Biochemical screen to identify components of the ZAR1 immune complex
M. BAUDIN (1), N. Dina (2), G. Walker (3), V. William (4), N. Mori (2), J. Hassan (2) (1) Plant and Microbial Biology Department of UC Berkeley, U.S.A.; (2) Plant and Microbial Biology Department of UC Berkeley, U.S.A.; (3) Plant and Microbial Biology Department of UC Berkeley , U.S.A.; (4) ARS, U.S.A.

Plant pathogenic bacteria like Pseudomonas syringae use the type III secretion system to inject virulence proteins called effectors into the cytoplasm of host cells where they target and inhibit plant immunity. However, plants can evolve NOD-Like Receptors (NLRs) that are able to specifically recognize effector proteins and induce strong immunity. ZAR1 is a unique NLR protein identified in the model plant A. thaliana that is required to recognize the P. syringae effector protein HopZ1a and the Xanthomonas campestris effector protein AvrAC. Interestingly, the immune pathway induced by this ancient and evolutionarily-conserved NLR is independent of most immune-related genes characterized thus far. To identify new components of the downstream pathway activated by ZAR1 upon pathogen detection, we established a biochemical screen, based on immunoprecipitation of ZAR1 protein complexes under native conditions followed by identification of the purified proteins by mass spectrometry. We generated complemented zar1 mutants carrying the ZAR1 full length gene with a commercial epitope tag, expressed under the native ZAR1 promoter. zar1 mutants carrying the untagged construct were used as a negative control, to identify non-specific interacting proteins. We confirmed that the complemented lines are functional and display a HopZ1a-induced HR. We identified putative interacting proteins with ZAR1, and will further characterize their roles in plant immunity. This biochemical screen is a powerful and unbiased tool to identify new components of this uncharacterized immune pathway.

Abstract Number: P17-492
Session Type: Poster