Fine Mapping Of Novel QTLs And Prediction Of Candidate Genes For Grain Weight In Wheat

Wheat is an important food crop in the world,and the increase in yield is important to ensuring food security.In this study,a recombinant inbred line(RIL,227 lines)population derived from the cross of YXM×Zhongyou9507 were used for mapping QTLs related to thousand-grain weight,grain length and grain width using SSR markers,Wheat 660 K SNP chips and phenotypic data.Wheat 55 K SNP chip technology was use to construct high density genetic linkage map for fine-mapping the major QTL,and candidate genes was predicted based on bioinformatics analysis.1.Using SSR markers,24 QTLs for yield were detected on 10 chromosomes,and the phenotypic variations explained ranged from 2.8%to 20.21%,including 11 QTLs for thousand grain weight,8 QTLs for grain length,and 3 QTLs for grain width.Particularly,the major QTLs related to thousand grain weight and grain length were detected on chromosome 2A(gwm95-gwm515,123.21-158.80Mb),explaining 8.56-12.84%and 8.4～10.8%of the phenotypic variations,respectively.The major QTLs for grain weight and grain width were detected on chromosome 3B(cfd79-barc203),explaining 12.00～16.61%and 9.57～16.04%of the phenotypic variations,respectively.The main QTL for grain weight was detected on chromosome 7A(wmc83-gwm60,54.96-89.97Mb),explaining 7.44～8.81%of the phenotypic variations,and QTLs related to grain length was detected within barc49-barc29,explaining 8.73%～11.48%of the phenotypic variations.2.Combined with the 660K SNP chip information,CAPS markers were developed,the major QTLs for thousand grain weight and grain length were narrowed in the region ZY-2A-98～ZY-2A-31(133.70-155.58Mb).The major QTL for grain width was narrowed within the interval ZY-2A-31～ZY-2A-21(141.28-155.58Mb),explaining 11.85～13.96%of the phenotypic variations.The QTLs related to grain weight and grain length were located within the CAPS marker interval ZY10～barc102(16.89-17.57Mb),explaining 13.77-24.27%and 6.42-22.35%of the phenotypic variations,respectively.3.Using Wheat 55 K SNP chip technology,the high density linkage map was constructed,which consists of 2373 polymorphic SNPs,spaning 432.02 cM with.Seven QTLs for thousand grain weight were detected on chromosomes 1 A,2A,2B,3A,3B,3D,5A and 7D,explaining 5.01-20.34%of the phenotypic variations.Four QTLs for grain length were detected on chromosomes 1A,2A,6B and 7B,explaining 5.33～11.49%of the phenotypic variations.Six QTLs for grain width were detected on chromosomes 3A,3D,4D,5A and 7A,explaining 7.37-11.3%of the phenotypic variations.4.Finally,QTLs for thousand grain weight,grain width and grain length on chromosome 2A were finely narrowed ZY-2A-21～ZY-2A-31(141.28-155.58Mb),explaining 10.42-32.41%,5.6-10.3%and 7.02%of the phenotypic variations,respectively.Also,QTLs for thousand grain weight and grain width on chromosome 3B were finely mapped ZY10-ZY17(16.89-18.49Mb),explaining 6.32-9.74%and 5.53-11.86%of the phenotypic variations,respectively.5.Twenty candidate genes were predicted within the interval ZY10-ZY17 on chromosome 3B,including six yield-related genes:genes TraesCS3B01 G035200,TraesCS3B01G035400,TraesCS3B01G035500 encode Ubiquitin,and TraesCS3B01G041900LC.Genes TraesCS3B01G035100 and TraesCS3B01G041800LC encode for F-box/rni-like superfamily proteins(F-box/rni-like superfamily proteins),both of which are involved in the ubiquitin proteasome pathway and are likely to be involved in the formation of grain weight as candidate genes.