Avirulence (avr) genes occur in plant pathogenic microorganisms and modulate recognitional specificities which permit plant hosts to detect the pathogen and invoke an active defense mechanism. The long range goal of the research is to understand the molecular basis underlying this recognition system and the plant defense mechanism that it modulates. Dr. Keen has cloned and sequenced several avr genes from members of the Pseudomonas syringae group of pathogens and recently observed that one of them is inducibly expressed when bacteria are inoculated into soybean plants. This plant inducible expression of a bacterial avirulence gene constitutes an important lead in the as yet unanswered question of the biochemical function of the avirulence gene protein products. Dr. Keen will further investigate the bacterial avr genes and how they are involved in plant recognition of the pathogen. He will complete the sequencing and expression of several additional avr genes. He will study inducibility of the avrC and other avirulence genes, and the relationship of avr genes to bacterial elicitors which initiate the plant defense reaction.
