Mapping QTLs for adult-plant resistance to yellow rust in a hard winter wheat population Heyne × Lakin.

Adult-plant resistance to yellow rust, caused by Puccinia striiformis f. sp. tritici, is a durable type of resistance in wheat (Triticum aestivum L.). To map the quantitative trait loci (QTLs) for adult-plant resistance, 145 (Heyne × Lakin)F_6:7 recombinant inbred lines (RILs) were evaluated for rust infection type (IT) and maximum rust severity (MRS) in multiple environments and genotyped using single-nucleotide polymorphisms (SNPs) derived from 9 K SNP chips and simple sequence repeat markers. Four major QTLs on chromosome arms 2AS (QYr.hwwgr-2AS), 2AL (QYr.hwwgr-2AL), 2BL (QYr.hwwgr-2BL) and 3BS (QYr.hwwgr-3BS) were identified for adult-plant resistance in multiple environments with their resistance alleles all from Heyne, except for QYr.hwwgr-3BS. QYr.hwwgr-2AS and QYr.hwwgr-2BL were significant for both IT and MRS. QYr.hwwgr-2AS showed the largest effect, explaining 10.6-51.3% of the phenotypic variance for MRS in four environments and 31.0% phenotypic variance for low IT in one experiment. QYr.hwwgr-2BL might be a new QTL in a 0.7-cM interval and explained 7.5-22.1% of the phenotypic variance of IT and 10.3-19.0% of the phenotypic variance of MRS. QYr.hwwgr-2AL was mapped at a 3.4-cM interval and explained 4.2-10.7% of the phenotypic variance for IT. QYr.hwwgr-3BS was identified at a 0.7-cM interval, accounting for 5.5-13.6% of the phenotypic variance for IT. Stacking all four QTLs in a single RIL can achieve a low IT of 0-2, which is significantly lower than the resistant parent Heyne.