Plant, Animal & Microbe Genomes X Conference

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

Poster: Gene Isolation
            

BARLEY STEM RUST RESISTANCE GENE RPG4: IDENTIFICATION AND ANALYSIS OF CANDIDATE GENES

¹ Department of Crop and Soil Science, Washington State University, Pullman, WA 99164, USA

² Department of Plant Pathology, University of Minnesota, St.Paul, MN 55108-6030, USA

³ Department of Crop and Soil Sciences and School of Molecular Biosciences, Washington State University, Pullman, WA 99164, USA

The rpg4 locus confers resistance to the barley stem rust fungus Puccinia graminis pathotype QCC. It was genetically localized to a 100 kb region of a cv Morex 150 kb BAC clone from the long arm of barley chromosome 7(5H) between markers ARD208 and ARD2065. Sequence analysis of this BAC clone revealed three open reading frames (ORFs) with no similarity to known genes. One deduced, 80 amino acid long peptide showed homology to the tomato fungal resistance genes Cf2 and Cf5. But, in cv Morex this sequence is located 5 kbp distal to the rpg4 proximal flanking marker ARD2065. Cultivar Morex has a susceptible phenotype and linkage mapping was with cultivars Q21861 and Steptoe as a resistant and susceptible parents, respectively. If rpg4 is a Cf2/Cf5 barley analog, cv Morex may have a genomic re-arrangement near ARD2065 yielding a non-functional gene. Another possibility is that rpg4 is one of the unknown ORFs identified between the flanking markers ARD208 and ARD2065. Structural analysis of Cf2/Cf5 homology region, as well as sequence analysis of candidate ORFs from Puccinia graminis QCC susceptible and resistant barley cultivars to will be presented.