Regulates planar ovule integument development by suppressing aberrantly oriented growth. Maintains planar growth of integuments by repressing the developmental regulator and transcription factor KAN4 which is involved in the control of early integument growth and polarity. Restricts growth in stamen filaments, petals, and cotyledons. 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 and developing flowers. Expressed in rosette leaves, stems and siliques. Ectopic growth in filaments and petals, distortion of integument planar growth and aberrant embryogenesis and partial lethality in ucn-1 embryos. The double mutants ucn-2 and ucnl-5 are embryonic lethal. Belongs to the protein kinase superfamily. AGC Ser/Thr protein kinase family.