Identification of stripe rust adult plant resistance genes in the hard winter wheat cultivar Baker's Ann

Stripe rust, caused by Puccinia striiformis f. sp. tritici, is among the most destructive wheat (Triticum aestivum L.) diseases. Identifying resistance genes is crucial for the development of resistant cultivars. Baker's Ann, a hard winter wheat cultivar developed by Oklahoma State University, has shown stable adult plant resistance to stripe rust. To dissect the genetic basis underlying stripe rust resistance in Baker's Ann, 125 doubled haploid lines, derived from the cross OK12D22004-016 × Baker's Ann, were evaluated at the adult plant stage in the greenhouse and in field environments in Oklahoma, Kansas, and Washington. This population was genotyped using genotyping‑by‑sequencing, which produced 7268 single‑nucleotide polymorphisms for genetic mapping. Quantitative trait loci (QTLs) analysis identified six loci, four from Baker's Ann on chromosomes 2DL, 4BS, 4BL, and 7BL, and two from OK12D22004-016 on chromosomes 2AS and 2AL. Although OK12D22004-016 is susceptible in the US Great Plains, it was found to carry QYr.osu-2AS, which was linked to Yr17 on the 2N^vS translocation and explained up to 30% of the phenotypic variation but was effective in a single location in Washington. Two major QTLs were identified in Baker's Ann: QYr.osu-2DL on chromosome 2DL that explained up to 57% of the phenotypic variation, and QYr.osu-4BL on chromosome 4BL that explained up to 15% of the phenotypic variation. Resistance in Baker's Ann resulted from additive effects of the four QTLs. Kompetitive allele-specific PCR markers were developed for QYr.osu-2DL to facilitate marker-assisted selection for stripe rust resistance.