扬麦17/ 宁麦18的F2群体穗部性状QTL定位

小麦穗部性状特别是穗顶部、基部结实性对穗粒数的建成及产量具有重要影响。为给QTL精细定位、基因克隆及穗部性状分子标记的开发和辅助选择奠定基础，本研究以扬麦17与宁麦18杂交获得的310个F₂群体及其衍生的F_2:3家系为材料，构建了一个由215个SSR标记组成的全长为1 717 cM的遗传连锁图谱，共覆盖19条染色体（1D和6A未涉及），标记间平均距离为7.99 cM，并对6个穗部性状进行QTL定位。利用复合区间作图法共检测出22个QTL，分布在1A、1B、2B、2D、3B、3D、4B、5A、5B和7A染色体上。其中，穗顶部结实粒数QTL有7个，穗基部结实粒数QTL有2个，穗长QTL有5个，总小穗数QTL有3个，不育小穗数QTL有2个，穗粒数QTL有3个，表型贡献率为2.56%～13.66%。控制穗顶部和基部结实粒数QTL的增效基因来源于宁麦18，表明该品种可作为具有高产潜力的小麦育种材料加以利用。

QTL Mapping for Spike Traits in Wheat(Triticum aestivum L.) Using the F2 Population of Yangmai 17/Ningmai 18

Spike traits are closely related to the yield of wheat,especially the rates of grain-setting in apical and basal spikelets directly affect the grain number per spike(GNS). In this study,the population of 310 F₂ and its F_2:3 generations derived from the across between Yangmai 17 and Ningmai 18 were used to detect the quantitative trait loci(QTLs) for these traits. The genetic linkage map consists of 215 simple sequence repeat(SSR) markers covering 19 chromosomes except for 1D and 6A,with the length of 1 717 cM and an average genetic distance of 7.99 cM. A total of 22 QTLs for all traits were mapped on 1A,1B,2B,2D,3B,3D,4B,5A,5B and 7A chromosomes by Composite Interval Mapping(CIM) based on the genetic map and phenotypic data. Among the detected QTLs for spike traits,seven QTLs for grain number in apical spikelets(GNAS) explained the phenotypic variation ranging from 4.01% to 8.79%; two QTLs for grain number in basal spikelets(GNBS) explained 4.78% to 8.04% of the phenotypic variation; five QTLs explained 2.56% to 8.98% of the phenotypic variation for spike length(SL); three QTLs for total spikelet number per spike(TSS) explained the phenotypic variation ranging from 4.23% to 13.66%; two QTLs for sterile spikelet number per spike(SSS) explained 3.70% to 6.01% of the phenotypic variation; and three QTLs explained 2.56% to 7.94% of the GNS variation. All of the QTLs controlling GNAS and GNBS were contributed by Ningmai 18,indicating that the genetic material could be used to improve yield effectively in breeding. Our results provided an important foundation not only for QTL fine mapping and cloning,but also for molecular marker development and marker-assisted selection of the spike-related traits in wheat.