Plant, Animal & Microbe Genomes X Conference

January 12-16, 2002
Town & Country Convention Center
San Diego, CA

Poster: Gene Isolation
            

MAP-BASED CLONING OF THE BARLEY STEM RUST RESISTANCE GENE RPG1

¹ Department of Crop and Soil Sciences, Washingto State University, Pullman, WA 99164, USA

² Department of Crop and Soil Sciences and School of molecular Biosciences, Washington State University, Pullman, WA 99164, USA

³ Center for the Application of Molecular Biology to International Agriculture, GPO Box 3200, Canberra ACT 2601, Australia

⁴ Pioneer Hi-Bred International, Inc., 7300 NW 62nd Ave., Johnston, IA 50131, USA

⁵ Department of Plant Pathology, University of Minnesota, 1991 Upper Buford Circle, St Paul, MN 55108-6030, USA

Stem rust caused by Puccinia graminis f. sp. tritici was among the most devastating diseases of barley in the northern great plains of the United States and Canada prior to the introduction in 1942 of the stem rust resistance gene Rpg1 . Thus, Rpg1 resistance is highly durable . Extensive efforts by our laboratory to clone this gene by synteny with rice were not successful, although it did provide excellent flanking markers. Here we report the isolation of Rpg1 from barley by map-based cloning. High resolution mapping with 8,518 gametes located the gene between two crossovers approximately 0.2 cM apart. A physical map of this region covering approximately 100 kb was developed by chromosome walking utilizing an arrayed cv. Morex BAC library . Two candidate genes were identified by screening for low copy probes and sequencing. The candidate gene alleles were sequenced from resistant and susceptible cultivars. Only one of the candidate genes showed a pattern of apparent functional gene structure in the resistant cultivars and defective gene structure in the susceptible cultivars. Characterization of the candidate gene and resistant and susceptible alleles will be reported. A search of the rice genome for a Rpg1 homolog was not successful.