RPS2 Innate Immunity

Peudomonas syringae

RPS2 Disease Resistance Signaling Pathway 



 

During the last fifteen years my laboratory has been developing the Arabidopsis/Pseudomomas host-pathogen interaction system to elucidate the molecular basis of pathogen recognition and the subsequent defense signaling pathways specifying plant innate immunity. Our research has mainly concentrated on the RPS2 disease resistance-signaling pathway.

Tomato infected with Peudomonas syringae

The RPS2 disease resistance protein is the prototypic member of the CC/NB/LRR subclass of the NB/LRR “superfamily” of plant immune receptors. The RPS2 resistance gene encodes for an approximately 105kD protein and specifically recognizes the AvrRpt2 Pseudomonas TTSS effector protein to trigger a resistance response that results in inhibition of bacterial growth.  

Previous work in our laboratory has shown that the AvrRpt2-mediated elimination of RIN4 occurs shortly after the AvrRpt2 effector protein is delivered to the plant cell via the TTSS (Type Three Secretion System) of Peudomonas syringae. The avrRpt2 effector gene encodes a 28kD  cysteine protease that recognizes a proteolytic cleavage site in both AvrRpt2 which results in the elimination of the RIN4 protein that activates the RPS2 signaling pathway.  We have also demonstrated that the RIN4 protein1 interacts with the cytoplasmically localized N-terminal portion of NDR1 and that this interaction is required for the activation of resistance signaling following infection by P. syringae expressing the Type III effector protein AvrRpt2. We suggest that this interaction serves to further regulate activation of disease resistance signaling following recognition of Psyringae DC3000-AvrRpt2 by Arabidopsis.

Our current work is focused on defining the molecular events in the RPS2 signaling pathway by employing a combination genetic, biochemical, genomic and cell biological approaches to unravel this complex pathway. This work is supported by NIH.