Extracellular signal peptide that regulates cell fate. Represses root apical meristem maintenance. Mostly expressed in stems and apex, and, to a lower extent, in seedlings, leaves, flowers and siliques. The O-glycosylation (arabinosylation) of the hydroxyproline Pro-97 enhances binding affinity of the CLE22p peptide for its receptor. Belongs to the CLV3/ESR signal peptide family.