ATP + L-seryl-[protein] = ADP + H(+) + O-phospho-L-seryl-[protein] ATP + L-threonyl-[protein] = ADP + H(+) + O-phospho-L-threonyl-[protein] Detected in root, stem, leaf and flower. By salicylic acid (SA), by a bacterial pathogen infection or by oxidative stress. May be regulated by WRKY DNA-binding proteins at the transcriptional level. Belongs to the protein kinase superfamily. Ser/Thr protein kinase family. CRK subfamily.