Extracellular signal peptide secreted by differentiated root cells that regulates root cell fate. Acts with ACR4 as a ligand-receptor pair in a signal transduction pathway, coordinating movement of the root tip and organization of cell divisions in the root meristem. Promotes cell differentiation in the distal root meristem in a dose-dependent manner, especially the transition from columella stem cells (CSC) daughters into columella cells (CCs). Induces ACR4 expression in root quiescent center (QC). Involved in WUX5 QC-specific expression pattern regulation. Regulates the transition of protophloem cells from proliferation to differentiation, thus impinging on postembryonic growth capacity of the root meristem; this signaling pathway requires CRN and CLV2 (PubMed:28607033). Mostly expressed at low levels in stems and apex, and, to a lower extent, in roots, seedlings, leaves, flowers, siliques and pollen. Expressed in the entire embryo at the globular stage. Progressively restricted to the basal regions of the embryo that form the root meristem and the vasculature. After germination, detected in the differentiation zone of the stele that forms the inner layers of the root and in differentiating columella cells (CCs). Short roots with irregularly shaped root tips and following a waving pattern. Delayed differentiation of columella stem cells (CSC) daughters into columella cells (CCs). Belongs to the CLV3/ESR signal peptide family.