QTL Mapping of Adult Plant Resistance to Leaf Rust in the N. Strampelli × Huixianhong RIL Population

Leaf rust (LR) is a destructive foliar disease that affects common wheat (Triticum aestivum L.) worldwide. For optimal disease protection, wheat cultivars should possess adult plant resistance (APR) to leaf rust. The aim of the present study was to map quantitative trait loci (QTLs) for leaf rust resistance using 193 recombinant inbred line (RIL) populations derived from N. Strampelli × Huixianhong. Four trials were conducted in China (three in Baoding, Hebei province, and one in Zhoukou, Henan province) to assesses the leaf rust response of the RILs and parental lines. The RIL populations were genotyped using the wheat 660K SNP array and additional SSR markers. Three QTLs for LR resistance were identified using inclusive composite interval mapping (ICIM). Previously published data were also reassessed with ICIM to identify QTLs with pleiotropic effects. The flanking sequences of all SNP probes were searched against the Chinese Spring wheat reference sequence using BLAST to determine physical positions. Three leaf rust resistance loci, two on chromosome 2A and 5B, were contributed by N. Strampelli. QLr.hbau-2AL.1 detected in three leaf rust environments with phenotypic variance explained (PVE); QLr.hbau-2AL.2 detected in two environments with 12.5-13.2% of the PVE; QLr.hbau-5BL detected in all leaf rust environments with phenotypic variance explained (PVE) of 17.8-19.1%. QLr.hbau-5BL exhibited potentially pleiotropic responses to multiple diseases. The QTLs and flanking markers identified herein may be useful for fine mapping, candidate gene mining, and marker-assisted selection(MAS).