Peptide prevents water loss from thirsty leaves

Plant roots sense water shortages and must convey this message to the rest of the plant. In response to such dehydration signals, the hormone abscisic acid (ABA) accumulates in plant leaves where it regulates stomatal movement to prevent water loss by transpiration. In search of the molecule that conveys the root-to-shoot signal under water-deficient conditions, Fuminori Takahashi and colleagues identified a peptide called CLE25. They report that, in response to dehydration stress, this molecule moves from the roots through the vasculature to the plant shoots, where it binds to the BAM receptor to modulate ABA expression and so stomatal closure.