A CLE11b-CLE16 Signaling Relay Mediates Root-Shoot-Root Crosstalk for Drought Adaptation in Common Bean.

Under soil drought conditions, plant roots sense stress and transmit signals to the shoots, leading to coordinated whole-plant responses to the stress. While several root-to-shoot signals have been identified, the existence and significance of shoot-to-root signals in this process remain unclear. Here, we identify a two-step, CLE peptide-mediated root-shoot-root signaling relay underpinning drought adaptation in common bean. We show that PvCLE16, a gene predominantly expressed in leaves under well-watered conditions, was specifically upregulated in leaves, but not roots, under moderate drought. This spatially restricted transcriptional activation was driven by the leaf-preferentially expressed transcription factor PvTCP10. Accumulated PvCLE16 in leaves promoted stomatal closure and also translocated to the roots, where it suppressed primary root elongation and stimulated lateral root development, adaptations that collectively enhance drought resilience. PvBAM3 was identified as the primary receptor for PvCLE16. Upstream of this module, we found that drought-induced expression of PvCLE16 in leaves requires PvCLE11b, a root-derived CLE peptide that moved acropetally under drought. Together, our findings reveal a novel root-shoot-root signaling relay, wherein root-derived PvCLE11b functions as the upward signal to induce PvCLE16 in leaves, which subsequently acts both locally and systemically by translocating to the roots to coordinate whole-plant drought adaptation responses.