Table_5_The 55K SNP-Based Exploration of QTLs for Spikelet Number Per Spike in a Tetraploid Wheat (Triticum turgidum L.) Population: Chinese Landrace “Ailanmai” × Wild Emmer.XLSX

Spikelet number per spike (SNS) is the primary factor that determines wheat yield. Common wheat breeding reduces the genetic diversity among elite germplasm resources, leading to a detrimental effect on future wheat production. It is, therefore, necessary to explore new genetic resources for SNS to increase wheat yield. A tetraploid landrace “Ailanmai” × wild emmer wheat recombinant inbred line (RIL) population was used to construct a genetic map using a wheat 55K single- nucleotide polymorphism (SNP) array. The linkage map containing 1,150 bin markers with a total genetic distance of 2,411.8 cm was obtained. Based on the phenotypic data from the eight environments and best linear unbiased prediction (BLUP) values, five quantitative trait loci (QTLs) for SNS were identified, explaining 6.71–29.40% of the phenotypic variation. Two of them, QSns.sau-AM-2B.2 and QSns.sau-AM-3B.2, were detected as a major and novel QTL. Their effects were further validated in two additional F2 populations using tightly linked kompetitive allele-specific PCR (KASP) markers. Potential candidate genes within the physical intervals of the corresponding QTLs were predicted to participate in inflorescence development and spikelet formation. Genetic associations between SNS and other agronomic traits were also detected and analyzed. This study demonstrates the feasibility of the wheat 55K SNP array developed for common wheat in the genetic mapping of tetraploid population and shows the potential application of wheat-related species in wheat improvement programs.

每穗小穗数（SNS）是决定小麦产量的首要因素。普通小麦育种会降低优质种质资源的遗传多样性，从而对未来的小麦生产产生不利影响。因此，有必要探索新的SNS遗传资源以提升小麦产量。本研究采用四倍体地方品种“Ailanmai”与野生黑麦小麦重组自交系（RIL）群体，利用小麦55K单核苷酸多态性（SNP）芯片构建遗传图谱。获得的连锁图谱包含1,150个 bins 标记，总遗传距离为2,411.8厘米。基于八个环境中的表型数据和最佳线性无偏预测（BLUP）值，鉴定出五个与SNS相关的数量性状位点（QTLs），其解释了6.71-29.40%的表型变异。其中，QSns.sau-AM-2B.2和QSns.sau-AM-3B.2被鉴定为主要的、新颖的QTL。通过使用紧密连锁的kompetitive allele-specific PCR（KASP）标记，在两个额外的F2群体中进一步验证了它们的效果。预测潜在候选基因位于相应QTLs的物理区间内，可能参与花序发育和小穗形成。同时，还检测并分析了SNS与其他农艺性状之间的遗传关联。本研究证明了专为普通小麦开发的55K SNP芯片在四倍体群体遗传图谱构建中的可行性，并展示了小麦相关物种在小麦改良计划中的潜在应用。