May play a role in the signal transduction pathway of osmotic stress (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] Expressed specifically in roots. Induced in roots by exposure to air, abscisic acid (ABA) and salt treatment. Belongs to the protein kinase superfamily. Ser/Thr protein kinase family.