Combining genome-wide linkage mapping with extreme pool genotyping for stripe rust resistance gene identification in bread wheat

Stripe rust, caused by Puccinia striiformis f. sp. tritici (Pst), is one of the most important diseases of wheat (Triticum aestivum) in China and is responsible for major production losses worldwide. Wheat cultivar Centrum was resistant at seedling stage to Chinese Pst isolate V26-10. To map the gene(s) conferring resistance, Centrum was crossed with the susceptible cultivar MX169. Genetic analysis of F1, F2, F2:3, and F2:6 populations showed that resistance was conferred by a single recessive gene, tentatively named Yrcen. The F2:6 population was genotyped using Illumina 35 K SNP (single nucleotide polymorphism) assays. Gene Yrcen was located on chromosome 1DS. To saturate the genetic map, the Affymetrix Wheat 660 K SNP array was used to screen bulked extreme phenotype DNA pools. Eight SNPs were located around the resistance gene. After combining SNP data from both the 35 K and 660 K assays, Yrcen was mapped to an interval of 1.7 cM flanked by markers AX-94530296 and AX-94434109. These two markers were validated for marker assisted selection of Yrcen using a panel of 96 wheat cultivars and breeding lines. These tightly linked markers will be useful in developing cultivars for resistance to stripe rust.