Phosphoproteomic profiling reveals early regulatory mechanisms of membrane-associated proteins during ETI
T. LIEBRAND (1), D. Matuszak (1), G. Coaker (1) (1) UC Davis, Dept. of Plant Pathology, U.S.A.

Pattern-Triggered Immunity (PTI) and Effector-Triggered Immunity (ETI) are believed activate similar defense signaling pathways in plants, but ETI is considered to be a faster and stronger response. Plant immune signaling networks have primarily been generated from gene expression and yeast two-hybrid datasets. Recently, phosphoproteomic screens revealed protein regulatory mechanisms during the early stages of PTI. Here, we used differential phosphoproteomic profiling and protein expression analysis on Arabidopsis thaliana membrane fractions mounting ETI mediated by the NLR RPS2. RPS2 mediates resistance to strains of Pseudomonas syringae secreting the AvrRpt2 protease effector. Arabidopsis plants expressing dexamethasone (dex)-inducible AvrRpt2 were tissue harvested for analysis 0, 1 and 3 hours post dex spray. As a control we harvested tissue from an Arabidopsis mutant line expressing AvrRpt2 in a susceptible genetic background. We identified over 300 significantly differentially regulated phosphorylation sites. Several of these phosphorylation events are known to be required for PTI, thus revealing overlap between early signaling events during PTI and ETI. We identified enhanced phosphorylation of immune related kinases, calcium binding proteins, water channels, and protein(s) involved in regulating the reactive oxygen species burst. Mutant lines for several of these genes exhibit altered defense-related phenotypes. The role of select phosphorylated proteins during plant immune signaling will be presented.

Abstract Number: P17-559
Session Type: Poster