Regulates planar ovule integument development. ATP + L-seryl-[protein] = ADP + H(+) + O-phospho-L-seryl-[protein] ATP + L-threonyl-[protein] = ADP + H(+) + O-phospho-L-threonyl-[protein] Expressed in the epidermis and cortex of the transition zone of the root apex. Expressed in rosette leaves, stems, flowers and siliques. No visible phenotype under normal growth conditions, but the double mutants ucn-2 and ucnl-5 are embryonic lethal. Belongs to the protein kinase superfamily. AGC Ser/Thr protein kinase family.