Mapping of Stem Rust Resistance Genes from Triticum turgidum ssp. dicoccum

The fungal pathogen Puccinia graminis Pers. f. sp. tritici (Pgt) causes stem rust on wheat. Especially threatening to wheat production are the Ug99 race group (e.g. TTKSK) and TRTTF. In this study, a population of 190 recombinant inbred lines (RP883 population) derived from a cross between the susceptible tetraploid durum wheat line Rusty and the resistant cultivated emmer (T. turgidum ssp. dicoccum) accession PI 193883 was used for the identification of stem rust resistance genes. The population was genotyped with the Illumina 90K SNP beadchip and simple sequence repeat (SSR) markers, and linkage maps consisting of (no.) markers were constructed. The population was evaluated for reaction to stem rust caused by Pgt races TTKSK and TRTTF and analyzed for quantitative trait loci (QTL) associated with resistance. A major QTL explaining 60-80% of the variation associated with the TTKSK and TRTTF was identified on chromosome arm 2BL. Comparisons with other maps of 2B containing stem rust resistance genes indicated that the gene derived from PI 193883 is likely novel.  A QTL with relatively minor effects was located on chromosome arm 6AL and may be an allele of Sr13. These results indicate that PI 193883 carries two stem rust resistance genes, which should be useful for the future improvement of stem rust resistance in durum and common wheat cultivars.