May be involved in plant defense signaling. 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. Predominantly localized at the plasma membrane. Strongly expressed in leaves, moderately in flowers, and barely in roots. Belongs to the protein kinase superfamily. Ser/Thr protein kinase family.