Genome-Wide Association Mapping For Grain Shape In Rice Accessions

Grain shape is a very important goal in the rice breeding program nowadays. Underlying the genetic basis of grain shape would largely speed the breeding process. In the present study, a diverse panel of 1016 rice accessions from 70 countries and areas worldwide were evaluated for their grain shapes. There were large variations for all three grain shape traits, including grain length, grain width and length to width ratio, and they had significantly positive or negative correlations with each other. Besides, high positive correlations were found between two experimental years. Genome-wide association mapping strategy was conducted to identify QTL for grain shape using 509219 high quality SNP genotypes and grain shape traits. A total of 70 QTL were identified in all chromosomes. Among them, 16 QTL were found on chromosome 1, 2, 3, 5, 7, 9 and 11 expressed in both years. Eight genomic regions on chromosome 1, 3, 4, 5, 7 and 9 had pleiotropic effects on two or three traits. Four genomic regions on chromosome 3, 5, 6 and 7 were identified in both year and controlled more than two traits. Besides, 25 QTL on all chromosomes except chromosome 8, 10 and 12 had large effect on the traits. In conclusion, these results helped us better understand the genetic basis of rice grain shape and provide valuable gene resources for improving rice grain for desired shape. (C) 2020 Friends Science Publishers