普通小麦旗叶大小QTL定位与候选基因分析OA

[Objective]Flag leaf size is a critical component of wheat plant architecture,playing a vital role in photosynthesis,yield formation,and stress response.The identification of major quantitative trait loci(QTL)and candidate genes regulating flag leaf size-related traits will provide theoretical support and genetic resources for the molecular design breeding of high-yielding wheat ideotypes.[Method]A recombinant inbred line(RIL)population comprising 184 lines was derived from a cross between the Chinese elite cultivar Bainong 4199(BN4199,female parent)and the exotic variety Zhengyinmai 2(ZYM2,male parent).Genotyping of the BN4199/ZYM2-RIL population was performed using the wheat 120K liquid chip(120K-4HWA)to construct a high-density genetic linkage map.Based on the composite interval mapping(CIM)method,QTL mapping was performed to identify stable major-effect loci and to analyze their additive effects using the flag leaf size-related traits,including flag leaf length(FLL),flag leaf width(FLW),flag leaf length/width ratio(FLR),and flag leaf area(FLA),and the best linear unbiased estimate(BLUE)values obtained across four environments(two locations over two years).Furthermore,candidate gene annotation and identification,as well as tissue expression pattern analysis,were conducted using several wheat functional genomics databases.In addition,corresponding kompetitive allele-specific PCR markers(KASP)were developed based on polymorphic SNP sites located within the stable QTL intervals.[Result]A high-density genetic linkage map of the BN4199/ZYM2-RIL population was constructed,comprising 27 linkage groups with 3 666 SNP markers,covering all 21 wheat chromosomes.The map spanned 5 194.09 cM with an average inter-marker distance of 1.42 cM.High collinearity with the Chinese Spring physical map indicated the robustness of this genetic map.A total of 130 QTL were detected,including:31 for FLL,34 for FLW,33 for FLR,and 32 for FLA,distributed across all chromosomes except 3B,3D,and 4D.Among these,20 loci on chromosomes 1A,2A,2B,2D,4B,5A,7A,and 7B were environmentally stable QTL,with 10 being novel loci reported for the first time.A total of 3 923 genes were annotated within the 20 stable QTL intervals.Gene Ontology(GO)analysis revealed significant enrichment in transcription elongation factor complex,UDP-glycosyltransferase activity,rhythmic processes,and chromatin-mediated maintenance of transcription.Based on gene function annotation,information from the cloning and characterization of rice orthologs,and analysis via the QTG-miner module of an interactive wheat functional gene discovery platform,55 candidate genes were prioritized within stable QTL intervals,exhibiting different expression patterns at various developmental stages of wheat root,stem,leaf,spike and grain tissues.In addition,10 KASP markers closely linked to the novel QTL were developed.[Conclusion]A high-density genetic linkage map was constructed using the wheat 120K liquid chip,and 20 stable major QTL controlling flag leaf size-related traits were detected,10 of which were novel loci.The KASP molecular markers closely linked to novel QTL were developed,and 55 potential candidate genes were identified in this study.