Plant, Animal & Microbe Genomes X Conference

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

Poster: Functional Genomics for Microorganisms
            

TOWARD THE CLONING OF VIRULENCE GENES IN THE PLANT PATHOGENIC FUNGUS COCHLIOBOLUS SATIVUS

¹ Department of Plant Pathology, University of Minnesota, St. Paul, MN 55108, USA

² Department of Botany and Plant Pathology, Oregon State University, Corvallis, OR 97331

Cochliobolus sativus is a plant pathogenic fungus that causes spot blotch on barley and wheat. Virulence on barley cultivar Bowman and wheat line PI53054 was previously determined to be controlled by a single locus in isolates ND90Pr and ND93-1, respectively. To clone these virulence loci through a map-based cloning strategy, we have constructed a molecular genetic map based on a cross between isolates ND90Pr and ND93-1. The genetic map consists of 27 linkage groups with 97 AFLP markers, 31 RFLP markers, two PCR amplified markers, the mating type locus (CsMAT), and the gene (VHv1) conditioning high virulence on Bowman. The virulence gene VHv1 cosegregated with six AFLP markers and was mapped to one of the major linkage groups. Two of the six co-segregating AFLP markers were cloned and found unique to isolates virulent on Bowman. We also resolved fourteen chromosome-sized DNAs in isolates ND93-1 and ND90Pr with contour-clamped homogeneous electric field (CHEF) electrophoresis, combined with a telomere probe. Hybridization of RFLP and AFLP markers mapped from individual linkage groups with CHEF blots allowed 24 of the 27 linkage groups to be assigned to specific chromosomes. The chromosome carrying VHv1 was separated from isolate ND90Pr and will be used to construct a chromosome-specific DNA library. Construction of the genetic map, coupled with the identification of closely linked molecular markers, will facilitate the cloning of the virulence gene VHv1 in C. sativus by map-based cloning.