Submitted to: Euphytica
Publication Type: Peer reviewed journal
Publication Acceptance Date: 12/17/2006
Publication Date: 3/8/2007
Citation: Tucker, D.M., Griffey, C.A., Liu, S., Brown Guedira, G.L., Marshall, D.S., Saghai-Maroof, M. 2007. Confirmation of Three Quantitative Trait Loci Conferring Adult Plant Resistance to Powdery Mildew in Two Winter Wheat Populations. Euphytica. 155:1-13. 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 adult-plant resistance genes that work together to provide longer lasting resistance. Resistance to powdery mildew in the soft wheat cultivar ‘Massey’ has been effective for more than 20 years and remains effective in varieties derived from Massey. In this study, new molecular marker linked to three genes that contribute to the resistance in Massey and its derivative ‘USG 3209’ were identified. 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: Hypersensitive, race specific genes primarily have been deployed to control powdery mildew (caused by Blumeria graminis) in wheat (Triticum aestivum); however, recent efforts have shifted to breeding for more durable resistance. Previously, three QTL for adult plant resistance (APR) to powdery mildew in the winter wheat cultivar Massey were identified in a Becker by Massey (BM) F2:3 population. Fourteen new simple sequence repeat (SSR) markers were added to the pre-existing BM F2:3 linkage maps near the QTL for APR on chromosomes 1B (QPm.vt-1B), 2A (QPm.vt-2A), and 2B (QPm.vt-2B). Genetic linkage maps comprised of 17 previously and newly mapped SSRs from the BM population on chromosomes 1B, 2A, and 2B were constructed in a USG 3209 by Jaypee (UJ) F6:7 recombinant inbred line (RIL) confirmation population, wherein the APR resistance of USG 3209 is derived from Massey. Interval mapping analysis of mildew severity data collected in 2002 (F5:6) and 2003 (F6:7) field experiments with marker genotypic data obtained in 2003 (F6:7) confirmed the presence of the three QTL governing APR to powdery mildew in the UJ RILs. The QTL QPm.vt-1B, QPm.vt-2A, and QPm.vt-2B explained 12% to 13%, 59% to 69%, and 22% to 48% of the phenotypic variance for powdery mildew severity in the UJ confirmation populations, respectively, in two field experiments. The current study verifies that the elite wheat cultivar USG 3209 possesses the same QTL for APR as its parent Massey. Marker-assisted selection can now be applied and evaluated for its effectiveness in breeding population having APR to powdery mildew derived from Massey or its relatives.