Molecular Mapping of Quantitative Trait Loci for Stripe Rust Resistance in Wheat Landrace PI 622129

Wheat stripe rust, caused by the biotrophic fungal pathogen <i>Puccinia striiformis</i> f. sp. <i>tritici</i> (<i>Pst</i>), is among the top crop diseases incurring huge economic losses worldwide. Identification of new stripe rust-resistant sources that can be easily used in wheat cultivar development is essential for food security. PI 622129, an Iranian wheat landrace, exhibits high resistance to the predominant U.S. <i>Pst</i> races. A recombinant inbred line (RIL) population from the cross PI 622129 × Stardust was genotyped using single-nucleotide polymorphisms generated by genotyping-by-sequencing. The RIL population was evaluated for responses to the <i>Pst</i> race PSTv-37 at the seedling stage in three environments, and quantitative trait loci (QTLs) analysis revealed four QTLs for stripe rust resistance on chromosome arms 2DS, 5BS, 2AL, and 7BL. Of these, <i>QYr.stars-2DS</i> and <i>QYr.stars-5BS</i> are major QTLs that explained 21 to 38% and 11.6 to 27.2% of the total phenotypic variance, respectively, in three experiments. <i>QYr.stars-2DS</i> is a new stripe rust resistance locus that was identified in the interval of 2.58 to 5.54 Mb on chromosome arm 2DS based on the Chinese Spring IWGSC RefSeq v.2.1 reference genome. Another QTL, <i>QYr.stars-5BS</i>, is close to <i>Yr47</i> and was delimited to the interval 8.1 to 9.0 Mb in the reference genome. <i>QYr.stars-2AL</i> and <i>QYr.stars-7BL</i> were mapped to the terminal and QTL-rich regions on chromosome arms 2AL (750.8 to 752.5 Mb) and 7BL (718.1 to 721.2 Mb), respectively. KASP markers were developed to facilitate rapid introgression of these QTLs into locally adapted lines via marker-assisted selection.