Component of the abscisic acid (ABA) signaling pathway that acts as ABA signal transducer in the context of abiotic stresses (PubMed:26443375, PubMed:25720833, PubMed:25680457). Triggers MPK1, MPK2, MPK7 and MPK14 activation in a MKK3-dependent manner and MPK6 activation in a MKK3-independent manner. Mediates the ABA-dependent activation of the MKK3-MPK7 module (PubMed:25720833). Positive regulator of ABA responses leading to the induction of gene expression (e.g. RD29B and RAB18) and involved in various responses including stomatal development, stomatal movement, inhibition of germination and root growth (PubMed:26443375). Promotes leaf senescence (PubMed:25680457). ATP + L-seryl-[protein] = ADP + H(+) + O-phospho-L-seryl-[protein] ATP + L-threonyl-[protein] = ADP + H(+) + O-phospho-L-threonyl-[protein] Kinase activity is activated by abscisic acid (ABA) (PubMed:26443375, PubMed:25680457). Inhibited by ABI1. Activated by SRK2E (PubMed:26443375). Interacts with ABI1 (PubMed:26443375). Binds to MKK3 (PubMed:25720833, PubMed:25680457). Associates with SRK2E within the nucleus (PubMed:26852793). Expressed in roots, leaves and flowers. In developing flowers, observed in sepals, anther filaments, ovaries and meristem tissues. Also expressed in root meristem tissues and in areas of lateral root formation. In leaves, detected in guard cells and trichomes. Strongly induced by abscisic acid (ABA) in the flowers, leaves and root tissues (PubMed:26443375, PubMed:25720833). Accumulates in response to osmotic stresses (e.g. mannitol and NaCl) (PubMed:25720833). Autophosphorylated. Unstable protein degraded by the proteasome pathway; this degradation is promoted by ABI1, but blocked by ABA. More vigorous root growth, decreased abaxial stomatal index and increased stomatal aperture. Reduced induction of RD29B and RAB18 expression in response to treatment with abscisic acid (ABA) (PubMed:26443375). In the double mutant map3k17 map3k18, impaired MPK7 activation mediated by ABA (PubMed:25720833). Belongs to the protein kinase superfamily. Ser/Thr protein kinase family.