Jasmonic Acid Signalling

Abstract

Jasmonic acid (JA) is an important plant hormone involved in the regulation of plant development and stress responses. A central feature of JA signalling is the repression of JA responses by the JASMONATE ZIM‐DOMAIN (JAZ) protein family. JAZ proteins function to inhibit the activity of transcription factors responsible for driving the expression of JA‐responsive target genes. This is achieved by recruitment of transcriptional repressors and chromatin remodelling proteins. Perception by a COI1‐JAZ coreceptor of the main bioactive molecule in JA signalling, jasmonoyl‐ l ‐isoleucine, results in JAZ protein degradation and release of JA responses from suppression. Specificity in JA signalling is generated by a combination of JAZ protein diversity, cell specificity of JA‐responsive transcription factors and interactions with other plant hormone signalling pathways. Key Concepts (+)‐7‐iso‐jasmonoyl‐ l ‐isoleucine (JA‐Ile) is the main biologically active compound responsible for jasmonic acid (JA) signalling in higher plants. JASMONATE ZIM‐DOMAIN (JAZ) proteins function as the central regulators of jasmonate signalling. JAZ proteins recruit transcriptional repressors to inhibit the activity of transcription factors that positively regulate JA responses. The F‐box protein COI1 functions along with JAZ proteins as a JA‐Ile coreceptor that controls JA‐dependent JAZ protein degradation. Specificity in JA signalling is conferred by context‐specific interactions between JAZ proteins and their targets, and by interactions between JA and other signalling pathways. There are two major pathways for jasmonate‐dependent plant defence responses, which are controlled by antagonistic master‐regulator transcription factors. Herbivores, pathogens and symbiotic microorganisms can manipulate jasmonate signalling for their own benefit. Interactions between JAZ and DELLA proteins mediate trade‐offs between growth and defence. Jasmonates likely function as long‐distance defence signals within, and possibly even between, plants. Other bioactive jasmonates include 12‐oxo‐phytodienoic acid (OPDA) and cis ‐jasmone.