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.

CSIRO Agriculture GPO Box 1600 Canberra ACT 2601 Australia

Department of Plant Sciences University of California Davis California 95616 USA

INRA CNRGV 24 Chemin de Borde Rouge Auzeville CS 52627 Castanet Tolosan Cedex 31326 France

Institute of Experimental Botany Centre of the Region Haná for Biotechnological and Agricultural Research Šlechtitelů 31 Olomouc CZ 78371 Czech Republic

Plant Breeding Institute The University of Sydney Private Bag 4011 Narellan New South Wales 2567 Australia

USDA ARS Cereal Disease Laboratory University of Minnesota Saint Paul Minnesota 55108 USA

References provided by Crossref.org

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Divergence between bread wheat and Triticum militinae in the powdery mildew resistance QPm.tut-4A locus and its implications for cloning of the resistance gene