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This article in TPG

  1. Vol. 2 No. 2, p. 109-120
    Received: Feb 18, 2009



Barley Stem Rust Resistance Genes: Structure and Function

  1. Andris Kleinhofs ,
  2. Robert Brueggeman,
  3. Jayaveeramuthu Nirmala,
  4. Ling Zhang,
  5. Aghafakhr Mirlohi,
  6. Arnis Druka,
  7. Nils Rostoks and
  8. Brian J. Steffenson
  1. A. Kleinhofs, Dep. Crop and Soil Sciences and School of Molecular Biosciences, Washington State Univ., Pullman, WA 99164-6420; R. Brueggeman and J. Nirmala, Dep. Crop and Soil Sciences, Washington State Univ., Pullman, WA 99164-6420; L. Zhang, Dep. Biochemistry and Molecular Biology, Univ. of Miami, Miami, FL 33136; A. Mirlohi, College of Agriculture, Isfahan Univ. of Technology, Isfahan, 84156-83111, Iran; A. Druka, Scottish Crop Research Institute, Invergowrie, Dundee, DD2 5DA,Scotland, UK; N. Rostoks, Faculty of Biology, Univ. of Latvia, 4 Kronvalda Boulevard, Riga, LV-1586, Latvia; B.J. Steffenson, Dep. of Plant Pathology, Univ. of Minnesota, St. Paul, MN 55108-6030. Research in AK and BJS laboratories was supported by multiple grants over many years by the National Research Initiative of the USDA Cooperative State Research, Education and Extension Service, recent grant numbers #2004-35301-14635 and #2007-35301-18205. Research in BJS laboratory was also funded in part by the Lieberman-Okinow Endowment.


Rusts are biotrophic pathogens that attack many plant species but are particularly destructive on cereal crops. The stem rusts (caused by Puccinia graminis) have historically caused severe crop losses and continue to threaten production today. Barley (Hordeum vulgare L.) breeders have controlled major stem rust epidemics since the 1940s with a single durable resistance gene Rpg1. As new epidemics have threatened, additional resistance genes were identified to counter new rust races, such as the rpg4/Rpg5 complex locus against races QCCJ and TTKSK. To understand how these genes work, we initiated research to clone and characterize them. The Rpg1 gene encodes a unique protein kinase with dual kinase domains, an active kinase, and a pseudokinase. Function of both domains is essential to confer resistance. The rpg4 and Rpg5 genes are closely linked and function coordinately to confer resistance to several wheat (Triticum aestivum L.) stem rust races, including the race TTKSK (also called Ug99) that threatens the world's barley and wheat crops. The Rpg5 gene encodes typical resistance gene domains NBS, LRR, and protein kinase but is unique in that all three domains reside in a single gene, a previously unknown structure among plant disease resistance genes. The rpg4 gene encodes an actin depolymerizing factor that functions in cytoskeleton rearrangement.

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