Genome-wide association study (GWAS) of seed germination-related traits in rice and identification of candidate genes

Abstract Background Genome-wide association study (GWAS) has become an accepted and powerful method for understanding the associations between phenotypes and genotypes. In agricultural production, uniform and rapid germination is an important prerequisite in crop production. Here, a rice (Oryza sativa L.) GWAS with 33,934 SNPs (MAF > 0.05) for eight germination traits including germination percentage (GP), shoot (SL) and root length (RL), root (RFW) and shoot fresh weight (SFW), root (RDW) and shoot (SDW) dry weight, and number of days to germinate (NDG) was performed to define genomic regions influencing seed germination. Results Loci (43) with 70 significant germination-associated markers were detected across all rice chromosomes. Some of novel candidate associated genes were: LOC_Os01g26210 (OsWAK6) co-located with qGR-1 that is seed vigor QTL, LOC_Os07g23944 (GH31) with an α-glucosidases /starch lyase activity; id7000519 marker that corresponds to a gene cluster containing glutathione S-transferase and glucan endo-1,3-β-glucosidase co-located with qAG3 germination-related marker, LOC_Os06g47640 (calmodulin-related calcium sensor protein 29) involved in the inhibition of ABA during seed germination, and id4006430 marker that corresponds to a gene cluster containing three GH17 hydrolytic enzyme that are co-located with qHD4 and qGI1 markers. Conclusion The germination process is an initial and important step in the production of agricultural products, especially for rice, which is a crop plant that is grown in flooded lands. Here, the genetic diversity of rice genotypes was put under scrutiny for germination. Our GWAS results identified several likely candidate genes for germination traits that will greatly contribute to our understanding of the genetic complexity underlying the corresponding traits. The associated genes with the germination traits can be generally classified as hydrolytic enzymes and regulatory proteins that can directly or indirectly influence germination.