: A New Gene for Stem Rust Resistance from ssp. .

Wheat stem rust (causal organism: f. sp. ) is an important fungal disease that causes significant yield losses in barley. The deployment of resistant cultivars is the most effective means of controlling this disease. Stem rust evaluations of a diverse collection of wild barley ( ssp. ) identified two Jordanian accessions (WBDC094 and WBDC238) with resistance to a virulent pathotype ( f. sp. HKHJC) from the United States. To elucidate the genetics of stem rust resistance, both accessions were crossed to the susceptible landrace Hiproly. Segregation ratios of F and F progeny indicated that a single dominant gene confers resistance to f. sp. HKHJC. Molecular mapping of the resistance locus was performed in the Hiproly/WBDC238 F population based on 3,329 single-nucleotide polymorphism markers generated by genotyping-by-sequencing. Quantitative trait locus analysis positioned the resistance gene to the long arm of chromosome 3H between the physical/genetic positions of 683.8 Mbp/172.9 cM and 693.7 Mbp/176.0 cM. Because this resistance gene is novel, it was assigned the new gene locus symbol of with a corresponding allele symbol of . At the seedling stage, confers resistance against a number of other important f. sp. pathotypes from the United States (MCCFC, QCCJB, and TTTTF) and Africa (TTKSK) as well as an isolate (92-MN-90) of the rye stem rust pathogen (. f. sp. ) from Minnesota. The resistance conferred by can be readily transferred into breeding programs because of its simple inheritance and clear phenotypic expression.