RPK2 functions in diverged CLE signaling.

Shoot apical meristem is a well organized undifferentiated tissue which produces plant body. CLV3 peptide hormone regulates SAM homeostasis, and is perceived by several receptor complexes, CLV1, CLV2-SOL2/CRN, and RPK2. CLV1 homologues are encoded in various plants genome. However CLV2 and SOL2/CRN homologues are found only in higher plants. Here we show that the RPK2 homologues were found not only in moss, Physcomitrella patens, but also in liverwort, Marchantia polymorpha. Although CLV2-SOL2/CRN might have specific function in SAM homeostasis, CLV1 and RPK2 may regulate various plant physiological events during plant evolution.