QTL Mapping of Adult Plant Resistance to Wheat Leaf Rust in the Xinong1163-4×Thatcher RIL Population

Wheat leaf rust (Lr), caused by Puccinia triticina Eriks. (Pt), is one of the most important diseases affecting wheat production worldwide. Using resistant wheat cultivars is the most economic and environmentally friendly way to control leaf rust. The Chinese wheat cultivar Xinong1163-4 has shown good resistance to Lr in field trials. To identify the genetic basis of Lr resistance in Xinong1163-4, 195 recombinant inbred lines (RILs) from the Xinong1163-4/Thatcher cross were phenotyped for Lr severity in three environments: the 2017/2018, 2018/2019, 2019/2020 growing seasons in Baoding, Hebei Province,. Bulked segregant analysis and simple sequence repeat markers were then used to identify the quantitative trait loci (QTLs) for Lr adult plant resistance (APR) in the population. As a result, six QTLs were detected, designated as QLr.hbau-1BL.1, QLr.hbau-1BL.2, and QLr.hbau-1BL.3 which were predicted to be novel. QLr.hbau-4BL, QLr.hbau-4BL.1, and QLr.hbau-3A, were identified at similar physical positions to previously reported QTLs. Based on chromosome positions and molecular marker testing, QLr.hebau-1BL and QLr.hbau-1BL.3 share similar flanking markers with Lr46, respectively. Lr46 is race-non-specific APR gene for leaf rust, stripe rust and powdery mildew. Similarly, QLr.hebau-4BL showed multiple disease resistance to leaf rust, stripe rust, Fusarium head blight and powdery mildew. The QTLs identified in this study, as well as their closely linked markers, can potentially be used for marker-assisted selection in wheat breeding.