A stable QTL on Chromosome 5BL Combined with Yr18 Conferring High-level Adult-plant Resistance to Stripe Rust in Chinese Wheat Landrace Anyuehong.

Chinese wheat landrace Anyuehong (AYH) has displayed high levels of stable adult-plant resistance (APR) to stripe rust for more than 15 years. To identify QTL for stripe rust resistance in AYH, a set of 110 recombinant inbred lines (RILs) was developed from a cross between AYH and susceptible cultivar Taichung 29. The parents and RILs were evaluated for final disease severity (FDS) in six field tests with a mixture of predominant Pst races at the adult-plant stage and genotyped using the wheat 55K SNP array to construct a genetic map with 1,143 SNP markers. Three QTL, designated as QYr.AYH-1AS, QYr.AYH-5BL and QYr.AYH-7DS, were mapped on chromosome 1AS, 5BL and 7DS, respectively. RILs combining three QTL showed significantly reduced FDS compared with the lines in other combinations. Of them, QYr.AYH-5BL and QYr.AYH-7DS were stably detected in all environments, explaining 13.6-21.4% and 17.6-33.6% of phenotypic variation, respectively. Compared with previous studies, QYr.AYH-5BL may be a new QTL, while QYr.AYH-7DS may be Yr18. Haplotype analysis revealed that QYr.AYH-5BL is likely present in 6.2% of the 323 surveyed Chinese wheat landraces. The Kompetitive allele specific PCR (KASP) markers for QYr.AYH-5BL were developed by the linked SNP markers to successfully confirm the effects of the QTL in a validation population derived from a residual heterozygous line, and were further assessed in 38 Chinese wheat landraces and 92 cultivars. Our results indicated that QYr.AYH-5BL with linked KASP markers should have potential value for marker-assisted selection to improve stripe rust resistance in breeding programs.