Identification of genomic regions controlling adult-plant stripe rust resistance in Chinese landrace Pingyuan 50 through bulked segregant analysis.

ABSTRACT Stripe rust, caused by Puccinia striiformis f. sp. tritici, is one of the most widespread and destructive wheat diseases worldwide. Growing resistant cultivars with adult-plant resistance (APR) is an effective approach for the control of the disease. In this study, 540 simple sequence repeat markers were screened to map quantitative trait loci (QTL) for APR to stripe rust in a doubled haploid (DH) population of 137 lines derived from the cross Pingyuan 50 x Mingxian 169. The DH lines were planted in randomized complete blocks with three replicates in Gansu and Sichuan provinces during the 2005-06, 2006-07, and 2007-08 cropping seasons, providing data for four environments. Artificial inoculations were carried out in Gansu and Sichuan with the prevalent Chinese race CYR32. Broad-sense heritability of resistance to stripe rust for maximum disease severity was 0.91, based on the mean value averaged across four environments. Inclusive composite interval mapping detected three QTL for APR to stripe rust on chromosomes 2BS, 5AL, and 6BS, designated QYr.caas-2BS, QYr.caas-5AL, and QYr.caas-6BS, respectively, separately explaining from 4.5 to 19.9% of the phenotypic variation. QYr.caas-5AL, different from QTL previously reported, was flanked by microsatellite markers Xwmc410 and Xbarc261, and accounted for 5.0 to 19.9% of phenotypic variance. Molecular markers closely linked to the QTL could be used in marker-assisted selection for APR to stripe rust in wheat breeding programs.