DELLAs Modulate Jasmonate Signaling via Competitive Binding to JAZs

SummaryGibberellins (GAs) modulate jasmonate (JA) signaling, which is essential for stress response and development in plants. However, the molecular details of such phytohormone interaction remain largely unknown. Here, we show that the JA ZIM-domain 1 (JAZ1) protein, a key repressor of JA signaling, interacts in vivo with DELLA proteins, repressors of the GA pathway. DELLAs prevent inhibitory JAZ1 interaction with a key transcriptional activator of JA responses, MYC2, and, thus, enhance the ability of MYC2 to regulate its target genes. Conversely, GA triggers degradation of DELLAs, which allows JAZ1 to bind MYC2 and suppress MYC2-dependent JA-signaling outputs. Therefore, our results reveal one means by which GAs suppress cellular competence to respond to JA. Because DELLAs serve as central regulators that mediate the crosstalk of various phytohormones, our model also suggests a candidate mechanism by which JA signaling may be fine-tuned by other signaling pathways through DELLAs.

Graphical AbstractFigure optionsDownload high-quality image (161 K)Download as PowerPoint slideHighlights
► Gibberellins (GAs) inhibit DELLA-mediated upregulation of jasmonate (JA) target genes
► DELLAs compete the JA signaling repressor JAZ1 away from the JA effector MYC2
► DELLA/JAZ binding derepresses MYC2's ability to regulate JA-responsive genes
► DELLAs promote cellular competence to respond to JA