Practice question

CLAVATA3 encodes small secreted CLE peptide family ligand predominantly produced in central zone stem cells of shoot apical meristem, processed into twelve amino acid arabinosylated mature peptide with hydroxylated prolines. It diffuses apoplastically into organizing center where leucine-rich repeat receptor kinases CLV1 homodimer and CLV2-CORYNE heterodimer perceive it activating downstream POLTERGEIST phosphatase and MAPK signaling to repress WUS transcription. This short-range paracrine signal limits WUS domain and stem cell number preventing overproliferation while preserving reservoir required for organ initiation, exemplifying peptide-mediated homeostasis essential for meristem size control.