Mapping of QTL for total spikelet number per spike on chromosome 2D in wheat using a high-density genetic map

Abstract Total spikelet number per spike (TSS) is one of the key components of grain yield in wheat. Chromosome (chr.) 2D contains numerous genes that control TSS. In this study, we evaluated 138 F8 recombinant inbred lines (RILs) derived from an F2 population of a synthetic hexaploid wheat line (SHW-L1) and a common wheat cultivar (Chuanmai 32) for TSS in six different environments. To identify quantitative trait loci (QTL) for TSS, we constructed an integrated high-density genetic map of chr. 2D containing two simple sequence repeats, 35 diversity array technology markers, and 143 single nucleotide polymorphisms. We identified three stable QTL for TSS that individually explained 9.7–19.2% of the phenotypic variation and predicted 23 putative candidate genes within the QTL mapping interval. Overall, our results provide insight into the genetic basis of TSS in synthetic hexaploid wheat that may be useful in breeding high-yielding wheat cultivars.

摘要 每穗小穗总数（Total spikelet number per spike, TSS）是小麦籽粒产量的关键构成要素之一。2D染色体（chromosome 2D, chr. 2D）携带有众多调控每穗小穗总数的基因。本研究针对由人工合成六倍体小麦品系（synthetic hexaploid wheat line, SHW-L1）与普通小麦品种川麦32（Chuanmai 32）的F₂群体衍生而来的138个F₈代重组自交系（recombinant inbred lines, RILs），在6种不同环境下开展每穗小穗总数的表型鉴定。为挖掘调控每穗小穗总数的数量性状位点（quantitative trait loci, QTL），本研究构建了包含2个简单序列重复（simple sequence repeats, SSRs）、35个多样性阵列技术（diversity array technology, DArT）标记以及143个单核苷酸多态性（single nucleotide polymorphisms, SNPs）的2D染色体整合高密度遗传图谱。最终鉴定到3个稳定的每穗小穗总数QTL，单个QTL可解释9.7%~19.2%的表型变异，并在QTL定位区间内预测得到23个潜在候选基因。综上，本研究结果阐明了人工合成六倍体小麦每穗小穗总数的遗传基础，可为高产小麦品种选育提供理论参考。