High density mapping of wheat stripe rust resistance gene QYrXN3517-1BL using QTL mapping, BSE-Seq and candidate gene analysis

Fine mapping of a major stripe rust resistance locus QYrXN3517-1BL to a 336 kb region that includes 12 candidate genes. Utilization of genetic resistance is an effective strategy to control stripe rust disease in wheat. Cultivar XINONG-3517 (XN3517) has remained highly resistant to stripe rust since its release in 2008. To understand the genetic architecture of stripe rust resistance, Avocet S (AvS) × XN3517 F6 RIL population was assessed for stripe rust severity in five field environments. The parents and RILs were genotyped by using the GenoBaits Wheat 16 K Panel. Four stable QTL from XINONG-3517 were detected on chromosome arms 1BL, 2AL, 2BL, and 6BS, named as QYrXN3517-1BL, QYrXN3517-2AL, QYrXN3517-2BL, and QYrXN3517-6BS, respectively. Based on the Wheat 660 K array and bulked segregant exome sequencing (BSE-Seq), the most effective QTL on chromosome 1BL is most likely different from the known adult plant resistance gene Yr29 and was mapped to a 1.7 cM region [336 kb, including twelve candidate genes in International Wheat Genome Sequencing Consortium (IWGSC) RefSeq version 1.0]. The 6BS QTL was identified as Yr78, and the 2AL QTL was probably same as QYr.caas-2AL or QYrqin.nwafu-2AL. The novel QTL on 2BL was effective in seedling stage against the races used in phenotyping. In addition, allele-specifc quantitative PCR (AQP) marker nwafu.a5 was developed for QYrXN3517-1BL to assist marker-assisted breeding.