RALFs Peptide regulators of plant growth

Peptide signaling regulates a variety of developmental processes and environmental responses in plants.(1-6) For example, the peptide systemin induces the systemic defense response in tomato(7) and defensins are small cysteine-rich proteins that are involved in the innate immune system of plants.(8,9) The CLAVATA(3) peptide regulates meristem size(10) and the SCR peptide is the pollen self-incompatibility recognition factor in the Brassicaceae.(11,12) LURE peptides produced by synergid cells attract pollen tubes to the embryo sac.(9) RALFs are a recently discovered family of plant peptides that play a role in plant cell growth.