Two QTL for kernel number per spike identified from durum wheat

As one of the three yield components, kernel number per spike (KNPS) plays a key role in determining wheat yield. In this study, in combination with the previously constructed genetic map for a tetraploid wheat recombinant inbred line (RIL) population developed from the cross between a durum wheat and a wild emmer wheat and phenotype data from four environments, two major and stably expressed quantitative trait loci (QTL) for KNPS were identified. The phenotypic variation explained by these two QTL, <i>Qknps-DW-3A.1</i> and <i>Qknps-DW-3A.2</i>, was up to 12.52% and 29.52%, respectively. The positive alleles were both from the durum wheat. Pyramiding analysis suggested that the combination of these two positive alleles has the largest effect on increasing KNPS. Comparison of physical interval for these two QTL with those reported previously showed that they may be novel loci. Genetic correlations between KNPS and other agronomic traits were also evaluated. Taken together, the two major and stably expressed QTL for KNPS from tetraploid wheat reported here they should be useful in wheat breeding.作为小麦三大产量构成因子之一，每穗粒数（kernel number per spike，KNPS）在小麦产量形成过程中发挥关键作用。本研究结合此前构建的、由硬粒小麦与野生二粒小麦杂交获得的四倍体小麦重组自交系（recombinant inbred line，RIL）群体遗传图谱，以及4个环境下的表型数据，鉴定到2个可稳定表达的每穗粒数主效数量性状位点（quantitative trait loci，QTL）。这两个分别命名为Qknps-DW-3A.1与Qknps-DW-3A.2的QTL，各自可解释的表型变异率最高可达12.52%与29.52%，其增效等位基因均来自硬粒小麦。聚合分析结果显示，同时聚合这两个增效等位基因对提升每穗粒数的增效效果最为显著。将这两个QTL的物理区间与此前已报道的位点进行比对后发现，它们可能为全新的遗传位点。本研究还评估了每穗粒数与其他农艺性状间的遗传相关性。综上，本研究报道的来自四倍体小麦的2个每穗粒数主效稳定QTL，具备小麦育种应用价值。