Genome-Wide Linkage Mapping of QTL for Adult-Plant Resistance to Stripe Rust in a Chinese Wheat Population Lantian 25 × Huixianhong

Stripe rust, caused by <i>Puccinia striiformis</i> f. sp. <i>tritici</i> (Pst), represents a major global threat to wheat (<i>Triticum aestivum</i>. L). Planting varieties with adult-plant resistance (APR) is an effective approach for long-term management of this disease. The Chinese winter wheat variety Lantian 25 exhibits moderate-to-high APR against stripe rust under field conditions. To investigate the genetic basis of APR in Lantian 25, a set of 219 F₆ recombinant inbred lines (RILs) was created from a cross between Lantian 25 (resistant parent) and Huixianhong (susceptible parent). These RILs were assessed for maximum disease severity (MDS) in Pixian of Sichuan and Qingshui of Gansu over the 2020-2021 and 2021-2022 growing seasons, resulting in data from four different environments. Genotyping was performed on these lines and their parents using the wheat Illumina 50K single-nucleotide polymorphism (SNP) arrays. Composite interval mapping (CIM) identified six quantitative trait loci (QTL), named <i>QYr.gaas-2BS</i>, <i>QYr.gaas-2BL</i>, <i>QYr.gaas-2DS</i>, <i>QYr.gaas-2DL</i>, <i>QYr.gaas-3BS</i> and <i>QYr.gaas-4BL</i>, which were consistently found across two or more environments and explained 4.8-12.0% of the phenotypic variation. Of these, <i>QYr.gaas-2BL</i>, <i>QYr.gaas-2DS</i>, and <i>QYr.gaas-3BS</i> overlapped with previous studies, whereas <i>QYr.gaas-2BS</i>, <i>QYr.gaas-2DS</i>, and <i>QYr.gaas-4BL</i> might be novel. All the resistance alleles for these QTL originated from Lantian 25. Furthermore, four kompetitive allele-specific PCR (KASP) markers, <i>Kasp_2BS_YR</i> (<i>QYr.gaas-2BS</i>), <i>Kasp_2BL_YR</i> (<i>QYr.gaas-2BL</i>), <i>Kasp_2DS_YR</i> (<i>QYr.gaas-2DS</i>) and <i>Kasp_2DL_YR</i> (<i>QYr.gaas-2DL</i>), were developed and validated in 110 wheat diverse accessions. Additionally, we identified seven candidate genes linked to stripe rust resistance, including disease resistance protein RGA2, serine/threonine-protein kinase, F-box family proteins, leucine-rich repeat family proteins, and E3 ubiquitin-protein ligases. These QTL, along with their associated KASP markers, hold promise for enhancing stripe rust resistance in wheat breeding programs.