Abstract Melatonin (MT) functions as an important bio-active molecule in diverse physiological processes in higher plants. In the present study the role of MT in modulating ripening and softening in relation to ethylene and abscisic acid (ABA) biosyntheses in stored mango fruit was evaluated. The results showed that application of MT (0.5 mM, immersion for 1 h) to ‘Guifei’ mangoes effectively delayed the changes in ripening parameters including firmness, pulp color, β-carotene levels, soluble solids content (SSC), titratable acidity (TA) and respiration rate. MT markedly delayed climacteric ethylene production and 1-aminocyclopropane-1-carboxylic acid (ACC) levels in mango fruit during storage, likely a consequence of reduced activities of ACC synthase (ACS) and ACC oxidase (ACO). MT treatment resulted in delayed accumulation of ABA through reducing activity of a key ABA biosynthetic enzyme (9-cis-epoxycarotenoid dioxygenase, NCED). MT treatment suppressed the changes in activities of pectin-modifying enzymes including polygalacturonase (PG), β-galactosidase (β-Gal) and pectin methylesterase (PME), and limited the solubilization and depolymerization of pectin polysaccharides. The results indicate that MT could be involved in modulation of ripening and softening in mango fruit through inhibiting the biosyntheses of ethylene and ABA.

中文翻译：

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采后施用褪黑激素延缓'贵妃'芒果果实成熟软化

摘要 褪黑激素（MT）在高等植物的多种生理过程中作为一种重要的生物活性分子发挥作用。在本研究中，评估了 MT 在调节成熟和软化与储存芒果果实中乙烯和脱落酸 (ABA) 生物合成相关的作用。结果表明，MT（0.5 mM，浸泡 1 h）对“贵妃”芒果有效延迟了成熟参数的变化，包括硬度、果肉颜色、β-胡萝卜素水平、可溶性固形物含量（SSC）、可滴定酸度（TA ) 和呼吸频率。MT 显着延迟芒果果实在储藏过程中的更年期乙烯生成和 1-氨基环丙烷-1-羧酸 (ACC) 水平，这可能是 ACC 合酶 (ACS) 和 ACC 氧化酶 (ACO) 活性降低的结果。MT 处理通过降低关键 ABA 生物合成酶（9-顺式-环氧类胡萝卜素双加氧酶，NCED）的活性导致 ABA 的延迟积累。MT 处理抑制了果胶修饰酶的活性变化，包括聚半乳糖醛酸酶 (PG)、β-半乳糖苷酶 (β-Gal) 和果胶甲酯酶 (PME)，并限制了果胶多糖的增溶和解聚。结果表明，MT可能通过抑制乙烯和ABA的生物合成参与调控芒果果实的成熟和软化。并限制了果胶多糖的增溶和解聚作用。结果表明，MT可能通过抑制乙烯和ABA的生物合成参与调控芒果果实的成熟和软化。并限制了果胶多糖的增溶和解聚作用。结果表明，MT可能通过抑制乙烯和ABA的生物合成参与调控芒果果实的成熟和软化。