CLE peptides (CLAVATA3/ESR-related peptides) are a family of small, secreted signaling peptides found in plants. They play critical roles in regulating various aspects of plant development, including stem cell maintenance in meristems, organ formation, vascular development, and response to environmental stimuli. The name "CLE" is derived from two key members: CLAVATA3 (CLV3) from Arabidopsis thaliana and ESR (Embryo Surrounding Region) proteins from maize.
CLE peptides are typically 12 to 13 amino acids long and are derived from larger precursor proteins that contain a conserved CLE domain near the C-terminus. These precursor proteins are processed post-translationally to release the active peptide. Once secreted, CLE peptides bind to leucine-rich repeat receptor-like kinases (LRR-RLKs) on the surface of target cells, initiating intracellular signaling cascades that modulate gene expression and cellular activity.
One of the most well-studied functions of CLE peptides is their role in the CLV3-WUSCHEL (WUS) feedback loop in the shoot apical meristem, where CLV3 signaling restricts the expression of WUS, a transcription factor essential for stem cell identity. This interaction maintains the balance between stem cell proliferation and differentiation.
CLE genes have been identified in a wide range of plant species, including angiosperms, gymnosperms, and bryophytes, suggesting evolutionary conservation of their functions. Additionally, some plant-parasitic nematodes produce CLE-like peptides that mimic host signaling molecules, subverting plant development to form feeding sites.
Research on CLE peptides contributes to understanding plant growth regulation and has potential applications in agriculture, such as modifying plant architecture or improving stress responses.