Wheat leaf rust, stem rust, stripe rust, and powdery mildew caused by the fungal pathogens Puccinia triticina, P. graminis f. sp. tritici, P. striiformis f. sp. tritici, and Blumeria graminis f. sp. tritici, respectively, are destructive diseases of wheat worldwide. Breeding durable disease resistance cultivars rely largely on continually introgressing new resistance genes, especially the genes with different defense mechanisms, into adapted varieties. Here, we describe a new resistance gene obtained by mutagenesis. The mutant, MNR220 (mutagenesis-derived new resistance), enhances resistance to three rusts and powdery mildew, with the characteristics of delayed disease development at the seedling stage and completed resistance at the adult plant stage. Genetic analysis demonstrated that the resistance in MNR220 is conferred by a single semidominant gene mapped on the short arm of chromosome 2B. Gene expression profiling of several pathogenesis-related genes indicated that MNR220 has an elevated and rapid pathogen-induced response. In addition to its potential use in breeding for resistance to multiple diseases, high-resolution mapping and cloning of the disease resistance locus in MNR220 may lead to a better understanding of the regulation of defense responses in wheat.
Bibliographical noteFunding Information:
We thank Dr. Luther Talbert and the Spring Wheat Breeding Lab at Montana State University for help with the field test at NWARC in Creston, MT and SSR primers used for genetic mapping, Dr. James Kolmer of the Cereal Disease Laboratory, St. Paul, MN 55108, USA for race identification of leaf rust collected in Creston, Montana 2010 and Dr. Robert McIntosh of the Plant Breeding Institute, Cobbitty, NSW2570, Australia for editing the manuscript. This research was supported by the Montana Wheat and Barley Committee and the BREAD program (grant IOS-0965429).