小麦茎秆水溶性碳水化合物含量主效QTLQWSC.caas-7DS精细定位OA

Stem-reserved water-soluble carbohydrates(WSC)serve as a crucial carbon source for grain filling in wheat(Triticum aestivum).Enhancing stem WSC content is a key strategy for achieving high and stable grain yield.The major-effect QTL QWSC.caas-7DS,which regulates stem WSC content at 10 d after flowering(WSC10),was previously identified in the'Yangmai 16'(YM16)/'Zhongmai 895'(ZM895)doubled haploid(DH)population,with physical interval of 11.7 Mb.To fine-map this QTL,identify the candidate genes,and develop molecular markers,a cross XY015/XY102 was made with 2 DH lines XY015 and XY102 that contrast in genotype at QWSC.caas-7DS but shared identical genotypes at other known WSC loci.Subsequently,F2,F2:3,and F2:4 segregating populations were constructed.Based on whole-genome resequencing data of YM16 and ZM895,20 kompetitive allele-specific PCR(KASP)markers were successfully developed within the target interval,and a high-density genetic map was constructed using 755 F2 individuals.The homozygous F2:4 lines derived from 35 recombinant F2 plants were used for phenotyping of WSC10 in 3 environments;in combination with the genotypic data of these lines,QWSC.caas-7DS was finely mapped to the 66.44～69.14 Mb interval on chromosome 7DS.Comprehensive analysis of genomic resequencing data of YM16 and ZM895,along with annotations and expression profiles of the genes in the QTL interval,6 genes were preliminarily presumed as the candidate genes for QWSC.caas-7DS.According to the gene expression profile database,Vrn-D3(gene ID:TraesCS7D01G111600),one of the candidate genes,showed high expression levels in stem and leaf tissues,and it may regulate stem WSC and thousand-kernel weight(TKW)by modulating carbon balance between source and sink tissues.Vrn-D3 was cloned from YM16 and ZM895,and a G base"insertion/deletion"variation located in the third exon was identified.A molecular marker,Vrn-D3M,was developed for genotyping this variation and was validated in 157 wheat varieties from the Yellow and Huai Valleys Winter Wheat Zone.The results indicated that Vrn-D3M could be effectively used for molecular breeding targeting for improvement of WSC10 and TKW.The findings of this study lay a solid foundation for the final cloning and functional study of QWSC.caas-7DS,and also provide an efficient molecular tool for breeding applications.