Protein kinase required for plant defense mechanism mediated by the disease resistance (R) protein RPS5. In case of infection by Pseudomonas syringae, AvrPphB triggers RPS5-mediated defense mechanism via the cleavage of PBS1. Both kinase activity and cleavage by avrPphB are independently required to trigger the RPS5-mediated resistance. Contributes to PAMP-triggered immunity (PTI) signaling and defense responses downstream of FLS2. ATP + L-seryl-[protein] = ADP + H(+) + O-phospho-L-seryl-[protein] ATP + L-threonyl-[protein] = ADP + H(+) + O-phospho-L-threonyl-[protein] In infected plant cells, it interacts with the P.syringae virulence protein avrPphB. In uninfected plants, autophosphorylated form interacts with RPS5. Interacts with FLS2. Induced by flagellin (flg22). Cleaved by avrPphB in infected plant cells. Its cleavage serves as a signal that triggers the RPS5-mediated defense system. Autophosphorylates (Probable). Autophosphorylation may be required to trigger the RPS5-mediated plant defense system. Palmitoylation at Cys-3 and Cys-6 are required for plasma membrane location that is essential for the RPS5-mediated plant defense response. Reduction in H(2)O(2) accumulation and callose deposits. Belongs to the protein kinase superfamily. Ser/Thr protein kinase family.