jasmonatemediated

Jasmonate-mediated signaling refers to plant hormonal responses governed by jasmonates, especially jasmonic acid (JA) and its bioactive conjugate jasmonoyl isoleucine (JA-Ile). This pathway coordinates defense against herbivores and pathogens and modulates growth and development in flowering plants.

Biosynthesis of jasmonates occurs via the octadecanoid pathway, starting from linolenic acid through lipoxygenase (LOX), allene oxide synthase (AOS), and allene oxide cyclase (AOC) to produce OPDA, which is reduced and beta-oxidized to JA. JAR1 then conjugates JA to isoleucine to form JA-Ile, the primary bioactive ligand recognized by the signaling module.

Perception and signaling rely on the COI1 receptor as part of the SCFCOI1 E3 ubiquitin ligase complex. JA-Ile binding promotes ubiquitination and proteasomal degradation of JAZ repressor proteins, releasing transcription factors such as MYC2 and related proteins to activate JA-responsive genes. This cascade induces production of protease inhibitors, alkaloids, and other defensive metabolites, and interacts with ethylene signaling through factors like ORA59 and ERF1 to regulate a broader defense transcriptome.

Biological roles of jasmonate signaling include defense against chewing insects and necrotrophic pathogens, wound repair, and modulation of development, including trichome formation, seed and pollen biology, and senescence. The pathway also participates in systemic defense signaling, enabling distal responses within the plant.

Methyl jasmonate (MeJA) acts as a volatile signal to prime defenses in neighboring plants. Cross-talk with salicylic acid, ethylene, and abscisic acid pathways yields context-dependent antagonism or synergy, shaping outcomes in plant immunity and growth. Research often focuses on components such as coi1, jar1, and various JAZ repressors to dissect pathway dynamics.