Submitted to: Crop Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/11/2007
Publication Date: 11/7/2007
Citation: Miranda, L.M., Peruginia, L., Srnic, G., Brown Guedira, G.L., Marshall, D.S., Leath, S., Murphy, J.P. 2007. Genetic Mapping of a Triticum monococcum-derived Powdery Mildew Resistance Gene in Common Wheat. Crop Science. 47:2323-2329. Interpretive Summary: Powdery mildew disease of wheat causes yield losses in temperate growing regions of the world, including the eastern soft wheat growing region of the United States. Growing resistant varieties is the most economic and efficient control option. However, single genes conferring high levels of resistance have been quickly overcome by an extremely diverse pathogen population. There is interest developing varieties having multiple resistance genes that work together to provide longer lasting resistance. Microsatellite DNA markers were identified that are linked to a new gene for resistance to powdery mildew that was transferred from the ancestral wheat species, Triticum monococcum to the North Carolina common wheat line NCBGT96A6 (NCA6). These markers can be used by wheat breeders to deploy the resistance genes by marker-assisted breeding in developing new varieties with durable resistance to powdery mildew.
Technical Abstract: Powdery mildew of wheat (Triticum aestivum L.) is a major fungal disease caused by Blumeria graminis DC f sp. tritici. A microsatellite linkage map was developed for the T. monococcum-derived powdery mildew resistant gene present in the North Carolina germplasm line NCBGT96A6 (NCA6). Genetic analysis of F2 derived lines from the cross NCA6 X ‘Saluda’ indicated a single gene controlled powdery mildew resistance. Four microsatellite markers linked to the NCA6 Pm gene mapped to chromosome 7AL. The most likely order was Xcfa2123 - 0.9cM - Xbarc121 - 1.7cM, resistance gene/Xcfa2019 - 3.0cM - Xgwm332. A detached-leaf test indicated the disease reaction response of the NCA6 Pm gene was different from the five known alleles at the Pm1 locus on 7AL. Deletion interval mapping showed a large physical to genetic distance ratio for these microsatellite marker loci. This suppressed recombination might be due to the introgressed T. monococcum segment. Our results suggested that the NCA6 Pm gene is likely a novel source of resistance to powdery mildew but additional allelism studies are needed to establish the relationship between this locus and the other known Pm loci on 7AL.