We identify the wheat stem rust resistance gene Sr50 (using physical mapping, mutation and complementation) as homologous to barley Mla, encoding a coiled-coil nucleotide-binding leucine-rich repeat (CC-NB-LRR) protein. We show that Sr50 confers a unique resistance specificity different from Sr31 and other genes on rye chromosome 1RS, and is effective against the broadly virulent Ug99 race lineage. Extensive haplotype diversity at the rye Sr50 locus holds promise for mining effective resistance genes.
This work was supported by funds provided through Grains Research and Development Corporation (CSP00161 and US00063). H.Š. and J.D. are supported by the National Program of Sustainability I (award LO1204). We are grateful to T. Richardson, D. Bhatt, S. Louis, X. Xia (CSIRO Agriculture, Australia) H. Miah and S. Hoxha (The University of Sydney, Australia) for technical assistance.