Advances in the chemical biology of jasmonates

Plant oxylipins include the jasmonates, lipid-derived hormones that control growth-defense trade-offs. In tracheophytes, (3R, 7S)-jasmonoyl-L-isoleucine (JA-Ile) is the principal bioactive ligand that assembles the COI1-JAZ co-receptor together with inositol polyphosphates, leading to JAZ degradation and transcriptional reprogramming. By contrast, bryophytes employ dn-cis/iso-OPDA and related species, revealing evolutionary diversity in ligand identity and receptor matching. This review synthesizes chemical perspectives on jasmonate signaling. First, we outline the "molecular-glue" logic of COI1-JAZ assembly and the current structural gap beyond Arabidopsis that limits lineage-level, structure-guided discussion. Second, we summarize multilayered metabolic circuits that sculpt signal intensity, duration and spatial distribution: oxidation of JA-Ile to 12-OH- and 12-COOH-JA-Ile; hydrolysis; and hydroxylation of the JA backbone. Notably, 12-OH-JA-Ile can function as a weak and "biased" agonist, whereas 12-COOH-JA-Ile is receptor-silent; in Marchantia, dn-iso-OPDA is chiefly inactivated by conjugation with amino acids, paralleling auxin logic. Third, we review evidence for co-evolution of ligands with COI1/JAZ components across land plants. Finally, we highlight the design of COI1-JAZ subtype-selective agonists and antagonists-often based on coronatine scaffolds-that preferentially recruit specific JAZ proteins to promote ERF/ORA outputs while sparing MYC-branch responses. These chemical levers suggest practical routes to amplify defense with reduced growth costs, offering opportunities for stress-resilient crop improvement.