Component of the abscisic acid (ABA) signaling pathway that may act as ABA signal transducer in the context of abiotic stresses. Triggers MPK7 activation in a MKK3-dependent manner. Mediates the ABA-dependent activation of the MKK3-MPK7 module. ATP + L-seryl-[protein] = ADP + H(+) + O-phospho-L-seryl-[protein] ATP + L-threonyl-[protein] = ADP + H(+) + O-phospho-L-threonyl-[protein] Binds to MKK3. Strongly induced by abscisic acid (ABA). Accumulates in response to osmotic stresses (e.g. mannitol and NaCl). In the double mutant map3k17 map3k18, impaired MPK7 activation mediated by abscisic acid (ABA). Belongs to the protein kinase superfamily. Ser/Thr protein kinase family.