Key regulator of anther development (e.g. lignification pattern), including tapetum degradation during pollen maturation (e.g. germination capacity). Together with RPK1, required for pattern formation along the radial axis (e.g. the apical embryonic domain cell types that generate cotyledon primordia), and the apical-basal axis (e.g. differentiation of the basal pole during early embryogenesis). ATP + L-seryl-[protein] = ADP + H(+) + O-phospho-L-seryl-[protein] ATP + L-threonyl-[protein] = ADP + H(+) + O-phospho-L-threonyl-[protein] Expressed in root tips, flowers, leaf meristems, and the bottom parts of the surrounding young leaves and trichomes. First detected in the central domain protodermal cells when cotyledon primordia become recognizable, at the early globular stage. Later observed throughout the central domain and basal domain of the embryo proper. After bolting, localized in axillary buds and premature anthers. Abundant in the tapetum of wild-type anthers during microspore maturation. Slightly by dehydration and low temperature. Impaired central domain protoderm patterning defects, and defective cotyledon primordia cell types. Enhanced shoot growth, and male sterility due to defects in anther dehiscence and pollen maturation. Belongs to the protein kinase superfamily. Ser/Thr protein kinase family. Truncated N-terminus.