https://emsenn.net/tags/fruitripening/ Recent content in FruitRipening on emsenn.net Hugo en-us Thu, 02 Apr 2026 00:00:00 +0000 https://emsenn.net/library/domains/science/domains/biology/domains/botany/terms/ethylene/ Thu, 02 Apr 2026 00:00:00 +0000 https://emsenn.net/library/domains/science/domains/biology/domains/botany/terms/ethylene/ <p>Ethylene: the only gaseous plant hormone (C₂H₄), diffusing freely through air and soil to regulate fruit ripening, senescence, leaf and flower abscission, defense responses, and the &ldquo;triple response&rdquo; in dark-grown seedlings. Operating at nanomolar concentrations, ethylene is produced in response to stress, wounding, and fruit maturation, coordinating plant responses across multiple tissues simultaneously.</p> <h2 id="biosynthesis">Biosynthesis</h2> <p>Ethylene is synthesized through the Yang cycle: methionine → S-adenosylmethionine (SAM, via SAM synthetase) → 1-aminocyclopropane-1-carboxylic acid (ACC, via ACC synthase / ACS) → ethylene (via ACC oxidase / ACO). ACS is the rate-limiting enzyme; it is encoded by a multigene family and regulated at both transcriptional and post-translational levels. Phosphorylation by MAP kinases (MPK3/MPK6) stabilizes certain ACS isoforms. ACC can also be conjugated to malonyl-ACC or gamma-glutamyl-ACC as a storage form, sequestering the hormone and rendering it inactive until deconjugation is needed.</p>