May play a role in the regulation of plant growth and development (Probable). May be involved in plant defense signaling (By similarity). ATP + L-seryl-[protein] = ADP + H(+) + O-phospho-L-seryl-[protein] ATP + L-threonyl-[protein] = ADP + H(+) + O-phospho-L-threonyl-[protein] Roots, leaves and stems. Belongs to the protein kinase superfamily. Ser/Thr protein kinase family.