Identifying Loci Conferring Resistance to Leaf and Stripe Rusts in a Spring Wheat Population () via Genome-Wide Association Mapping.

A previous genome-wide association study (GWAS) for leaf rust (caused by ) resistance identified 46 resistance quantitative trait loci (QTL) in an elite spring wheat leaf rust resistance diversity panel. With the aim of characterizing the pleiotropic resistance sources to both leaf rust and stripe rust (caused by f. sp. ), stripe rust responses were tested in five U.S. environments at the adult-plant stage and to five U.S. races at the seedling stage. The data revealed balanced phenotypic distributions in this population except for the seedling response to f. sp. race PSTv-37. GWAS for stripe rust resistance discovered a total of 21 QTL significantly associated with all-stage or field resistance on chromosomes 1B, 1D, 2B, 3B, 4A, 5A, 5B, 5D, 6A, 6B, 7A, and 7B. Previously documented pleiotropic resistance genes and / and tightly linked genes - and - were also detected in this population. In addition, stripe rust resistance QTL , , and colocated with leaf rust resistance loci , , and , respectively. Haplotype analysis uncovered that and were either tightly linked genes or the same gene for resistance to both stripe and leaf rusts. Single nucleotide polymorphism markers , , and for the 3B QTL conferring resistance to both rusts should be useful in incorporating the resistance allele(s) in new cultivars.