Peptide signaling in vascular development

In plants and animals, putative small peptide ligands have been suggested to play crucial roles in development as signal molecules of cell–cell communication. Recent studies of CLAVATA3/ENDOSPERM SURROUNDING REGION (CLE) genes and their products have revealed that distinctive dodeca-CLE peptide ligands function in various developmental processes. In particular, the finding and characterization of TDIF, a dodeca-CLE peptide suppressing tracheary element differentiation, indicates regulation of vascular organization by cell–cell communication through CLE peptides. In addition, other extracellular peptides such as phytosulfokine, proteins such as xylogen, and phytohormones all participate in the ordered formation of vascular tissues.