Project Number: 3655-22000-018-00
Project Type: Appropriated

Start Date: Jun 25, 2007
End Date: Jun 24, 2012

Objective:
The long-term objective of this research is to better understand the components of molecular recognition of the rice blast fungus in order to design new disease management strategies for durable resistance. Over the next 5 years, we will focus on the following objectives: Objective: Determine the components of the AVR1-CO39 and Pi-CO39 interaction in rice. Subobjective: Determine if AVR and resistance gene products interact directly in rice and without modification.

Approach:
We have cloned the AVR1-CO39 avirulence gene from M. oryzae and have isolated candidate resistance genes mapping at the corresponding Pi-CO39(t) resistance gene locus. Collaborators Tosa and coworkers have cloned homologs of AVR1-CO39 from many nonrice-infecting isolates of M. oryzae while Farman has cloned homologs from perennial rye isolates. Functional homologs are widespread in Magnaporthe oryzae. Full understanding of the molecular bases of this host-parasite interaction will require understanding if the product of the Pi-CO39(t) interacts directly with that of AVR1-CO39 and whether other host or pathogen components are involved. The elucidation of the structure of orf3 of AVR1-CO39 is needed to better understand whether an EF-like hand is present and calcium is bound and how these affect structure and function. These studies are needed to better understand how AVR1-CO39 signals the presence of the fungus and elicits the defense response. Determination of the timing and location of expression of these cell components and their effect on fungal and host growth and development will provide further insight into the question of how resistance is mediated at the cellular level. The aims of this proposal are designed to better understand this disease resistance mechanism in order to engineer new strategies to control rice blast disease.