Study On Genetic Interaction And Breeding Application Of Rice GS9 Gene With Other Grain Shape Genes

Grain shape plays an important role in the formation of rice yield.Grain shape also affects rice quality,especially processing and appearance quality.In this study,to explore the breeding value of gs9 gene,it was introduced into different rice varieties.And the polymerization effect analysis of GS9 and other grain size genes,GS3,GW5 and GW7 was conducted.NIL(gs9),NIL(gs3),NIL(GW5)and NIL(GW7)with the same genetic 'background were used for hybridizing NIL(gs3),NIL(GW5),NIL(GW7)and NIL(gs9),respectively,and thus obtaining polymerization lines NIL(gs9/gs3),NIL(gs9/GW5),NIL(gs9/GW7).gs9 causes more slender grains,gs3 causes bigger grains,GW5 causes narrower grains,and GW7 causes more slender grains.gs9 combined with the other three grain size genes could produce a more obvious effect than single gene.However,the interaction effect of GS9 and GS3 was further verified through the CRISPR/Cas9 system,which exhibit a similar effect with NIL(gs9/gs3).At transcriptional level,GS3,GW5 and GW7 mutations did not affect the expression of GS9 gene.And GS9 mutation did not affect the expression of GS3 and GW7 genes.Therefore,GS9 regulating grain formation may be independent of GS3,GW5,GW7 genes.Mining allelic variation of GS9 in numerous rice germplasms,we found that wild-type GS9 gene may have the same grain shape,and only loss of function gs9 gene could improve grain shape.However,no loss-of-function gs9 allele was found in natural varieties.Introducing gs9 allele into high yield varieties to evaluate the breeding value of gs9,which revealed that gs9 containing plants show more slender grains than non-containing plants in the same genetic background.Therefore,GS9 can improve the rice appearance quality.These results supplied a well foundation for breeding application of GS9.