Extracellular signaling peptide that may regulate primary root growth rate and systemic nitrogen (N)-demand signaling (By similarity). Mediates up-regulation of genes involved in N uptake and assimilation pathways (PubMed:25324386). Interacts with CEP receptors (e.g. CEPR1 and CEPR2). Accumulates in xylem sap. Expressed in lateral root primordia and in lateral roots excluding the meristem region. The mature small signaling peptide is generated by proteolytic processing of the longer precursor. Belongs to the C-terminally encoded plant signaling peptide (CEP) family.