Allelic Diversity of OsGW5.1 Regulating Grain Width in Rice

Rice is the staple food for more than half of the global population and rice production has to be increased by at least 50% during 2030 to meet the requirements of the rapidly increasing population. Rice yield is determined by several quantitative traits viz. number of productive tillers, panicle length, number of grains per panicle, grain size, and photosynthetic efficiency. Grain size is a major determinant of rice yield and it is primarily governed by grain length, grain width, and grain thickness. Several candidate genes modulating yield components have been discovered and put into breeding applications. OsGW5.1 (LOC_Os05g25350), encoding for a receptor-like kinase is reported to alter grain width in rice. Advancements in genomics and re-sequencing of 3000 rice genotypes paved way for measuring allelic diversity of putative candidate genes, identification of elite haplotypes, and developing functional markers for breeding applications. In this study, the allelic diversity of OsGW5.1 was analyzed in a set of 151 IRRI-3K panel lines. Eight non-synonymous SNPs were observed and haplotype analysis identified four haplogroups of OsGW5.1. Differences in grain width of the different haplogroups were tested by Dunnet's test. Results revealed that haplotype 1 (H1) and haplotype 2 (H2) showed a significant difference in grain width. KIKUBA (haplogroup 1) was found to possess greater grain width (3.62 mm) whereas NS1515 (haplotype 2) possessed a slender grain type (1.88 mm). Identified superior donors possessing elite haplotypes of GW5.1 may be utilized in haplotype based breeding to develop next generation tailor-made high yielding rice varieties with desired grain size.