Genetic Mapping of Race-Specific Stem Rust Resistance in the Synthetic W97846 x Opata85 Mapping Population

Stem rust (Puccinia graminis tritici L.) has historically caused severe yield losses of wheat (Triticum aestivum L.) worldwide and has been one of the most feared diseases to wheat and barley (Hordeum vulgare L.).  Stem rust has been controlled successfully through the use of resistant varieties.  However, stem rust race Ug99 (Puccinia graminis Pers. f. sp. tritici Eriks. & E. Henn.) and its derivatives are virulent to widely many widely deployed stem rust resistance genes including Sr31, Sr24, and Sr36.  Doubled haploid lines from the Synthetic W7984 x Opata M85 wheat reference population were screened for seedling resistance to stem rust races TRTTF and QTHJC.  Infection types were scored 14 days after inoculation according to the Stakman scale.  The phenotypic data was adjusted to a 1 to 5 scale and quantitative trait loci (QTLs) for resistance to TRTTF and QTHJC were identified by Composite Interval Mapping.  Major large effect QTL for resistance to stem rust races TRTTF and QTHJC were identified on chromosomes 2BS, 6AS and 6AL.