Genetic Dissection of Adult-Plant Resistance to Stripe Rust in the Winter Wheat Line Tianmin 668

Stripe rust, caused by Puccinia striiformis f. sp. tritici (Pst), is a devastating wheat disease worldwide. We dissected the genetic basis of adult-plant resistance (APR) to stripe rust in a recombinant inbred line population derived from the cross Tianmin 668 × Jingshuang 16. Following inoculation with the prevalent Pst races CYR32, CYR33, and CYR34, phenotypic evaluation across three growing seasons revealed quantitative inheritance of the resistance with high heritability. Seven APR quantitative trait loci (QTLs) were identified. The resistant parent Tianmin 668 contributed three QTLs on chromosomes 2AS, 2BS, and 2BL. The most stable QTL, QYrtj-2AS, explained 9.39 to 16.73% of the phenotypic variance and was confirmed to be Yr17 using 2NS-specific markers and whole-genome resequencing. The susceptible parent Jingshuang 16 also contributed four QTLs, including QYrtj-3BS (Yr30) and QYrtj-6BS. These QTLs explained 14.15 to 15.06% and 12.78 to 13.66% of the phenotypic variance, respectively, but exhibited less environmental stability than Yr17. Pyramiding QYrtj-2AS (Yr17) with the two additional QTLs from Tianmin 668 on chromosome 2B reduced the maximum disease severity by 33%, demonstrating significant additive effects. These results demonstrate the value of both major-effect QTLs, such as QYrtj-2AS (Yr17) and QYrtj-2BL, and environmentally responsive QTLs derived even from susceptible parents for breeding. This study provides valuable genomic resources and molecular markers for pyramiding durable stripe rust resistance in wheat.