Mapping And Validation Of QTL For Grain Size,Grain Weight And Stigma Exsertion In Rice

Rice grain size(grain length,grain width,length-to-width ratio,grain thickness)is one of the factors determining the grain weight,which further determines rice yield.Grain size not only affects the appearance quality and eating quality,but also influences the market value of grain and the consumer tendency.The stigma exsertion in rice affects the yield of hybrid seed on male sterile lines.The study of grain size,grain weight and stigma exsertion of rice is of great significance to the genetic improvement and breeding of rice.In this study,the F2 population,F3 population and BC1F2 population derived from Guangzhan 63-4S and Dodda were used to detect and validate QTL for rice grain size,1000-grain weight and stigma exsertion.1.A Q TL analysis was performed with the F2 population(2014)and F3 population(2015)using SSR markers.Thirteen QTL controlling grain length were detected,which were located on chromosomes 1,3,4,5,6 and 8,respectively,and accounted for the phenotypic variance ranging from 0.03% to 25.39%.Seven QTL controlling grain width were detected,which were distributed on chromosomes 2,4,8,11 and 12,respectively,and the phenotypic variance explained ranged from 4.58% to 13.97%.N ine Q TL controlling grain length-to-width ratio were detected,which were located on chromosomes 1,2,3,7,8,9,11 and 12,respectively,and the range of phenotypic variance explained was from 1.46% to 10.00%.Ten Q TL controlling grain thickness were detected,and distributed on chromosomes 2,3,4,7 and 11,respectively,with the phenotypic variance ranging from 0.17% to 20.98%.Eleven QTL controlling 1000-grain weight were detected,and located on chromosomes 1,2,3,4,6,7 and 11,respectively,and the range of the phenotypic variance was from 0.83% to 20.68%.2.A QTL analysis was conducted with the F2 population(2014)and F3 populations(2015 and 2016)using SNP markers from the Rice6 K chip.Eighteen QTL controlling grain length were detected,which were located on chromosomes 1,3,4,5,6,9 and 11,respectively,and the phenotypic variance ranged from 0.29% to 24.96%.Eleven QTL controlling grain width were identified,which were located on chromosomes 1,2,4,5,6,8,9 and 11,respectively,and the range of the phenotypic variance was from 0.06% to 20.66%.Twenty-three QTL controlling grain length-to-width ratio were detected,and distributed on chromosomes 2,3,4,5,6,8,9,11 and 12,respectively,with the phenotypic variation explained ranging from 0.06% to 17.80 %.Twenty Q TL for grain thickness,were located on chromosomes 1,2,3,4,6,7,8,9 and 11 chromosomes,respectively,and the phenotypic variation was in the range of 0.05%-26.64%.Twelve QTL controlling 1000-grain weight,which were located on chromosomes 1,2,3,5,6,7 and 11,respectively,and accounted for the phenotypic variance ranging from 0.04% to 18.47%.3.A QTL analysis was conducted with the F3 populations(2016)using SNP markers from the RICE6 K chip.Twenty Q TL controlling stigma exsertion were detected,including eleven QTL controlling single stigma exsertion,which were located on chromosomes 2,5,6 and 9,respectively,and the phenotypic variance ranged from 0.14% to 52.82%.Nine QTL controlling dual stigma exsertion were identified,which were located on chromosomes 5,6,9 and 11,respectively,and the range of the phenotypic variance was from 0.51% to 31.59%.4.In order to confirm the genetic effect of QTL controlling grain size,1000-grain weight and stigma exsertion,A BC1F2 population was developed under the background of Guangzhan 63-4S using MAS.Eight QTL controlling grain size and 1000-grain weight from the SSR analysis were validated,and the phenotypic variation was in the range of 0.09% to 19.55%.Eleven QTL controlling grain size and 1000-grain weight from the SNP analysis were confirmed,and the phenotypic variation was in the range of 2.29% to 19.55%.Two Q TL controlling single stigma exsertion were detected by SNP analysis,and the phenotypic variation was 6.68% and 12.77%,respectively..