Mitogen-activated protein kinases (MAPK) activation post effector recognition in tomato.
A. SHEIKH (1) (1) School of Life Sciences, University of Warwick, United Kingdom

The major virulence strategy of the phytopathogenic bacteria Pseudomonas syringae pv. tomato DC3000 is to secrete effector proteins into the tomato cells to target the immune machinery. AvrPto and AvrPtoB are two such effectors from P. syringae, which disable a range of kinases in tomato. Both effectors target surface-localized receptor-kinases to avoid bacterial recognition. In turn, tomato has evolved an intracellular effector-recognition complex composed of the NB-LRR protein Prf and the Pto kinase. AvrPto is an inhibitor of Pto kinase activity, but paradoxically, this kinase activity is a prerequisite for defense activation by AvrPto. Following P+1 loop disruption and transphosphorylation the Pto/Prf complex dissociate leading to downstream signalling through mitogen-activated protein kinases (MAPKs). Hence, the Pto/Prf complex is a sophisticated molecular trap for effectors and provides an excellent model to study the mechanism of MAPKs activation. In the current study we sought to investigate the mechanism of MAPKs activation post Pto/Prf recognition of AvrPto/AvrPtoB effectors. Tomato 14-3-3 proteins were observed to be part of the signalling complex, which could be specifically targeted by other effectors as well. We also show that an additional P. syringae effector acts act in concert to avert the activation of MAPKs cascade thereby dampening the immune responses.

Abstract Number: P18-691
Session Type: Poster