The 30th International Conference on Arabidopsis Research (ICAR 2019)

513 / 2019-03-01 12:37:26

A bacterial effector protein prevents MAPK-mediated phosphorylation of SGT1 to suppress plant immunity

MAPK,Ralstonia solanacearum,SGT1,NLR activation,type III effector

Plenary track > Biotic Stress

Plant intracellular nucleotide-binding/leucine-rich repeat (NLR) immune receptors are activated by cognate pathogen effectors, and subsequently trigger host immune responses. The SGT1-RAR1-HSP90 chaperone complex is required to maintain NLR homeostasis and signal transduction, but detailed molecular aspects of the regulation of this chaperone complex for its contribution to effector-triggered immunity (ETI) is unclear. Here we report a Ralstonia solanacearum type III effector, Rip32, which significantly suppresses effector-triggered immunity in Nicotiana benthamiana and Arabidopsis thaliana by specifically targeting SGT1. We found that phosphorylation of SGT1 is correlated with prolonged ETI-triggered MAPK activation, and necessary for effective ETI. We proved that SGT1 associates with multiple MAPKs and Rip32 interferes with the MAPKs-SGT1 interaction to prevent phosphorylation events that are critical for robust NLR activation, resulting in impaired ETI.