Involved in chitin-triggered immune signaling and is required for reactive oxygen species (ROS) production (PubMed:29907700). Acts downstream of SD129 in defense signaling triggered by the pathogen-associated molecular pattern (PAMP) 3-OH-C10:0, a medium-chain 3-hydroxy fatty acid (PubMed:31922267). ATP + L-seryl-[protein] = ADP + H(+) + O-phospho-L-seryl-[protein] ATP + L-threonyl-[protein] = ADP + H(+) + O-phospho-L-threonyl-[protein] Interacts with the Xanthomonas campestris effector XopAC/AvrAC (PubMed:23951354). Interacts with SD129 (PubMed:31922267). Phosphorylated by SD129 at Thr-306 and Thr-310 in response to the pathogen-associated molecular pattern (PAMP) 3-OH-C10:0, a medium-chain 3-hydroxy fatty acid. Belongs to the protein kinase superfamily. Ser/Thr protein kinase family. It is uncertain whether Met-1 or Met-55 is the initiator.