Pleiotropic QTL Clusters for the Genetic Dissection of Yield Traits in Recombinant Inbred Line Wheat ( Triticum aestivum L.) Populations

ABSTRACT Thousand grain weight (TGW), kernel length (KL) and kernel width (KW) significantly influence yield improvement of wheat. In this study, one recombinant inbred line (RIL) population derived from a cross between Yangmai 4 (YM4) and Yanzhan 1 (YZ1) was used to identify quantitative trait loci (QTL) for TGW, KL and KW across 2 years. A total of 10 QTL were identified on chromosomes 1A, 2D, 4B and 4D, explaining 4.60%–16.67% of the phenotypic variances. Notably, four QTL clusters, namely, QTGW/KW.yaas‐1A , QTGW/KL/KW.yaas‐2D , QTGW/KL/KW.yaas‐4B and QTGW/KW.yaas‐4D , accounted for 4.60%–8.59%, 10.09%–16.67%, 5.72%–14.32% and 5.16%–11.59% of the phenotypic variances, respectively. QTGW/KW.yaas‐4D colocated with dwarfing gene Rht‐D1 . QTGW/KL/KW.yaas‐4B was a novel QTL cluster for yield traits. The positive alleles of QTGW/KL/KW.yaas‐2D and QTGW/KW.yaas‐4D significantly increased the percentage of symptomatic spikelets (PSS) and plant height (PH), respectively. The former is unfavourable to food security, whereas the latter is prone to lodging, which is unfavourable for the improvement of both grain yield and quality. QTGW/KW.yaas‐1A and QTGW/KL/KW.yaas‐4B have minimal effects on fusarium head blight (FHB) resistance or other agronomic traits. Breeder‐friendly Kompetitive Allele‐Specific PCR (KASP) markers for QTGW/KW.yaas‐1A and QTGW/KL/KW.yaas‐4B were developed and validated in a set of 138 advanced lines derived from Yangmai 158/Zhenmai 9 (YM158/ZM9). The candidate genes for QTGW/KW.yaas‐1A and QTGW/KL/KW.yaas‐4B were predicted through gene annotation, sequence variation, expression patterns and GO enrichment analysis. Gene‐specific functional markers were developed and validated in the YM4/YZ1 RIL population of 151 families. This study improves our genetic understanding of grain‐related traits and provides a solid foundation for future cloning of the target QTL.