Abstract
Pathogen recognition triggers Mitogen Activated Protein Kinase (MAPKs) activation, which coordinates external cues to changes in plant gene expression. Given the robust subcellular localization of MAPKs, we focused on the chromatin phosphoproteomics of WT and mpk3, mpk4, and mpk6 mutant plants. A number of novel nuclear targets were identified for MPK3, MPK4 and/or MPK6. These targets include key regulatory proteins of cell division, development and immunity. Out of the targets, 165 proteins were identified to be differentially phosphorylated after Microbe Associated Molecular Pattern (MAMP) treatment. Using different criteria, a number of MAPK substrates were validated as true substrates of MAPKs. Signaling network analysis revealed their potential role in general cellular processes like RNA metabolism, transcription and chromatin organization, and also specific roles in immunity. Overall, this study unravels a set of chromatin-associated targets of MAPKs and a potential link between MAPK signaling to a number of chromatin-related events.