LAUSR

Deciding whether to grow or to divert energy to stress responses is a major physiological trade-off for plants surviving in fluctuating environments. We show that three leucine-rich repeat receptor kinases (LRR-RKs) act as direct ligand-perceiving receptors for PLANT PEPTIDE CONTAINING SULFATED TYROSINE (PSY)-family peptides and mediate switching between two opposing pathways. By contrast to known LRR-RKs, which activate signaling upon ligand binding, PSY receptors (PSYRs) activate the expression of various genes encoding stress response transcription factors upon depletion of the ligands. Loss of PSYRs results in defects in plant tolerance to both biotic and abiotic stresses. This ligand-deprivation–dependent activation system potentially enables plants to exert tuned regulation of stress responses in the tissues proximal to metabolically dysfunctional damaged sites where ligand production is impaired. Description Balancing growth and stress responses A collection of small, sulfated peptides act as growth-promoting hormones in the model plant Arabidopsis thaliana. Ogawa-Ohnishi et al. characterized the structures of several of these PLANT PEPTIDE CONTAINING SULFATED TYROSINE (PSY) family peptides and identified their receptors among subfamily XI of the Arabidopsis leucine-rich repeat receptor kinases (LRR-RKs). These functionally redundant receptors repress plant growth and activate stress-response genes when they are not repressed by their peptide hormone ligands. From this branched signaling point, plant cells deprived of their sustaining signal as they face abiotic or biotic stress can divert resources from growth to stress responses. —PJH A ligand deprivation–dependent activation system helps plants tune stress responses near damaged sites.