Plant Peptide Signals

Over the past 25 years, knowledge of plant peptide signalling has expanded and recent discoveries have allowed us to understand several mecha- nisms underpinning their action. It is becoming clear that cell–cell communication mediated by peptide signalling is integral to many plant pro- cesses. This article focusses on the best-studied areas of plant peptide signalling. We discuss two major families of plant peptides that function dur- ing plant development; the CLAVATA3/endosperm surrounding region (CLE) peptide family, which regulate cell differentiation and division at the shoot apical meristem (SAM), root apical meristem (RAM) and in the vasculature and the epidermal patterning factor-like (EPFL) family of signalling peptides that regulate stomatal development and patterning. We also discuss peptides that regulate self-incompatibility, and the role of the peptide phytosulfokine during plant growth, pollen tube growth and guidance and pathogen infection.