Forms a complex with CRK36 that may negatively control abscisic acid (ABA) and osmotic stress signal transduction (PubMed:22225700). Involved in plant response to ABA during seed germination, early seedling growth and responses to abiotic stresses by inducing the expression of ABA-responsive genes and stress-inducible genes (PubMed:23583936). Acts as positive regulator in disease resistance, downstream of NPR1 and WRKY70 (PubMed:24215930). ATP + L-seryl-[protein] = ADP + H(+) + O-phospho-L-seryl-[protein] ATP + L-threonyl-[protein] = ADP + H(+) + O-phospho-L-threonyl-[protein] Interacts with CRK36. Interacts with CRK36 at the cell surface. By ozone. Down-regulated by light stress (PubMed:20500828). Induced by infection with Hyaloperonospora arabidopsidis (PubMed:21711359). Induced by salt stress, drought stress and abscisic acid (ABA) (PubMed:22225700). Induced by salicylic acid (SA) and infection with the bacterial pathogen P.syringae and the necrotrophic fungal pathogen B.cinerea (PubMed:24215930). Autophosphorylated and phosphorylated by CRK36. No visible phenotype under normal growth conditions, but mutant seedlings show increased sensitivity to abscisic acid (ABA) and salt stress during post-germinative growth (PubMed:22225700). Increased susceptibility to P.syringae infection. Weak expression of pathogenesis-related (PR) genes after infection with P.syringae or salicylic acid (SA) treatment (PubMed:24215930). May be due to a competing acceptor splice site. Belongs to the protein kinase superfamily. Ser/Thr protein kinase family. CRK subfamily.