Involved in the pollen tube perception of the female signal by binding an unidentified female attractant (PubMed:26863186). May be involved in the regulation of root hairs development (PubMed:16367956). ATP + L-seryl-[protein] = ADP + H(+) + O-phospho-L-seryl-[protein] ATP + L-threonyl-[protein] = ADP + H(+) + O-phospho-L-threonyl-[protein] Expressed in pollen tubes and seedlings. Short straight root hairs. Belongs to the protein kinase superfamily. Ser/Thr protein kinase family.