Poster: Plant Pathogen/Symbiont Interactions

Abs # 770: Genetic and Biochemical Characterization of Host Protein Complexes containing the targets of AvrRpm1 and AvrB in Arabidopsis thaliana .

Presenter:	Belkhadir, Youssef , ybelkhad@email.unc.edu
Authors	Belkhadir, Youssef  (A)   Subramaniam, Rajagopal  (A)   Dangl, Jeffery L  (A)
Affiliations:	(A): University of North Carolina Chapel Hill

Plants can resist infection by bacterial pathogens through the specific interaction of host resistance (R) genes and pathogen avirulence (avr) genes. In these gene-for-gene relationships, it is simple to think that pathogen avirulence genes generate specific ligands that interact physically with the receptor encoded by the corresponding plant resistance gene. However, this has not been demonstrated rigorously in any case. This lack of obvious ligand-receptor interaction provoked the search for molecules acting as intermediates between the two. The Arabidopsis thaliana disease resistance gene RPM1 confers resistance against Pseudomonas syringae expressing two sequence unrelated type III effectors: AvrB and AvrRpm1. RIN4, an RPM1-interacting protein, physically interacts with these type III effector molecules in planta and is required for RPM1 mediated resistance. We are developing two synergistic approaches to characterize the “RIN4 interactome”: (1) Reduction in RIN4 levels causes characteristic morphological and biochemical changes. We have isolated 432 putative second sites mutants that suppress these changes, while still producing reduced levels of RIN4. We are currently performing several “pathotests” and biochemical assays to isolate mutants of interest. (2) Using RIN4 as an entry point, we are beginning to identify the protein complex required for RPM1 function, taking advantage of different genetic tools and various biochemical approaches: HPLC, Co-immunoprecipitations and Mass Spectrometry. This research supported by NSF Arabidopsis 2010 Project IBN-0114795.