"Two Pseudomonas syringae type III effectors inhibit RIN4-regulated basal defense in Arabidopsis.
Cell 121, 749-759. 2005
Kim, M.-G, L da-Cunha, A McFall, Y Belkhadir, JL Dangl and D Mackey
Summary
"Plant cells have two defense systems that detect bac terial pathogens. One is a basal defense system that recognizes complex pathogen-associated molecular patterns (PAMPs). A second system uses disease resistance (R) proteins to recognize type lll effector proteins that are delivered into the plant cell by the pathogen's type III secretion system. Here we show that these two pathways are linked. We find that two Pseudomonas syringae type III effectors, AvrRpt2 and AvrRpm1, inhibit PAMP-induced signaling and thus compromise the host's basal defense system. RIN4 is an Arabidopsis protein targeted by AvrRpt2 and AvrRpm1 for degradation and phosphorylation, respectively. We find that RIN4 is itself a regulator of PAMP signaling. The R proteins, RPS2 and RPM1, sense type III effector-induced perturbations of RIN4. Thus, R proteins guard the plant against type III effectors that inhibit PAMP signaling and provide a mecha- nistic link between the two plant defense systems. "