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United States Department of Agriculture

Agricultural Research Service


item Valent, Barbara
item Bryan, Gregory
item Jia, Yulin
item Farrall, Leonard
item Mcadams, Sean
item Faulk, Kristina
item Morris, Levy

Submitted to: International Congress on Molecular Plant-Microbe Interactions
Publication Type: Abstract Only
Publication Acceptance Date: 7/20/2001
Publication Date: N/A
Citation: N/A

Interpretive Summary:

Technical Abstract: Pi-ta-mediated resistance in rice controls strains of the rice blast fungus, Magnaporthe grisea, that express avirulent alleles of AVR-Pita in a gene-for-gene manner. Pi-ta is a single-copy resistance gene of the NBS- LRR class. AVR-Pita encodes an infection-specific protein predicted to function as a neutral zinc metalloprotease based on homology searches and on the occurrence of an amino acid sequence motif characteristic for these proteases. Current data suggest that the Pi-ta protein is an intracellular receptor that binds to the putative mature form of the AVR-Pita protease inside the plant cell, initiating defense responses. This model raises interesting questions on the nature of the plant-fungal interface for intracellular infection hyphae, and on the mechanism by which the fungus delivers proteins into the cytosol of healthy plant cells. We are analyzing structure-function relationships for Pi-ta and AVR-Pita using in vitro mutagenesis as well as analysis of naturally occurring variation for each gene. Virulent M. grisea field isolates world-wide either lack AVR- Pita homology or contain a class of closely related avr-pita alleles that fail to trigger Pi-ta-mediated resistance. Directed evolution of Pi-ta to recognize naturally occurring avr-pita alleles should lead to new genetic tools for control of rice blast disease. We will also discuss opportunities for using fungal population biology to guide R gene deployment, leading to an immediate impact on Pi-ta efficacy in the field.

Last Modified: 08/20/2017
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