The barley stem rust-resistance gene Rpg1 is a novel disease-resistance gene with homology to receptor kinases

doi:10.1073/pnas.142284999

The barley stem rust-resistance gene Rpg1 is a novel disease-resistance gene with homology to receptor kinases

^*Department of Crop and Soil Sciences, Washington State University, Pullman, WA 99164-6420; ^¶Department of Plant Pathology, 495 Borlaug Hall, 1991 Upper Buford Circle, St. Paul, MN 55108-6030; and ^‖School of Molecular Biosciences, Washington State University, Pullman, WA 99164-4234

Communicated by Diter von Wettstein, Washington State University, Pullman, WA (received for review March 25, 2002)

Abstract

Stem rust caused by Puccinia graminis f. sp. tritici was among the most devastating diseases of barley in the northern Great Plains of the U.S. and Canada before the deployment of the stem rust-resistance gene Rpg1 in 1942. Since then, Rpg1 has provided durable protection against stem rust losses in widely grown barley cultivars (cvs.). Extensive efforts to clone Rpg1 by synteny with rice provided excellent flanking markers but failed to yield the gene because it does not seem to exist in rice. Here we report the map-based cloning and characterization of Rpg1. A high-resolution genetic map constructed with 8,518 gametes and a 330-kb bacterial artificial chromosome contig physical map positioned the gene between two crossovers ≈0.21 centimorgan and 110 kb apart. The region including Rpg1 was searched for potential candidate genes by sequencing low-copy probes. Two receptor kinase-like genes were identified. The candidate gene alleles were sequenced from resistant and susceptible cvs. Only one of the candidate genes showed a pattern of apparently functional gene structure in the resistant cvs. and defective gene structure in the susceptible cvs. identifying it as the Rpg1 gene. Rpg1 encodes a receptor kinase-like protein with two tandem protein kinase domains, a novel structure for a plant disease-resistance gene. Thus, it may represent a new class of plant resistance genes.

Footnotes

↵ † Present address: Center for the Application of Molecular Biology to International Agriculture, GPO Box 3200, Canberra ACT 2601, Australia.
↵ ‡ Present address: Pioneer Hi-Bred International Inc., 7300 NW 62nd Avenue, Johnston, IA 50131.
↵ § Present address: U.S. Department of Agriculture/Agricultural Research Service Plant Stress and Germplasm Lab, 3810 4th Street, Lubbock, TX 79415.
↵ ** To whom reprint requests may be addressed. E-mail: andyk{at}wsu.edu.
Data deposition: The sequences reported in this paper have been deposited in the GenBank database [accession nos. AF509747 (Rpg1 cDNA); AF509748–AF509765 (Rpg1 genomic sequences from barley lines Morex, OSU6, Q21861, 80-TT, Bowman, Chevron, Leger, Kindred, Peatland, Steptoe, Lion, Wisconsin 38, Moravian III, OSU15, SM89010, Dicktoo, Gobernadora, and AMS170, respectively); AF509744–AF509746 (NRG031 genomic sequence from barley lines Morex, Steptoe, and OSU6, respectively); AF509766–AF509779 (genomic sequences from low copy probes isolated from the Rpg1 genomic region NRG019, NRG021, NRG026, NRG027, NRG046, NRG048, NRG050, RSB347, RSB409A, RSB409B, RSB410, RSB414, and RSB416, respectively)].
Abbreviations:

BAC,

bacterial artificial chromosome;

cv.,

cultivar;

LRR,

leucine-rich repeat;

RT,

reverse transcription;

cM,

centimorgan