Plasma Membrane Proteome Profiling During Activation Of Plant Innate Immunity

Plants can be infected by diverse pathogens and, in order to survive, plants must defend themselves from these attacks. Plants possess an innate immune system that is capable of recognizing conserved pathogen features on the cell-surface using extracellular receptors or pathogen effectors delivered inside host cells using intracellular receptors. Immune receptor activation leads to defense responses and disease resistance. The plant plasma membrane (PM) mediates critical aspects of plant innate immunity including pathogen perception, signaling, and downstream activation of defense responses. In order to understand the dynamics of PM proteins during plant innate immunity, we have analyzed the Arabidopsis PM proteome after activation of the extracellular flagellin receptor FLS2 and the intracellular resistance protein RPS2. Dynamic changes in PM protein abundance were detected using gel-enhanced liquid chromatography tandem mass spectrometry coupled with spectral counting. We were able to quantify over 1,000 proteins across multiple biological replications, revealing distinct as well as overlapping sets of differential expression upon activation of the FLS2 and RPS2 immune receptors. Many of these membrane proteins are known to be involved in plant defense. For instance, over 20% of up-regulated proteins during RPS2 activation have known roles in plant immune responses. Arabidopsis T-DNA knockouts for differentially regulated proteins were screened for altered disease phenotypes to the bacterial pathogen Pseudomonas syringae pv. tomato. Network analyses of PM proteins differentially expressed during innate immunity as well as biological data for select candidate genes will be presented