小麦科大116×科大101 F_(2)群体穗长主效QTL定位及候选基因预测

Major QTL Mapping and Candidate Gene Prediction of Spike Length in F_(2)Population of Wheat Keda 116×Keda 101

穗长是小麦重要的农艺性状,与产量构成因素密切相关。旨在研究小麦穗长遗传基因,筛选与穗长基因连锁的分子标记,为小麦分子标记辅助育种提供分子支撑。以科大116和科大101为亲本构建的F_(2)群体为试验材料,通过SSR分子标记,构建覆盖小麦基因组的遗传图谱,并结合完备复合区间作图法对穗长进行QTL定位。采用3234对引物,共筛选出434对在双亲间具有多态性的引物,多态性引物的检出率为13.42%。通过BSA混池分析,共筛选出28个可能与穗长连锁的分子标记,其中16个标记通过262株群体验证与目标基因紧密连锁。通过QTL-IciMapping软件构建小麦染色体组的遗传图谱,标记间的平均遗传距离为38.66 cM,共检测出7个与穗长相关的QTL位点,分别位于3B、4A、4B和6B染色体上,其加性效应值均为正值,对表型性状遗传变异的贡献率在4.01%~23.16%。在4B染色体上定位出2个主效QTL位点,贡献率为17.59%~23.16%。其中,Qsl4B-2距离其最近的分子标记只有3.5 cM,为连锁最紧密的一个QTL位点,分析发现其可能为新的主效QTL位点。因此,4B染色体上可能存在与穗长相关的基因。通过分析预测,在4B染色体的yzu397456~yzu404917和yzu409422~yzu405167标记区间内,可能存在7个调控小麦穗长的候选基因,在穗中持续高表达。

Spike length is an important agronomic trait in wheat and is closely related to yield components.Studying wheat spike length genes and screening molecular markers linked to spike length genes can provide molecular support for wheat molecular marker-assisted breeding.The F_(2)population constructed with Keda 116 and Keda 101 as parents was used as test material to construct a genetic map covering the wheat genome by SSR molecular markers and to locate QTLs for spike length by combining the complete composite interval mapping method.A total of 434 pairs of primers with polymorphism between parents were screened from 3234 pairs of primers,and the detection rate of polymorphic primers was 13.42%.A total of 28 molecular markers were screened for possible linkage to spike length by BSA mixed pool analysis,16 of these markers were verified to be tightly linked to the target gene by a population of 262 plants.The genetic map of wheat chromosome group was constructed by QTL-IciMapping software,and the average genetic distance between markers was 38.66 cM.A total of seven QTLs loci associated with spike length were detected,which were located on chromosomes 3B,4A,4B and 6B.The additive effect values of all the seven QTLs were positive and their contributions to the genetic variation of phenotypic traits ranged from 4.01%to 23.16%.Two major QTLs were mapped on chromosome 4B,explaining 17.59%-23.16%of the phenotypic variance.Among them,Qsl4B-2 was the most closely linked QTL locus with only 3.5 cM away from the nearest molecular marker,and the analysis found that it might be a new major QTL locus.Therefore,genes associated with spike length might exist on chromosome 4B.Within the marker interval of chromosome 4B from yzu397456 to yzu404917 and yzu409422 to yzu405167,there might be seven candidate genes regulating wheat spike length,which were consistently highly expressed in the spike.