Submitted to: Journal of Theoretical and Applied Genetics
Publication Type: Peer reviewed journal
Publication Acceptance Date: 11/10/2007
Publication Date: 12/19/2007
Citation: Perugini, L., Murphy, J., Marshall, D.S., Brown Guedira, G.L. 2007. Pm37, a new broadly effective powdery mildew resistance gene from Triticum timopheevii . Journal of Theoretical and Applied Genetics. 116:417-425. Interpretive Summary: Powdery mildew is a fungal disease that can cause yield losses in wheat in temperate growing regions of the world. In the Eastern United States, powdery mildew has caused grain yield reductions, and can significantly reduce flour yield and adversely affect other aspects of grain quality. The use of resistant cultivars is an effective, economical and environmentally safe approach to eliminate the use of fungicides and to reduce production losses due to this disease. In this study, we analyzed the resistance to powdery mildew in a winter wheat line that was developed from a cross between wheat and a wild ancestor of wheat, T. timopheevii subsp. armeniacum. As a result of this analysis, the resistance gene was determined to be new gene for powdery mildew resistance and given the designation Pm37. Closely linked DNA markers or tags for the powdery mildew resistance gene were identified. These molecular tags can be used by wheat breeders to select new powdery mildew resistant varieties.
Technical Abstract: Powdery mildew, caused by Blumeria graminis f. sp. tritici, is an important foliar disease in wheat (Triticum aestivum L.), especially in areas with a cool or maritime climate. A dominant powdery mildew resistance gene transferred to the hexaploid germplasm line NC99BGTAG11 (NCAG11) from T. timopheevii subsp. armeniacum was mapped distally on the long arm of chromosome 7A. Differential reactions were observed between the resistance gene in NCAG11 and the alleles of the Pm1 locus that is also located on chromosome arm 7AL. Observed segregation in F2:3 lines from the cross NCAG11 x Axminster (Pm1a) demonstrate that germplasm line NCAG11 carries a novel powdery mildew resistance gene, which is now designated as Pm37. Analyses of the population with molecular markers indicate that Pm37 is located approximately 16cM proximal to the Pm1 complex. Simple sequence repeat (SSR) markers Xgwm332 and Xwmc790 were located 0.5cM proximal and distal, respectively, to Pm37. In order to identify new markers in the region, wheat expressed sequence tags (ESTs) located in the distal 10% of 7AL that were orthologous to sequences from chromosome 6 of rice were targeted. The two new EST-derived STS markers were located distal to Pm37 and one marker was closely linked to the Pm1a region. These new markers can be used in marker-assisted selection schemes to develop wheat cultivars with pyramids of powdery mildew resistance genes, including combinations of Pm37 in coupling linkage with alleles of the Pm1 locus.