Plants have developed particularly sophisticated signaling pathways to orchestrate cellular responses upon detecting potential danger signals. In Arabidopsis thaliana, the three-tiered MAPK kinase kinase (MKKK)–MAPK kinase (MKK)–MAPK cascades respond to signals from receptors that recognize diverse stimuli, activating plant immunity. At the cell surface, pattern recognition receptor (PRR) complexes detect microbe-associated molecular patterns (MAMPs) and host-derived damage-associated molecular patterns (DAMPs). Concurrently, intracellular nucleotide-binding leucine-rich-repeat receptors (NLRs) perceive microbial effectors secreted into plant cells and can subsequently form resistosomes, functioning as Ca²⁺-permeable channels.

While most studies focus on individual proteins regulated by the MAPK cascade that play prominent roles in plant innate immunity, proteome-wide investigations have been limited due to challenges in handling kinase variant mutants. In this study, we utilize chemically perturbed mapk mutants to map phospho-proteomes following elicitor perception. Arabidopsis seedlings treated with flagellin peptide will be analyzed for total protein phosphorylation across different time points, with varying concentrations of a MAPK inhibitor. Results from this study will provide insight into the temporal dynamics of protein modification in plant immune responses and reveal novel immune players.