Involved in the regulation of procambium maintenance and polarity during vascular-tissue development (PubMed:17570668). Involved in the pollen tube perception of the female signal (PubMed:26863186). Phosphorylates MDSI1 (PubMed:26863186). ATP + L-seryl-[protein] = ADP + H(+) + O-phospho-L-seryl-[protein] ATP + L-threonyl-[protein] = ADP + H(+) + O-phospho-L-threonyl-[protein] Homodimer. Interacts with MDIS1 and LURE1.2. Expressed in pollen tubes. Autophosphorylation induced by the interaction with LURE1.2. Reduced procambial cells number, and adjacent or interspersed xylem and phloem formation. Belongs to the protein kinase superfamily. Ser/Thr protein kinase family.