A Small Peptide Signal Regulates Systemic Responses to Plant Water Status ($)

Plant organs perceive their immediate environment and communicate over both short and long distances to regulate the physiology of the affected organ as well as organs distal to the perceived stress. To accomplish this, plants utilize an impressive array of signalling molecules which range from small chemical signatures to macromolecules such as proteins and RNA. In a recent Letter to Nature, Takahashi et al. demonstrate that systemic responses to water deficit are regulated by the long distance movement of the small signalling peptide CLE25 in Arabidopsis thaliana. The authors demonstrate the accumulation and long-distance movement of the CLE25 peptide hormone from roots to shoots in drought stressed plants, where CLE25 was shown to modulate stomatal aperture to conserve water. This activity was dependent on the presence functional BAM (BARELY ANY MERISTEM) receptor proteins, which argues for the presence of a systemic CLE25-BAM signalling module that is essential for aboveground responses to dehydration. (Summary by Philip Carella) Nature 10.1038/s41586-018-0009-2