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This article in CS

  1. Vol. 52 No. 6, p. 2438-2445
     
    Received: May 23, 2012
    Published: October 10, 2012


    * Corresponding author(s): jjohnso@uga.edu
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doi:10.2135/cropsci2012.05.0317

Identification of Pm8 Suppressor at the Pm3 Locus in Soft Red Winter Wheat

  1. Yuanfeng Haoa,
  2. Zhenbang Chena,
  3. Yingying Wanga,
  4. Dan Blanda,
  5. Ryan Parksb,
  6. Christina Cowgerb and
  7. Jerry Johnson *a
  1. a Dep. of Crop and Soil Sciences, Univ. of Georgia, Griffin Campus, Griffin, GA 30223
    b USDA-ARS, Dep. of Plant Pathology, North Carolina State University, Raleigh, NC 27695

Abstract

The 1BL.1RS wheat (Triticum aestivum L.)–rye (Secale cereale L.) translocation possesses genes Pm8, Yr9, Lr26, and Sr31 for resistance to several major fungal pathogens of small grain cereals. However, not all wheat cultivars with the 1RS translocation are resistant to Pm8-avirulent isolates of Blumeria graminis f. sp. tritici (Bgt), the causal pathogen of wheat powdery mildew. A suppressor is postulated to limit the function of Pm8 in certain genetic backgrounds, such as ‘AGS 2000’. To illustrate the genetic basis of the suppressor in AGS 2000, a 178 recombinant inbred line (RIL) population was used by crossing AGS 2000 with another 1BL.1RS cultivar Pioneer 26R61 (Pm8 effective). A single Bgt isolate, Ken-2-5, avirulent to Pm8 and virulent to Pm3a was chosen to inoculate the entire RIL population at the seedling stage. One major quantitative trait locus (QTL), QSuPm.uga-1AS, was stably detected as having an inhibiting effect on Pm8 in AGS 2000, and the QTL was postulated to be Pm3a based on its location. Further evidence of the Pm8-suppressing nature of Pm3a was obtained when eight lines from the 2010 Gulf Atlantic Wheat Nursery were inoculated with Ken-2-5. The eight lines all have Pm8 (1BL.1RS) but were susceptible, as they also have Pm3a. In addition, a functional locus, QPm.uga-7AL, was identified in Pioneer 26R61, where it accounted for up to 41% of phenotypic variation in resistance to isolate Ken-2-5. QPm.uga-7AL was flanked by simple sequence repeat (SSR) markers Xcfa2257 and Xwmc525 on 7AL, and its relationship with other known Pm loci on this chromosome arm remains uncertain.

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Copyright © 2012. Copyright © by the Crop Science Society of America, Inc.