Plant, Animal & Microbe Genomes X Conference

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

Workshop: Barley
            

FORWARD AND REVERSE GENETICS FOR DISSECTING BARLEY POWDERY MILDEW RESISTANCE

¹ Sainsbury Laboratory, John Innes Centre, Colney Lane, Norwich, NR47UH, UK

² Department of Plant Microbe Interactions, Max-Planck-Institut für Züchtungsforschung, Carl-von-Linne-Weg, Köln, D-50829, Germany

The powdery mildew pathogen (Blumeria graminis) can be resisted by barley either at the stage of cell wall penetration or after the fungus enters the cell. Natural variation and mutational analysis has defined two sets of independently acting host genes controlling the respective resistance types. Isolation of Ror1 and Ror2 required for penetration resistance is being pursued using a map-based cloning approach exploiting rice-barley synteny and recently available EST and rice genomic sequence. RAR1, required for post penetration resistance defined by a subset of race-specific R-genes, interacts with the protein SGT1 in the yeast two-hybrid system and in planta. Silencing of Sgt1 by biolistic introduction of RNA-interference (RNAi) constructs into single leaf epidermal cells compromised Mla-6 specified resistance, demonstrating a requirement for Sgt1 in the resistance. The single cell RNAi technology and expansion of map-based cloning resources are therefore accelerating the identification of additional molecular factors required for barley powdery mildew resistance.