin","suffix":""},{"id":460671113,"identity":"fbb87c1d-03e5-4721-af3b-54fbb641399f","order_by":2,"name":"Hongfei He","email":"","orcid":"","institution":"Anhui Agricultural University","correspondingAuthor":false,"prefix":"","firstName":"Hongfei","middleName":"","lastName":"He","suffix":""},{"id":460671114,"identity":"3de55d96-ca71-481f-b54a-49c8b54963ef","order_by":3,"name":"Qing X. Li","email":"","orcid":"","institution":"University of Hawaii at Manoa","correspondingAuthor":false,"prefix":"","firstName":"Qing","middleName":"X.","lastName":"Li","suffix":""},{"id":460671115,"identity":"00696ab7-40e3-4a8c-9c16-3795a12013ad","order_by":4,"name":"Rimao Hua","email":"","orcid":"","institution":"Anhui Agricultural University","correspondingAuthor":false,"prefix":"","firstName":"Rimao","middleName":"","lastName":"Hua","suffix":""},{"id":460671116,"identity":"2d88a430-63d9-4b8f-8f5c-416478b94c6a","order_by":5,"name":"Pei Lv","email":"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAZAAAAAyAQMAAABI0h/eAAAABlBMVEX///8AAABVwtN+AAAACXBIWXMAAA7EAAAOxAGVKw4bAAAAwUlEQVRIiWNgGAWjYBACPhCRUMGQAObxEKOFDazlDMlaGNtI0iKRe/DBw3l2efwzEhgfvG1jkDcnrCUv2SBxW3KxxI0EZsO5bQyGOxsIaeE5YyaRuI05seFGAps0L9CFBgcIazH/kTinPnH+jQT238RpYe8xY0hsOJy4AWgLM5Fa+pIlEo4dT9x45mGz5JxzEoYbCGnhZ+Y9+PFHTXXivOPJBz+8KbORJ2gLUlwwNgAJCYLqGYiMvlEwCkbBKBjRAAB33T05KCw8iwAAAABJRU5ErkJggg==","orcid":"","institution":"Anhui Agricultural University","correspondingAuthor":true,"prefix":"","firstName":"Pei","middleName":"","lastName":"Lv","suffix":""}],"badges":[],"createdAt":"2025-05-15 00:38:10","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-6667656/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-6667656/v1","draftVersion":[],"editorialEvents":[],"editorialNote":"","failedWorkflow":false,"files":[{"id":83364268,"identity":"663828dc-8855-4777-8307-e296a5c817b8","added_by":"auto","created_at":"2025-05-23 18:32:12","extension":"png","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":25570,"visible":true,"origin":"","legend":"\u003cp\u003eChemical structures of representative natural and synthetic strigolactone mimics\u003c/p\u003e","description":"","filename":"Onlinefloatimage2.png","url":"https://assets-eu.researchsquare.com/files/rs-6667656/v1/d32b2d4cd9576850c7fd12e7.png"},{"id":83364271,"identity":"d546ac5d-9e83-426a-858d-391cb6757820","added_by":"auto","created_at":"2025-05-23 18:32:12","extension":"png","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":37647,"visible":true,"origin":"","legend":"\u003cp\u003eGeneral synthetic route for the target compounds.\u003c/p\u003e","description":"","filename":"Onlinefloatimage3.png","url":"https://assets-eu.researchsquare.com/files/rs-6667656/v1/e67c112cc4098517e34f4717.png"},{"id":83364276,"identity":"40a20d51-513a-42b6-8e7b-465ee11b4f7c","added_by":"auto","created_at":"2025-05-23 18:32:12","extension":"png","order_by":3,"title":"Figure 3","display":"","copyAsset":false,"role":"figure","size":146171,"visible":true,"origin":"","legend":"\u003cp\u003eDose effect of compounds \u003cstrong\u003e3s\u003c/strong\u003eand \u003cstrong\u003e4h\u003c/strong\u003e on (\u003cstrong\u003eA\u003c/strong\u003e) corn root and (\u003cstrong\u003eB\u003c/strong\u003e) corn bud germination.\u003c/p\u003e","description":"","filename":"Onlinefloatimage4.png","url":"https://assets-eu.researchsquare.com/files/rs-6667656/v1/bd388997b77e272d4b3ff557.png"},{"id":83364270,"identity":"9b83ecec-4008-437b-9ae1-71f1ad8a3fc3","added_by":"auto","created_at":"2025-05-23 18:32:12","extension":"png","order_by":4,"title":"Figure 4","display":"","copyAsset":false,"role":"figure","size":135284,"visible":true,"origin":"","legend":"\u003cp\u003eGrowth promotion rate (%) of \u003cstrong\u003e3s\u003c/strong\u003e and \u003cstrong\u003e4h\u003c/strong\u003e on corn plant height, aboveground biomass, and belowground biomass at concentrations of 10 mg/L (\u003cstrong\u003eA\u003c/strong\u003e) and100 mg/L (\u003cstrong\u003eB\u003c/strong\u003e). The error bar indicates the standard deviation from three biological replicates.\u003c/p\u003e","description":"","filename":"Onlinefloatimage5.png","url":"https://assets-eu.researchsquare.com/files/rs-6667656/v1/cecb7fca1e780b199683277d.png"},{"id":83364279,"identity":"f1688c5c-07d4-4f0f-a2f9-c06a2edbd9e3","added_by":"auto","created_at":"2025-05-23 18:32:12","extension":"png","order_by":5,"title":"Figure 5","display":"","copyAsset":false,"role":"figure","size":157825,"visible":true,"origin":"","legend":"\u003cp\u003eEffects of \u003cstrong\u003e3s\u003c/strong\u003e and \u003cstrong\u003e4h\u003c/strong\u003e on the content in corn endogenous hormones. Abscisic acid (A), gibberellin (A), auxin\u003cstrong\u003e \u003c/strong\u003e(B and C), cytokinin (D). The error bar indicates the standard deviation from three biological replicates.\u003c/p\u003e","description":"","filename":"Onlinefloatimage6.png","url":"https://assets-eu.researchsquare.com/files/rs-6667656/v1/4e580a2e918a02abb93f5572.png"},{"id":83364272,"identity":"bab5ce84-9b64-4157-9d6d-8cdff591fb4d","added_by":"auto","created_at":"2025-05-23 18:32:12","extension":"png","order_by":6,"title":"Figure 6","display":"","copyAsset":false,"role":"figure","size":323494,"visible":true,"origin":"","legend":"\u003cp\u003eMolecular docking results. (A) The three-dimensional structure of AtD14, (B) result of GR24, (C) result of 3s, (D) result of 4h.\u003c/p\u003e","description":"","filename":"Onlinefloatimage7.png","url":"https://assets-eu.researchsquare.com/files/rs-6667656/v1/964bfe91bc9e9a688d7be69e.png"},{"id":84242342,"identity":"34ffa81a-a8d4-4141-b92b-d634bd96f772","added_by":"auto","created_at":"2025-06-09 16:02:00","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":2317628,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-6667656/v1/30276011-5328-4cfc-839b-fbc53ee1ba18.pdf"},{"id":83364282,"identity":"70811fce-3c42-4a7b-9692-c7ea04d5fb4a","added_by":"auto","created_at":"2025-05-23 18:32:12","extension":"docx","order_by":1,"title":"","display":"","copyAsset":false,"role":"supplement","size":4673316,"visible":true,"origin":"","legend":"","description":"","filename":"SupportingInformation.docx","url":"https://assets-eu.researchsquare.com/files/rs-6667656/v1/309232d1ad18d607ef7e98a4.docx"},{"id":83364587,"identity":"ef8f4334-0217-4c61-8fc7-2cd3b7657b3d","added_by":"auto","created_at":"2025-05-23 18:40:12","extension":"png","order_by":2,"title":"","display":"","copyAsset":false,"role":"supplement","size":193375,"visible":true,"origin":"","legend":"","description":"","filename":"Onlinefloatimage1.png","url":"https://assets-eu.researchsquare.com/files/rs-6667656/v1/46a6316b7611c98119dff6d2.png"}],"financialInterests":"No competing interests reported.","formattedTitle":"Synthesis and Germination Activity of 5-(thio)phenol-3-methylfuran-2(5H)-one Analogues as Strigolactone Mimics","fulltext":[{"header":"Background","content":"\u003cp\u003eRoot parasitic weeds are a group of highly damaging weeds worldwide, of which \u003cem\u003eStriga\u003c/em\u003e and \u003cem\u003eOrobanche\u003c/em\u003e are the most widespread and damaging\u003csup\u003e[\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e]\u003c/sup\u003e. \u003cem\u003eStriga\u003c/em\u003e species are severe obligatory parasites of grain and cash crops such as soybean, sorghum, corn, and rice. Once these crops are parasitized, striga can drastically reduce yields or even induce crop damage\u003csup\u003e[\u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e, \u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e]\u003c/sup\u003e.\u003c/p\u003e \u003cp\u003eParasitic plants of the genera \u003cem\u003eStriga\u003c/em\u003e, \u003cem\u003ePhelipanche\u003c/em\u003e, and \u003cem\u003eOrobanche\u003c/em\u003e use strigolactones (SLs) in their root exudates to locate nearby hosts for growth and development\u003csup\u003e[\u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e]\u003c/sup\u003e. Small-molecule SLs acts endogenous plant hormones\u003csup\u003e[\u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e]\u003c/sup\u003e and have received great interest in current plant biology\u003csup\u003e[\u003cspan additionalcitationids=\"CR2 CR3 CR4 CR5\" citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e]\u003c/sup\u003e. In the past, many studies were focused on SL biology and achieved staggering progress, permitting a highly detailed understanding of their signaling, synthesis, and biological roles\u003csup\u003e[\u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e, \u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e]\u003c/sup\u003e. Recently, Gu et al.\u003csup\u003e[\u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e]\u003c/sup\u003e revealed a novel mechanism underlying crosstalk between SL and inorganic phosphate signaling networks in response to inorganic phosphate fluctuations. This would enable the breeding of crop plants with high phosphorus use efficiency. Ge et al.\u003csup\u003e[\u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e]\u003c/sup\u003e reported an efficient and practical synthetic route to assemble novel highly-tens[5,5] transfused B/C strigolactam/SL analogues along with cis-fused strigolactams. It was found that SLs could regulate plant development, such as promoting the germination of root parasitic weed seeds, elongating plant primary roots, increasing root hairs, inhibiting plant branching, and inducing plant senescence\u003csup\u003e[\u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e, \u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e11\u003c/span\u003e]\u003c/sup\u003e. Based on a structure\u0026ndash;activity relationship of SLs, the bioactiphore in this SL family of stimulants was deduced and found to reside in the D part of the stimulant molecule. Thus, a molecular mechanism was proposed for the initial stage of seed germination\u003csup\u003e[\u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e]\u003c/sup\u003e. Many SL derivatives have been designed and synthesized based on their molecular mechanisms, such as GR24, Nijmengen-1, and T-010 (Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003e)\u003csup\u003e[\u003cspan additionalcitationids=\"CR13 CR14\" citationid=\"CR12\" class=\"CitationRef\"\u003e12\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR15\" class=\"CitationRef\"\u003e15\u003c/span\u003e]\u003c/sup\u003e. However, existing mimics exhibit complex structures and low stability. Therefore, there is an urgent need for simple mimics that can maintain biological functions.\u003c/p\u003e \u003cp\u003eIn this paper, we developed two series of highly efficient and structurally simple novel mimics of natural SLs and their biological activities of promoting plant germination and growth were evaluated. Their modes of action were explored by analysis plant hormone response and molecular docking.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e"},{"header":"MATERIALS AND METHODS","content":"\u003cp\u003eInstruments and reagents\u003c/p\u003e \u003cp\u003e \u003csup\u003e1\u003c/sup\u003eH Nuclear magnetic resonance (NMR) and \u003csup\u003e13\u003c/sup\u003eC NMR spectra were obtained at 25\u0026deg;C using an Agilent DD2 AV-600 NMR spectrometer. Tetramethylsilane (TMS) was used as an internal standard. Dimethyl sulfoxide (DMSO-\u003cem\u003ed\u003c/em\u003e\u003csub\u003e\u003cem\u003e6\u003c/em\u003e\u003c/sub\u003e) and deuterated chloroform (CDCl\u003csub\u003e3)\u003c/sub\u003e were used as solvents. High-resolution mass spectrometry (HR-MS) data were obtained using a high-resolution Varian quantum field theory-electrospray ionization mass spectrometer (QFT-ESI). Melting points were recorded on an XT4 MP apparatus (Taike Co., Beijing, China) and uncorrected. During synthesis, all reagents and solvents (Shanghai Aladdin Biochemical Technology Co., Ltd.) were used as received. Seeds for bioactivity experiments were provided by the College of Resources and Environment of Anhui Agricultural University. During hormone measurement, high-performance liquid chromatography (HPLC) grade acetonitrile (ACN) and methanol (MeOH) were purchased from Merck (Darmstadt, Germany). MilliQ water (Millipore, Bradford, USA) was used in all experiments. All standards were purchased from Olchemim Ltd. (Olomouc, Czech Republic) and isoReag (Shanghai, China). Acetic acid and formic acid were purchased from Sigma-Aldrich (St Louis, MO, USA). Stock solutions of the standards were prepared at a concentration of 1 mg/mL in MeOH. All stock solutions were stored at -20\u0026deg;C. The stock solutions were diluted with MeOH to working solutions before analysis.\u003c/p\u003e \u003cp\u003eSynthesis of target compounds\u003c/p\u003e \u003cp\u003e \u003cb\u003eSynthesis of 5-hydroxy-3-methylfuran-2 (5\u003c/b\u003e \u003cb\u003eH\u003c/b\u003e \u003cb\u003e)-one (1)\u003c/b\u003e. A total of 10 drops of sulfuric Acid (H\u003csub\u003e2\u003c/sub\u003eSO\u003csub\u003e4)\u003c/sub\u003e were added to a solution of methylmalonic acid (7.00 g, 59.3 mmol) and glyoxal (3.4 g, 59.3 mmol) in H\u003csub\u003e2\u003c/sub\u003eO (60 mL). The mixture was stirred at 110\u0026deg;C for 12 h. Then, sodium chloride (NaCl) was added to the mixture to saturation at room temperature and extracted three times with ethyl acetate (EtOAc). The combined organic layers were dried over Sodium Sulfate (Na\u003csub\u003e2\u003c/sub\u003eSO\u003csub\u003e4\u003c/sub\u003e), filtered, and concentrated. The residue was purified by silica gel column chromatography to afford 5-hydroxy-3-methylfuran-2(5\u003cem\u003eH\u003c/em\u003e)-one as a solid (3.15 g, 46%).\u003c/p\u003e \u003cp\u003e \u003cb\u003eSynthesis of 5-chloro-3-methylfuran-2(5\u003c/b\u003e \u003cb\u003eH\u003c/b\u003e \u003cb\u003e)-one (2)\u003c/b\u003e. Thionyl chloride (SOCl\u003csub\u003e2\u003c/sub\u003e) (1.2 mL, 16.5 mmol) and N, N-dimethylformamide (DMF) (160 \u0026micro;L, 2.07 mmol) were charged in a flask. A solution of 5-hydroxy-3-methylfuran-2(5\u003cem\u003eH\u003c/em\u003e)-one (3.15 g, 27.64 mmol) in a minimum amount of dichloromethane (CH\u003csub\u003e2\u003c/sub\u003eCl\u003csub\u003e2\u003c/sub\u003e) (4 mL) was added to the above mixture. The mixture was stirred at 90\u0026deg;C for 10 min and cooled to room temperature. Then, the mixture was diluted with CH\u003csub\u003e2\u003c/sub\u003eCl\u003csub\u003e2\u003c/sub\u003e-hexane (1:1) and quenched with sat. aq. sodium bicarbonate (NaHCO\u003csub\u003e3\u003c/sub\u003e) at 0\u0026deg;C. The mixture was extracted three times with CH\u003csub\u003e2\u003c/sub\u003eCl\u003csub\u003e2\u003c/sub\u003e-hexane (1:4). The combined organic layers were washed with brine, dried over Na\u003csub\u003e2\u003c/sub\u003eSO\u003csub\u003e4\u003c/sub\u003e, filtered, and concentrated. The residue was purified by silica gel column chromatography (10\u0026ndash;20% EtOAc/hexane) to afford 5-chloro-3-methylfuran-2(\u003cem\u003e5H\u003c/em\u003e)-one as a yellowish oil (1.76 g, 47%).\u003c/p\u003e \u003cp\u003e \u003cb\u003eGeneral procedure to prepare novel strigolactone mimics (3a-3y)\u003c/b\u003e. Phenols (1.89 mmol), 4A molecular sieve (1 g), potassium iodide (31 mg, 0.189 mmol), and tetrahydrofuran (20 mL) were stirred under a nitrogen atmosphere. Potassium tert-butoxide (2 mL of a 1.0 M solution in tert-butanol, 2 mmol) was introduced with cooling (ice bath) and the mixture was stirred for 10 min. Then, fresh compound 2 (250 mg, 1.89 mmol) was added and the reaction mixture was stirred for 3 h. Next, water (10 mL) was added. The product was extracted three times with EtOAc (25 mL) and dried over anhydrous Magnesium Sulfate (MgSO\u003csub\u003e4\u003c/sub\u003e). The residue was purified by silica gel column chromatography to afford \u003cb\u003e3a\u003c/b\u003e-\u003cb\u003e3y\u003c/b\u003e. The physical data for \u003cb\u003e3a\u003c/b\u003e-\u003cb\u003e3y\u003c/b\u003e are provided in the Supporting Information.\u003c/p\u003e \u003cp\u003e \u003cb\u003eGeneral procedure to prepare novel strigolactone mimics\u003c/b\u003e (\u003cb\u003e4a-4i\u003c/b\u003e). Thiophenols (1.89 mmol), 4A molecular sieve (1 g), and potassium iodide (31 mg, 0.189 mmol) were added to a dry round-bottomed flask containing tetrahydrofuran (20 mL) under N\u003csub\u003e2\u003c/sub\u003e. Potassium tert-butoxide (2 mL of a 1.0 M solution in tert-butanol, 2 mmol) was introduced with cooling (ice bath) and the mixture was stirred for 10 min. Then, fresh compound 2 (250 mg, 1.89 mmol) was added, and the reaction mixture was stirred for 3 h. Next, water (10 mL) was added. The product was extracted three times with EtOAc (25 mL) and dried over anhydrous Mg\u003csub\u003e2\u003c/sub\u003eSO\u003csub\u003e4\u003c/sub\u003e. The residue was purified by silica gel column chromatography to afford \u003cb\u003e4a\u003c/b\u003e-\u003cb\u003e4i\u003c/b\u003e. The physical data for \u003cb\u003e4a\u003c/b\u003e-\u003cb\u003e4i\u003c/b\u003e are provided in the Supporting Information.\u003c/p\u003e \u003cp\u003eBiological assay\u003c/p\u003e \u003cp\u003eAccording to the methodology described by Theologidou \u003cem\u003eet al.\u003c/em\u003e,\u003csup\u003e[\u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e16\u003c/span\u003e]\u003c/sup\u003e we employed the Petri dish method for the preliminary screening of the germination activity of target compounds. Based on the preliminary screening results, we selected two of the most effective compounds (\u003cb\u003e3s\u003c/b\u003e and \u003cb\u003e4h\u003c/b\u003e) and measured their growth promotion rates on corn root/bud length at a concentration gradient of 0.01mg/L to 100mg/L to determine their dose effect. Subsequently, pot experiments were conducted to systematically assess the impact of compounds \u003cb\u003e3s\u003c/b\u003e and \u003cb\u003e4h\u003c/b\u003e at concentrations of 10 mg/L and 100 mg/L on key agronomic traits of corn, including plant height, aboveground biomass, and belowground biomass. Thereby, this can provide a comprehensive evaluation of their growth-promoting efficacy. The specific operational steps for the biological assay are provided in the Supporting Information.\u003c/p\u003e \u003cp\u003eMechanism of action of target compounds\u003c/p\u003e \u003cdiv id=\"Sec3\" class=\"Section2\"\u003e \u003ch2\u003eDetermination of growth hormone content\u003c/h2\u003e \u003cp\u003eCorn seeds were grown for three days by the petri dish bioassay method and used as the test material. \u003cb\u003e3s\u003c/b\u003e and \u003cb\u003e4h\u003c/b\u003e were used as test agents. Pure water was used as a blank control (CK). The mechanism of the target compound in promoting plant growth and development was further investigated.\u003c/p\u003e \u003c/div\u003e\n\u003ch3\u003eSample preparation and extraction\u003c/h3\u003e\n\u003cp\u003eCorn seeds with similar growth conditions were selected and soaked in 1% sodium hypochlorite and 75% ethanol for 2 min for surface disinfection. The seeds were rinsed thoroughly with disinfected deionized water and then dried naturally. Two layers of 9 cm glass fiber filter paper were placed at the bottom of a culture dish moistened with sterile water. Corn seeds were evenly sprinkled on the glass fiber filter paper. Next, 1mL of the prepared 10 mg/L \u003cb\u003e3s\u003c/b\u003e and \u003cb\u003e4h\u003c/b\u003e was sprayed into the culture dish. Usually, each culture dish contained 10 seeds. The culture dish was placed in a constant temperature incubator to allow the seeds to grow at 24\u0026deg;C for 3 days with a photoperiod of 12 h in order to obtain fresh solid corn samples. Fresh corn samples after \u003cb\u003e3s\u003c/b\u003e and \u003cb\u003e4h\u003c/b\u003e treatments were harvested, immediately frozen in liquid nitrogen, ground into powder (30 Hz, 1 min), and stored at -80\u0026deg;C until needed. 50 mg of plant sample was weighed into a 2 mL plastic microtube, frozen in liquid nitrogen, and dissolved in 1 mL methanol/water/formic acid (15:4:1, V/V/V). 10 \u0026micro;L of an internal standard mixed solution (100 ng/mL) was added into the extract as an internal standard (IS) for quantitative analysis. The mixture was vortexed for 10 min and then centrifuged for 5 min (12000 r/min, and 4\u0026deg;C). The supernatant was transferred to clean plastic microtubes, evaporated to dryness, dissolved in 100 \u0026micro;L of 80% methanol (V/V), and filtered through a 0.22 \u0026micro;m membrane filter for further Liquid Chromatography-Tandem Mass Spectrometry (LC-MS/MS) analysis\u003csup\u003e[\u003cspan citationid=\"CR17\" class=\"CitationRef\"\u003e17\u003c/span\u003e, \u003cspan citationid=\"CR18\" class=\"CitationRef\"\u003e18\u003c/span\u003e]\u003c/sup\u003e.\u003c/p\u003e\n\u003ch3\u003eUPLC conditions\u003c/h3\u003e\n\u003cp\u003eSample extracts were analyzed using an UPLC-ESI-MS/MS system (UPLC, ExionLC\u0026trade; AD, \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://sciex.com.cn/\u003c/span\u003e\u003cspan address=\"https://sciex.com.cn/\" targettype=\"URL\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e; MS, QTRAP\u0026reg; 6500+, \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://sciex.com.cn/\u003c/span\u003e\u003cspan address=\"https://sciex.com.cn/\" targettype=\"URL\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e). The analytical conditions were as follows: LC, Waters ACQUITY UPLC HSS T3 C18 columns (100 mm\u0026times;2.1 mm i.d, 1.8 \u0026micro;m); solvent systems, water with 0.04% acetic acid (A) and acetonitrile with 0.04% acetic acid (B); gradient program, starting at 5% B (0\u0026ndash;1 min), increasing to 95% B (1\u0026ndash;8 min), 95% B (8\u0026ndash;9 min) and finally ramping back to 5% B (9.1\u0026ndash;12 min); flow rate, 0.35 mL/min; temperature, 40\u0026deg;C; injection volume, 2 \u0026micro;L\u003csup\u003e[\u003cspan additionalcitationids=\"CR20\" citationid=\"CR19\" class=\"CitationRef\"\u003e19\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR21\" class=\"CitationRef\"\u003e21\u003c/span\u003e]\u003c/sup\u003e.\u003c/p\u003e\n\u003ch3\u003eESI-MS/MS conditions\u003c/h3\u003e\n\u003cp\u003eLinear ion trap (LIT) and triple quadrupole (QQQ) scans were acquired on a triple quadrupole-linear ion trap mass spectrometer (QTRAP) (QTRAP\u003csup\u003e\u0026reg;\u003c/sup\u003e 6500\u0026thinsp;+\u0026thinsp;LC-MS/MS System). This system was equipped with an ESI Turbo Ion-Spray interface, operated in both positive and negative ion mode, and was controlled by Analyst 1.6.3 software (Sciex). The ESI source operation parameters were as follows: ion source, ESI+/-; source temperature, 550 ℃; ion spray voltage (IS), 5500 V (Positive)and \u0026minus;\u0026thinsp;4500 V (Negative); curtain gas (CUR), 35 psi. Phytohormones were analyzed using scheduled multiple reaction monitoring (MRM). Data acquisitions were performed using Analyst 1.6.3 software (Sciex). All metabolites were quantified using Multiquant 3.0.3 software (Sciex). Mass spectrometer parameters, including declustering potential (DP) and collision energies (CE) of individual MRM transitions, were further optimized. A specific set of MRM transitions was monitored for each period according to the metabolites eluted within this period\u003csup\u003e[\u003cspan additionalcitationids=\"CR23\" citationid=\"CR22\" class=\"CitationRef\"\u003e22\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR24\" class=\"CitationRef\"\u003e24\u003c/span\u003e]\u003c/sup\u003e.\u003c/p\u003e \u003cp\u003eMolecular docking\u003c/p\u003e \u003cp\u003eThe structures of SL receptor proteins derived from Arabidopsis (AtD14), petunia (DAD2), rice (OsD14), and solanum (ShHTLs) species have been resolved\u003csup\u003e[\u003cspan additionalcitationids=\"CR26 CR27\" citationid=\"CR25\" class=\"CitationRef\"\u003e25\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR28\" class=\"CitationRef\"\u003e28\u003c/span\u003e]\u003c/sup\u003e. Structurally, their overall structures have a high degree of similarity in different species of plants \u003csup\u003e[\u003cspan citationid=\"CR29\" class=\"CitationRef\"\u003e29\u003c/span\u003e]\u003c/sup\u003e.Therefore, AtD14 (PDB: 4IH4) was selected as the receptor protein for docking experiments. AutoDock was used to perform molecular docking between the target compounds and the SL receptor protein DWARF14 (AtD14) in order to explore the mechanism of action of the target compounds. GR24 was selected as the positive control, and the compounds \u003cb\u003e3s\u003c/b\u003e and \u003cb\u003e4h\u003c/b\u003e with the best activity assay were selected as small-molecule ligands\u003csup\u003e[\u003cspan additionalcitationids=\"CR31\" citationid=\"CR30\" class=\"CitationRef\"\u003e30\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR32\" class=\"CitationRef\"\u003e32\u003c/span\u003e]\u003c/sup\u003e. All twist angles in small molecules were released for flexible docking. Water molecules were removed from AtD14 using the AutoDock Tool, and the hydrogen module was added. On this basis, the charge distribution of small-molecule ligands was assigned\u003csup\u003e[\u003cspan citationid=\"CR33\" class=\"CitationRef\"\u003e33\u003c/span\u003e, \u003cspan citationid=\"CR34\" class=\"CitationRef\"\u003e34\u003c/span\u003e]\u003c/sup\u003e.\u003c/p\u003e \u003cp\u003eIn the binding mode with AtD14, the binding sites of ligands on AtD14 are mainly located near amino acid residues in proteins, such as Ser97, His247, and Asp218. Therefore, the docking box was set to encapsulate all abovementioned active sites. The empirical free energy function and Lamarckian genetic algorithm (LGA) were used for docking, with the following settings: a maximum number of energy evaluations of 30,000,000, an initial population of 150 randomly placed individuals, a maximum number of generations of 27,000, a mutation rate of 0.02, a crossover rate of 0.80 and an automatic survival (maximum number of top individuals) of 1.A total of 50 docking attempts were made for each ligand.\u003c/p\u003e"},{"header":"Results And Discussion","content":"\u003cdiv id=\"Sec8\" class=\"Section2\"\u003e \u003ch2\u003eSynthesis of strigolactone mimics\u003c/h2\u003e \u003cp\u003eThe synthesis of SL mimics began with 2-methylpropanedioic acid (Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003e). The intermediate 5-hydroxy-3-methylfuran-2(\u003cem\u003e5H\u003c/em\u003e)-one was obtained via the cyclization of methylpropanedioic acid with glyoxal. The target phenolic derivatives (\u003cb\u003e3a\u003c/b\u003e-\u003cb\u003e3y\u003c/b\u003e) and thiophenolic derivatives (\u003cb\u003e4a\u003c/b\u003e-\u003cb\u003e4i\u003c/b\u003e) were successfully obtained via chlorination of hydroxy groups followed by nucleophilic substitution.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003c/div\u003e\n\u003ch3\u003eBiological assays\u003c/h3\u003e\n\u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab1\" border=\"1\"\u003e \u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 1\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003ePromotion germination activity of \u003cb\u003e3a\u003c/b\u003e-\u003cb\u003e3y\u003c/b\u003e, \u003cb\u003e4a\u003c/b\u003e-\u003cb\u003e4i\u003c/b\u003e on corn and sorghum seed germination at 100 mg/L\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"10\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c5\" colnum=\"5\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c6\" colnum=\"6\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c7\" colnum=\"7\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c8\" colnum=\"8\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c9\" colnum=\"9\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c10\" colnum=\"10\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/th\u003e \u003cth align=\"left\" colspan=\"9\" nameend=\"c10\" namest=\"c2\"\u003e \u003cp\u003eGrowth promotion rate\u003csup\u003e\u003cem\u003e\u0026dagger;\u003c/em\u003e\u003c/sup\u003e (%)\u0026thinsp;\u0026plusmn;\u0026thinsp;SD\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\" morerows=\"1\" rowspan=\"2\"\u003e \u003cp\u003eCmpd\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colspan=\"2\" nameend=\"c3\" namest=\"c2\"\u003e \u003cp\u003eCorn\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colspan=\"2\" nameend=\"c5\" namest=\"c4\"\u003e \u003cp\u003eSorghum\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\" morerows=\"1\" rowspan=\"2\"\u003e \u003cp\u003eCmpd\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colspan=\"2\" nameend=\"c8\" namest=\"c7\"\u003e \u003cp\u003eCorn\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colspan=\"2\" nameend=\"c10\" namest=\"c9\"\u003e \u003cp\u003eSorghum\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eroot\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003ebud\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003eroot\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003ebud\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003eroot\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003ebud\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c9\"\u003e \u003cp\u003eroot\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c10\"\u003e \u003cp\u003ebud\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003e3a\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e7\u0026thinsp;\u0026plusmn;\u0026thinsp;1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e12\u0026thinsp;\u0026plusmn;\u0026thinsp;1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e24\u0026thinsp;\u0026plusmn;\u0026thinsp;1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e21\u0026thinsp;\u0026plusmn;\u0026thinsp;1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e\u003cb\u003e3r\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e34\u0026thinsp;\u0026plusmn;\u0026thinsp;2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003e50\u0026thinsp;\u0026plusmn;\u0026thinsp;2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c9\"\u003e \u003cp\u003e32\u0026thinsp;\u0026plusmn;\u0026thinsp;2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c10\"\u003e \u003cp\u003e48\u0026thinsp;\u0026plusmn;\u0026thinsp;3\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003e3b\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e27\u0026thinsp;\u0026plusmn;\u0026thinsp;3\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e30\u0026thinsp;\u0026plusmn;\u0026thinsp;2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e32\u0026thinsp;\u0026plusmn;\u0026thinsp;2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e38\u0026thinsp;\u0026plusmn;\u0026thinsp;1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e\u003cb\u003e3s\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e 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\u003cp\u003e1\u0026thinsp;\u0026plusmn;\u0026thinsp;1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c10\"\u003e \u003cp\u003e30\u0026thinsp;\u0026plusmn;\u0026thinsp;1\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003e3k\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e29\u0026thinsp;\u0026plusmn;\u0026thinsp;2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e32\u0026thinsp;\u0026plusmn;\u0026thinsp;2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e16\u0026thinsp;\u0026plusmn;\u0026thinsp;2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e30\u0026thinsp;\u0026plusmn;\u0026thinsp;2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e\u003cb\u003e4c\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e-12\u0026thinsp;\u0026plusmn;\u0026thinsp;2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003e-24\u0026thinsp;\u0026plusmn;\u0026thinsp;2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c9\"\u003e \u003cp\u003e-8\u0026thinsp;\u0026plusmn;\u0026thinsp;1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c10\"\u003e \u003cp\u003e6\u0026thinsp;\u0026plusmn;\u0026thinsp;1\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003e3l\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e9\u0026thinsp;\u0026plusmn;\u0026thinsp;1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e26\u0026thinsp;\u0026plusmn;\u0026thinsp;2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e8\u0026thinsp;\u0026plusmn;\u0026thinsp;1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e26\u0026thinsp;\u0026plusmn;\u0026thinsp;1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e\u003cb\u003e4d\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e12\u0026thinsp;\u0026plusmn;\u0026thinsp;1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003e14\u0026thinsp;\u0026plusmn;\u0026thinsp;1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c9\"\u003e \u003cp\u003e15\u0026thinsp;\u0026plusmn;\u0026thinsp;1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c10\"\u003e \u003cp\u003e-5\u0026thinsp;\u0026plusmn;\u0026thinsp;1\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003e3m\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e8\u0026thinsp;\u0026plusmn;\u0026thinsp;1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e24\u0026thinsp;\u0026plusmn;\u0026thinsp;1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e33\u0026thinsp;\u0026plusmn;\u0026thinsp;2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e36\u0026thinsp;\u0026plusmn;\u0026thinsp;2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e\u003cb\u003e4e\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e24\u0026thinsp;\u0026plusmn;\u0026thinsp;1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003e26\u0026thinsp;\u0026plusmn;\u0026thinsp;1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c9\"\u003e \u003cp\u003e-4\u0026thinsp;\u0026plusmn;\u0026thinsp;1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c10\"\u003e \u003cp\u003e-9\u0026thinsp;\u0026plusmn;\u0026thinsp;1\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003e3n\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e5\u0026thinsp;\u0026plusmn;\u0026thinsp;1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e11\u0026thinsp;\u0026plusmn;\u0026thinsp;1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e18\u0026thinsp;\u0026plusmn;\u0026thinsp;1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e12\u0026thinsp;\u0026plusmn;\u0026thinsp;1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e\u003cb\u003e4f\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e-1\u0026thinsp;\u0026plusmn;\u0026thinsp;1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003e-9\u0026thinsp;\u0026plusmn;\u0026thinsp;1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c9\"\u003e \u003cp\u003e5\u0026thinsp;\u0026plusmn;\u0026thinsp;1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c10\"\u003e \u003cp\u003e-2\u0026thinsp;\u0026plusmn;\u0026thinsp;1\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003e3o\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e18\u0026thinsp;\u0026plusmn;\u0026thinsp;1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e24\u0026thinsp;\u0026plusmn;\u0026thinsp;2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e30\u0026thinsp;\u0026plusmn;\u0026thinsp;2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e45\u0026thinsp;\u0026plusmn;\u0026thinsp;3\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e\u003cb\u003e4g\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e26\u0026thinsp;\u0026plusmn;\u0026thinsp;2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003e42\u0026thinsp;\u0026plusmn;\u0026thinsp;1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c9\"\u003e \u003cp\u003e6\u0026thinsp;\u0026plusmn;\u0026thinsp;1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c10\"\u003e \u003cp\u003e16\u0026thinsp;\u0026plusmn;\u0026thinsp;1\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003e3p\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e-3\u0026thinsp;\u0026plusmn;\u0026thinsp;1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e18\u0026thinsp;\u0026plusmn;\u0026thinsp;1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e17\u0026thinsp;\u0026plusmn;\u0026thinsp;1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e37\u0026thinsp;\u0026plusmn;\u0026thinsp;2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e\u003cb\u003e4h\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e46\u0026thinsp;\u0026plusmn;\u0026thinsp;2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003e63\u0026thinsp;\u0026plusmn;\u0026thinsp;3\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c9\"\u003e \u003cp\u003e51\u0026thinsp;\u0026plusmn;\u0026thinsp;3\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c10\"\u003e \u003cp\u003e62\u0026thinsp;\u0026plusmn;\u0026thinsp;1\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003e3q\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e13\u0026thinsp;\u0026plusmn;\u0026thinsp;1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e22\u0026thinsp;\u0026plusmn;\u0026thinsp;1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e29\u0026thinsp;\u0026plusmn;\u0026thinsp;2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e46\u0026thinsp;\u0026plusmn;\u0026thinsp;2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e\u003cb\u003e4i\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e23\u0026thinsp;\u0026plusmn;\u0026thinsp;1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003e40\u0026thinsp;\u0026plusmn;\u0026thinsp;1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c9\"\u003e \u003cp\u003e24\u0026thinsp;\u0026plusmn;\u0026thinsp;1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c10\"\u003e \u003cp\u003e31\u0026thinsp;\u0026plusmn;\u0026thinsp;1\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eGR24\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e25\u0026thinsp;\u0026plusmn;\u0026thinsp;2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e30\u0026thinsp;\u0026plusmn;\u0026thinsp;1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e29\u0026thinsp;\u0026plusmn;\u0026thinsp;1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e35\u0026thinsp;\u0026plusmn;\u0026thinsp;2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e\u003cb\u003eGR24\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e25\u0026thinsp;\u0026plusmn;\u0026thinsp;2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003e30\u0026thinsp;\u0026plusmn;\u0026thinsp;1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c9\"\u003e \u003cp\u003e29\u0026thinsp;\u0026plusmn;\u0026thinsp;1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c10\"\u003e \u003cp\u003e35\u0026thinsp;\u0026plusmn;\u0026thinsp;2\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e \u003cp\u003e \u003csup\u003e \u003cem\u003e\u0026dagger;\u003c/em\u003e \u003c/sup\u003e Root/Bud growth promotion rate of Corn and Sorghum plants via the Petri dish method.\u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab2\" border=\"1\"\u003e \u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 2\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003ePromotion germination activity of \u003cb\u003e3a\u003c/b\u003e-\u003cb\u003e3y\u003c/b\u003e, \u003cb\u003e4a\u003c/b\u003e-\u003cb\u003e4i\u003c/b\u003e on soybean and sunflower seed germination at 100 mg/L\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"6\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c5\" colnum=\"5\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c6\" colnum=\"6\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colspan=\"6\" nameend=\"c6\" namest=\"c1\"\u003e \u003cp\u003eGrowth promotion rate\u003csup\u003e\u003cem\u003e\u0026dagger;\u003c/em\u003e\u003c/sup\u003e (%)\u0026thinsp;\u0026plusmn;\u0026thinsp;SD\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\" morerows=\"1\" rowspan=\"2\"\u003e \u003cp\u003eCompd.\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003esoybean\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003esunflower\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\" morerows=\"1\" rowspan=\"2\"\u003e \u003cp\u003eCompd.\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003esoybean\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003eSunflower\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eroot\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eroot\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003eroot\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003eroot\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003e3a\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e-7\u0026thinsp;\u0026plusmn;\u0026thinsp;1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e12\u0026thinsp;\u0026plusmn;\u0026thinsp;1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e\u003cb\u003e3r\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e46\u0026thinsp;\u0026plusmn;\u0026thinsp;2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e32\u0026thinsp;\u0026plusmn;\u0026thinsp;2\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003e3b\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e-15\u0026thinsp;\u0026plusmn;\u0026thinsp;3\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e24\u0026thinsp;\u0026plusmn;\u0026thinsp;2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e\u003cb\u003e3s\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e 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\u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e17\u0026thinsp;\u0026plusmn;\u0026thinsp;1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e\u003cb\u003e4h\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e71\u0026thinsp;\u0026plusmn;\u0026thinsp;2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e68\u0026thinsp;\u0026plusmn;\u0026thinsp;3\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003e3q\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e26\u0026thinsp;\u0026plusmn;\u0026thinsp;1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e-10\u0026thinsp;\u0026plusmn;\u0026thinsp;2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e\u003cb\u003e4i\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e25\u0026thinsp;\u0026plusmn;\u0026thinsp;1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e24\u0026thinsp;\u0026plusmn;\u0026thinsp;1\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eGR24\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e32\u0026thinsp;\u0026plusmn;\u0026thinsp;2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e28\u0026thinsp;\u0026plusmn;\u0026thinsp;1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e\u003cb\u003eGR24\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e32\u0026thinsp;\u0026plusmn;\u0026thinsp;2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e28\u0026thinsp;\u0026plusmn;\u0026thinsp;1\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e \u003cp\u003e \u003csup\u003e \u003cem\u003e\u0026dagger;\u003c/em\u003e \u003c/sup\u003eRoot growth promotion rate of soybean and sunflower plants via the Petri dish method.\u003c/p\u003e \u003cp\u003eThe length-promoting potential of compounds \u003cb\u003e3a\u003c/b\u003e-\u003cb\u003e3y\u003c/b\u003e and \u003cb\u003e4a\u003c/b\u003e-\u003cb\u003e4i\u003c/b\u003e was preliminarily evaluated through a root/bud growth rate assay at 100 mg/L. This screening specifically targeted both dicotyledonous and monocotyledonous plant species that express SL receptor proteins, aiming to identify candidate compounds capable of activating SL-mediated growth regulatory pathways. (Tables\u0026nbsp;\u003cspan refid=\"Tab1\" class=\"InternalRef\"\u003e1\u003c/span\u003e and \u003cspan refid=\"Tab2\" class=\"InternalRef\"\u003e2\u003c/span\u003e). At 100 mg/L, most target compounds exhibited significantly promoting effects on corn and sorghum roots (5%-46%, 1%-51%) and bud (3%-63%, 6%-62%) growth. For dicotyledonous plants, most target compounds showed promoting effects on soybean root (4%-71%) and sunflower root (3%-68%). We found that when the SL mimics were 4-substituted phenoxyfuranone derivatives, they significantly promoted plant growth, and the property of the activity depended on substituent groups on the phenoxy group. The promotion activity was greater when the substituent was a halogenated element, such as bromine \u003cb\u003e(3b\u003c/b\u003e), chlorine (\u003cb\u003e3c\u003c/b\u003e), or fluorine (\u003cb\u003e3f\u003c/b\u003e), and higher when the substituents were electron-donating groups, such as methyl (\u003cb\u003e3q\u003c/b\u003e), ethyl (\u003cb\u003e3r\u003c/b\u003e) than that of electron-withdrawing groups, such as nitro (\u003cb\u003e3h\u003c/b\u003e). The promotion activities are not obviously changes when benzene ring was replaced by biphenyl (\u003cb\u003e3m\u003c/b\u003e), naphthalene (\u003cb\u003e3o\u003c/b\u003e), pyridine (\u003cb\u003e3p\u003c/b\u003e), isoquinoline (\u003cb\u003e3t)\u003c/b\u003e. Finally, based on the principle of bioisosterism, we found that replacing phenoxy groups with phenthio groups of SL mimics increased the activity of most compounds to varying degrees. Studying the conformational relationship of the compounds synthesized in this paper may facilitate the future design of SL mimics.\u003c/p\u003e \u003cp\u003eNext, in order to screen for the optimal concentration of compounds that promote corn germination, \u003cb\u003e3s\u003c/b\u003e and \u003cb\u003e4h\u003c/b\u003e were selected in the preliminary bioactivity assay (Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003e). We found that the greatest promotion rate on corn root and bud growth was achieved at a concentration of 10 mg/L, the promoting effect decreased as the concentrations increased and decreased.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eThen, in order to investigate the promoting effect of the target compounds on the entire plant, we further determined the effects of \u003cb\u003e3s\u003c/b\u003e and \u003cb\u003e4h\u003c/b\u003e on corn at concentrations of 10 and 100 mg/L using GR24 as a positive control in pot experiments (Fig.\u0026nbsp;\u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e4\u003c/span\u003e). \u003cb\u003e3s\u003c/b\u003e and \u003cb\u003e4h\u003c/b\u003e had significant effects on aboveground biomass, belowground biomass, and plant height of corn. Particularly, the effects on aboveground biomass were significantly higher than those on belowground biomass. This finding is consistent with previous petri dish experiments. \u003cb\u003e4h\u003c/b\u003e was the most effective at 10 mg/L, more than doubling the effect on aboveground biomass.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e\n\u003ch3\u003eMechanism of promotion effect on germination\u003c/h3\u003e\n\u003cp\u003eWe investigated the hormone levels in corn seeds treated with \u003cb\u003e3s\u003c/b\u003e and \u003cb\u003e4h\u003c/b\u003e at 10 mg/L during germination and conducted molecular docking between the compounds and AtD14 in order to preliminarily explore the mechanism of action. The abscisic acid content decreased by 9.3% and 13.7% in corn treated with \u003cb\u003e3s\u003c/b\u003e and \u003cb\u003e4s\u003c/b\u003e, respectively. The ABA glucosyl ester content in corn significantly increased (Fig.\u0026nbsp;\u003cspan refid=\"Fig5\" class=\"InternalRef\"\u003e5\u003c/span\u003eA). 3-Indole acetonitrile was not found in the control (CK). In contrast, the level of 3-Indole acetonitrile was 0.28 and 0.30 ng/g after \u003cb\u003e3s\u003c/b\u003e and \u003cb\u003e4h\u003c/b\u003e treatment. The content of 3-Indole amide increased by 8 times and 21 times under \u003cb\u003e3s\u003c/b\u003e and \u003cb\u003e4h\u003c/b\u003e, respectively (Fig.\u0026nbsp;\u003cspan refid=\"Fig5\" class=\"InternalRef\"\u003e5\u003c/span\u003eB). The content of L-tryptophan and indole under \u003cb\u003e3s\u003c/b\u003e increased by 6.5% and 12.1%, respectively. The content of L-tryptophan and Indole under \u003cb\u003e4h\u003c/b\u003e increased by 14.9% and 20.0%, respectively (Fig.\u0026nbsp;\u003cspan refid=\"Fig5\" class=\"InternalRef\"\u003e5\u003c/span\u003eC). The cytokinin content also increased under \u003cb\u003e3s\u003c/b\u003e and \u003cb\u003e4h\u003c/b\u003e treatment. N6-Isopentenyl-adenine-7-glucoside, trans-Zeatin-O-glucoside, and trans-Zeatin-9-glucoside increased by 41.1%, 13.5%, and 12.2% under \u003cb\u003e3s\u003c/b\u003e and by 31.5%, 32.5%, and 15.8% under \u003cb\u003e4h\u003c/b\u003e, respectively (Fig.\u0026nbsp;\u003cspan refid=\"Fig5\" class=\"InternalRef\"\u003e5\u003c/span\u003eD). Gibberellin A53 increased by 40.6% under \u003cb\u003e3s\u003c/b\u003e and 50.3% under \u003cb\u003e4h\u003c/b\u003e (Fig.\u0026nbsp;\u003cspan refid=\"Fig5\" class=\"InternalRef\"\u003e5\u003c/span\u003eA).\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab3\" border=\"1\"\u003e \u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 3\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003eMolecular docking of AtD14 protein with GR24, \u003cb\u003e3s\u003c/b\u003e and \u003cb\u003e4h\u003c/b\u003e\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"7\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c5\" colnum=\"5\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c6\" colnum=\"6\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c7\" colnum=\"7\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colspan=\"2\" nameend=\"c2\" namest=\"c1\"\u003e \u003cp\u003eLigands\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003eBinding energy\u003c/p\u003e \u003cp\u003e(kcal/mol)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c4\"\u003e \u003cp\u003eHydrophobic interactions\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c5\"\u003e \u003cp\u003eHydrogen bond\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c6\"\u003e \u003cp\u003eπ-cation\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c7\"\u003e \u003cp\u003eSalt bridge\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003e3s\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colspan=\"2\" nameend=\"c3\" namest=\"c2\"\u003e \u003cp\u003e-7.96\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003ePhe28, Phe126, Phe159, Phe175 Phe195, Val98, Val194, Ala163, Leu248\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003eSer97\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003ePhe28, His247\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003eHis96, His247\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003e4h\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colspan=\"2\" nameend=\"c3\" namest=\"c2\"\u003e \u003cp\u003e-8.05\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003ePhe126, Phe159, Phe175, Phe195, Ala163, Val219, Leu248\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003eSer97\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003ePhe28, His247\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003eHis96, His247\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eGR24\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colspan=\"2\" nameend=\"c3\" namest=\"c2\"\u003e \u003cp\u003e-7.30\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003ePhe28, Phe126, Phe136, Phe159, Phe195, Val98, Val144, Val194\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e\\\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003eHis247\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003eHis247\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e \u003cp\u003eThe docking results are presented in Fig.\u0026nbsp;\u003cspan refid=\"Fig6\" class=\"InternalRef\"\u003e6\u003c/span\u003e and Table\u0026nbsp;\u003cspan refid=\"Tab3\" class=\"InternalRef\"\u003e3\u003c/span\u003e. The binding energy of GR24 docking with AtD14 was \u0026minus;\u0026thinsp;7.3 kcal/mol. The amino acid residue (Phe28, Phe126, Phe136, Phe159, Phe195, Val98, Val144, and Val194) participated in hydrophobic interactions with GR24. His247 formed a π - cation interaction with GR24 while also forming a salt bridge. However, GR24 did not form hydrogen bonds with AtD14 (Fig.\u0026nbsp;\u003cspan refid=\"Fig6\" class=\"InternalRef\"\u003e6\u003c/span\u003eA). The binding modes of compounds \u003cb\u003e3s\u003c/b\u003e and \u003cb\u003e4h\u003c/b\u003e within the active cavity are similar to that of GR24. However, the docking energies of \u003cb\u003e3s\u003c/b\u003e and \u003cb\u003e4h\u003c/b\u003e are significantly lower compared to GR24 (Table\u0026nbsp;\u003cspan refid=\"Tab3\" class=\"InternalRef\"\u003e3\u003c/span\u003e). In addition to forming hydrophobic interactions with the same residues, \u003cb\u003e3s\u003c/b\u003e forms hydrophobic interactions with Val98, Val194, Ala163, and Leu248 residues, while \u003cb\u003e4h\u003c/b\u003e binds to a different set of residues (Phe175, Ala163, Val219, and Leu248). \u003cb\u003e3s\u003c/b\u003e and \u003cb\u003e4h\u003c/b\u003e formed hydrogen bonds with Ser97, established two π-cation interactions with Phe28 and His247, and generated salt bridges with His96 and His247 in the AtD14 binding pocket. Based on the above results, we found that compared with GR24, although there was no significant difference in the number of hydrophobic interactions between \u003cb\u003e3s\u003c/b\u003e and \u003cb\u003e4h\u003c/b\u003e, they all formed hydrogen bonds with Ser97, formed more π - cation interactions with Phe28 and His247, and established more salt bridges with His96 and His247. This explained why \u003cb\u003e3s\u003c/b\u003e and \u003cb\u003e4h\u003c/b\u003e bound to AtD14 at lower binding energy and exhibited better biological assay.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003ePlants continuously adjust their ABA content in response to physiological and environmental changes. ABA-glucosyl ester is the primary product resulting from ABA inactivation through binding with glucose and exhibits considerable stability. As the ABA content in plants decreases, ABA glucosyl ester gradually accumulates within plants, thereby facilitating plant growth and development\u003csup\u003e[\u003cspan citationid=\"CR35\" class=\"CitationRef\"\u003e35\u003c/span\u003e]\u003c/sup\u003e. Therefore, we hypothesize that the mechanism of action of estrogen mimetics involves binding reactions with Phe, His, and Ser residues in estrogen receptor proteins, then promoting the inactivation of abscisic acid and glucose binding in plants to accumulate ABA glucose esters, enhancing the synthesis of auxin, cytokinin, and gibberellin in plants, and ultimately regulating plant growth and development\u003csup\u003e[\u003cspan additionalcitationids=\"CR37 CR38\" citationid=\"CR36\" class=\"CitationRef\"\u003e36\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR39\" class=\"CitationRef\"\u003e39\u003c/span\u003e]\u003c/sup\u003e.\u003c/p\u003e"},{"header":"Conclusions","content":"\u003cp\u003eIn this study, strigolactone mimics were efficiently synthesized in three steps from methylmalonic acid, glyoxal and phenols/phenylthiophenols. The synthesized SL mimics showed significant growth-promoting activity for plants containing SL receptor proteins. In the subsequent phytohormone response analysis, the target compounds reduce the ABA content in plants by regulating the binding of ABA and glucose, and a large amount of ABA glucosyl ester accumulates. Then, the synthesis of auxin, cytokinin, and gibberellin is promoted to regulate plant growth and development. The ligand docking study showed that SL mimics may generate subsequent plant hormone responses by binding to amino acids (such as Phe, Val, Ser, and His) in SL receptor proteins within plants. This study provides significance for designing new strigolactone mimics as plant growth regulators.\u003c/p\u003e"},{"header":"Abbreviations","content":"\u003cp\u003eSLs\u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp;Strigolactones\u003c/p\u003e\n\u003cp\u003eABA \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp;\u0026nbsp;Abscisic acid\u003c/p\u003e\n\u003cp\u003eCTK\u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp;Cytokinin\u003c/p\u003e\n\u003cp\u003eGA\u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp;Gibberellin\u003c/p\u003e\n\u003cp\u003eNMR\u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp;\u0026nbsp;Nuclear magnetic resonance\u003c/p\u003e\n\u003cp\u003eTMS \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp;\u0026nbsp;Tetramethylsilane\u003c/p\u003e\n\u003cp\u003eDMSO-d6\u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp;\u0026nbsp;Dimethyl sulfoxide\u003c/p\u003e\n\u003cp\u003eCDCl3\u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp;Deuterated chloroform\u003c/p\u003e\n\u003cp\u003eHR-MS\u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp;\u0026nbsp;High-resolution mass spectrometry\u003c/p\u003e\n\u003cp\u003eHPLC\u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp;High-performance liquid chromatography\u003c/p\u003e\n\u003cp\u003eACN\u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp;\u0026nbsp;Acetonitrile\u003c/p\u003e\n\u003cp\u003eMeOH\u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp;\u0026nbsp;Methanol\u003c/p\u003e\n\u003cp\u003eH2SO4\u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp;Sulfuric acid\u003c/p\u003e\n\u003cp\u003eNaCl\u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp;\u0026nbsp;Sodium chloride\u003c/p\u003e\n\u003cp\u003eEtOAc\u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp;\u0026nbsp;Ethyl acetate\u003c/p\u003e\n\u003cp\u003eNa\u003csub\u003e2\u003c/sub\u003eSO\u003csub\u003e4\u003c/sub\u003e\u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp;Sodium sulfate\u003c/p\u003e\n\u003cp\u003eSOCl\u003csub\u003e2\u003c/sub\u003e\u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; Thionyl chloride\u003c/p\u003e\n\u003cp\u003eDMF\u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp;\u0026nbsp;N, N-dimethylformamide\u003c/p\u003e\n\u003cp\u003eCH\u003csub\u003e2\u003c/sub\u003eCl\u003csub\u003e2\u003c/sub\u003e\u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp;Dichloromethane\u003c/p\u003e\n\u003cp\u003eNaHCO\u003csub\u003e3\u003c/sub\u003e\u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp;\u0026nbsp;Sodium bicarbonate\u003c/p\u003e\n\u003cp\u003eMgSO\u003csub\u003e4\u003c/sub\u003e\u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp;Magnesium sulfate\u003c/p\u003e\n\u003cp\u003eLC-MS/MS \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp;Liquid chromatography-tandem mass spectrometry\u003c/p\u003e\n\u003cp\u003eLIT \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp;\u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp;Linear ion trap\u003c/p\u003e\n\u003cp\u003eQQQ\u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp;\u0026nbsp;Triple quadrupole\u003c/p\u003e\n\u003cp\u003eQTRAP\u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp;\u0026nbsp;Triple quadrupole-linear ion trap mass spectrometer\u003c/p\u003e\n\u003cp\u003eCUR\u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp;Curtain gas\u003c/p\u003e\n\u003cp\u003eMRM\u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp;Multiple reaction monitoring\u003c/p\u003e\n\u003cp\u003eDP\u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp;\u0026nbsp;Declustering potential\u003c/p\u003e\n\u003cp\u003eCE\u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp;\u0026nbsp;Collision energies\u003c/p\u003e\n\u003cp\u003eSer \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp;\u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp;Serine\u003c/p\u003e\n\u003cp\u003eHis\u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp;Histidine\u003c/p\u003e\n\u003cp\u003eAsp\u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp;\u0026nbsp;Aspartic acid\u003c/p\u003e\n\u003cp\u003eLGA\u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp;Lamarckian genetic algorithm\u003c/p\u003e\n\u003cp\u003ePhe\u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp;Phenylalanine\u003c/p\u003e\n\u003cp\u003eVal\u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp;Valine\u003c/p\u003e\n\u003cp\u003eAla\u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp;Alanine\u003c/p\u003e\n\u003cp\u003eLeu \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp;Leucine\u003c/p\u003e"},{"header":"Declarations","content":"\u003cp\u003eSUPPORTING INFORMATION\u0026nbsp;\u003c/p\u003e\n\u003cp\u003e\u003csup\u003e1\u003c/sup\u003eH NMR, \u003csup\u003e13\u003c/sup\u003eC NMR, and HRMS spectra for the target compounds, Promotion germination activity、Corn Dose effect、Corn Plant growth promotion rate. \u0026nbsp;\u003c/p\u003e\n\u003cp\u003eEthical approval and consent to participate\u003c/p\u003e\n\u003cp\u003eNot applicable\u003c/p\u003e\n\u003cp\u003eConsent for publication\u003c/p\u003e\n\u003cp\u003eNot applicable\u003c/p\u003e\n\u003cp\u003eAvailability of data and materials\u003c/p\u003e\n\u003cp\u003eThe data sets used and/or analyzed during the current study are available from the corresponding author on reasonable request.\u003c/p\u003e\n\u003cp\u003eCompeting interests\u003c/p\u003e\n\u003cp\u003eThe authors declare no competing financial interest.\u003c/p\u003e\n\u003cp\u003eFunding\u003c/p\u003e\n\u003cp\u003eThe authors acknowledge National Natural Science Foundation of China (31901906), Natural Science Research Project of Anhui Educational Committee (2023AH040141), Anhui Provincial Natural Science Foundation (2308085MC93), and the USDA Hatch grant (HAW05020H).\u003c/p\u003e\n\u003cp\u003eAuthors\u0026rsquo; contributions\u003c/p\u003e\n\u003cp\u003eLinfeng Kai: Investigation, data analysis, Writing\u0026ndash;review \u0026amp; editing Writing \u0026ndash; original draft. Chao Qin: Investigation, data analysis. Hongfei He: Validation, data analysis. Qing X Li: Writing \u0026ndash; review \u0026amp; editing and data interpretation. Rimao Hua: Project administration, Supervision. Pei Lv: Writing \u0026ndash; review \u0026amp; editing.\u0026nbsp;Project administration, Methodology, Validation, Supervision, Resources.All authors read and approved of the final manuscript.\u003c/p\u003e\n\u003cp\u003eAcknowledgments\u003c/p\u003e\n\u003cp\u003eNot applicable\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\u003cli\u003e\u003cspan\u003eKgosi R L, Zwanenbugr B, Mwakaboko A S, et al. Strigolactone analogues induce suicidal seed germination of Striga spp. in soil. Weed Res. 2012; 52(3): 197\u0026ndash;203.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eMohamed, K, I, et al. The genus Striga (Scrophulariaceae) in Afric. 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J Plant Res. 2011; 124(4): 489\u0026ndash;99.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eHagen G, Guilfoyle T J, Gray W M. Auxin Signal Transduction. Essays Biochem, 2015, 58(1): 282\u0026ndash;307.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eRomanov G A. The discovery of cytokinin receptors and biosynthesis of cytokinins: A true story. Russ J Plant Physiol. 2011; 58(4): 743\u0026ndash;7.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eRizza A, Jones A M. The makings of a gradient: spatiotemporal distribution of gibberellins in plant development. Curr Opin Plant Biol. 2019; 47(1): 9\u0026ndash;15.\u003c/span\u003e\u003c/li\u003e\u003c/ol\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"hideJournal":true,"highlight":"","institution":"","isAcceptedByJournal":false,"isAuthorSuppliedPdf":false,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"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":"strigolactone, corn, germination, growth, hormone","lastPublishedDoi":"10.21203/rs.3.rs-6667656/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-6667656/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003ch2\u003eBackground\u003c/h2\u003e \u003cp\u003ePhytohormones regulate plant growth, development, and stress responses. Strigolactones, a class of phytohormones, have attracted significant scientific interest due to their multifunctional roles in plant biology and ecological interactions.\u003c/p\u003e\u003ch2\u003eResults\u003c/h2\u003e \u003cp\u003eIn this study,35 strigolactone mimics were efficiently synthesized via substitution reaction of pre-synthesized 5-chloro-3-methylfuran-2(5\u003cem\u003eH\u003c/em\u003e)-one with phenolics and benzenethiols. Most of the chemicals showed seed germination promoting activities on corn, sorghum, soybean, and sunflower seed. At a concentration of 100 mg/L, \u003cb\u003e3s\u003c/b\u003e and \u003cb\u003e4h\u003c/b\u003e showed 56% and 63% promoting rate of corn bud growth, while 50% and 62% promoting rate of sorghum root growth. The promoting rates of \u003cb\u003e3s\u003c/b\u003e and \u003cb\u003e4h\u003c/b\u003e on corn, sorghum, soybean and sunflower root growth ranged to 35\u0026ndash;48% and 46\u0026ndash;71%. The promotion effect of the target compound exhibited dose effect, increasing within the range of 0.01-10 mg/L and decreasing within the range of 10\u0026ndash;100 mg/L. The optimal promotion rates for maize root and shoot growth at \u003cb\u003e3s\u003c/b\u003e and \u003cb\u003e4h\u003c/b\u003e were achieved at a concentration of 10 mg/L. \u003cb\u003e3s\u003c/b\u003e and \u003cb\u003e4h\u003c/b\u003e regulated the content of the abscisic acid, auxin, cytokinin and gibberellin content to promote plant germination. The binding energy of GR24 docking with strigolactone receptor proteins derived from \u003cem\u003eArabidopsis\u003c/em\u003e (AtD14) was \u0026minus;\u0026thinsp;7.30 kcal/mol, while \u003cb\u003e3s\u003c/b\u003e and \u003cb\u003e4h\u003c/b\u003e were \u0026minus;\u0026thinsp;7.96 and \u0026minus;\u0026thinsp;8.05 kcal/mol.\u003c/p\u003e\u003ch2\u003eConclusions\u003c/h2\u003e \u003cp\u003eThe structure-activity relationships of 35 novel strigolactone mimics and docking simulations provided structural optimization strategies for designing new strigolactone mimics as plant growth regulators.\u003c/p\u003e","manuscriptTitle":"Synthesis and Germination Activity of 5-(thio)phenol-3-methylfuran-2(5H)-one Analogues as Strigolactone Mimics","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2025-05-23 18:32:07","doi":"10.21203/rs.3.rs-6667656/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":"8454257f-abb7-40d9-947e-5439bb212de4","owner":[],"postedDate":"May 23rd, 2025","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"posted","subjectAreas":[],"tags":[],"updatedAt":"2025-06-09T15:53:49+00:00","versionOfRecord":[],"versionCreatedAt":"2025-05-23 18:32:07","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-6667656","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-6667656","identity":"rs-6667656","version":["v1"]},"buildId":"8U1c8b4HqxoKbykW_rLl7","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}