Involved in disease resistance and abiotic stress tolerance signaling pathways. Acts as a positive regulator of drought, salt and cold tolerance. Negatively modulates pathogenesis-related (PR) gene expression and broad-spectrum disease resistance (PubMed:12615946). Functions downstream of CPK18 in a signaling pathway that represses defense gene expression and negatively regulates resistance to rice blast fungus. Phosphorylated by CPK18 at Thr-14 and Thr-32 and activated independently of MAP kinase kinase (MKK) phosphorylation (PubMed:25035404). ATP + L-seryl-[protein] = ADP + H(+) + O-phospho-L-seryl-[protein] ATP + L-threonyl-[protein] = ADP + H(+) + O-phospho-L-threonyl-[protein] Activated by threonine and tyrosine phosphorylation (By similarity). Activated in response to low temperature (12 degrees Celsius) treatment (PubMed:12177502, PubMed:12615946). Activated by phosphorylation at Thr-14 and Thr-32 by CPK18 (PubMed:25035404). Interacts with MKK1 (PubMed:12177502). Interacts with CPK18 (PubMed:25035404). Expressed in roots, stems and panicles, and at lower levels in leaves. By benzothiadiazole (BTH), dichloroisonicotinic acid, probenazole, jasmonic acid, wounding and infection with P.syringae and M.grisea, by stresses, hormones, heavy metals, high/low temperature, UV-C and phosphatase inhibitors. The TXY motif contains the threonine and tyrosine residues whose phosphorylation activates the MAP kinases. Dually phosphorylated at Thr-194 and Tyr-196, which activates the enzyme (By similarity). Autophosphorylated. Phosphorylated by CPK18 at Thr-14 and Thr-32, which activates the enzyme (PubMed:25035404). Does not possess kinase activity. Belongs to the protein kinase superfamily. CMGC Ser/Thr protein kinase family. MAP kinase subfamily. Truncated N-terminus.