The beneficial roles of melatonin (Mel) and gibberellic acid (GA 3 ) in the biosynthesis of photosynthetic pigments, osmoregulation, and methylglyoxal (MG) detoxification and antioxidant system were studied in tomato ( Solanum lycopersicum L. cv. Five Star) seedlings under NaCl stress. The exogenous application of Mel (100 µM) and GA 3 (1.4 µM) together more efficiently affected growth performance of seedlings under salt stress. The decreased chlorophyll (Chl) degradation and Chl-degrading enzyme (chlorophyllase) activity in seedlings receiving Mel plus GA 3 resulted in increased Chl content by upregulating Chl synthesizing enzyme ( δ -aminolevulinic acid dehydratase) under salinity. Exogenous Mel plus GA 3 suppressed the overproduction of reactive oxygen species (ROS; superoxide and hydrogen peroxide) and activity of glycolate oxidase. Application of Mel with GA 3 reduced MG content by enhancing the activity of enzymes (glyoxalase I and glyoxalase II) involved in the MG detoxification system. Both Mel and GA 3 together protected seedlings from ROS induced damage by regulating Δ 1 -pyrroline-5-carboxylate synthetase activity, and content of proline (Pro) and glycine betaine (GB). Seedlings receiving Mel + GA 3 exhibited a substantial upregulated activity of catalase, ascorbate peroxidase, glutathione reductase, dehydroascorbate reductase, monodehydroascorbate reductase, glutathione peroxidase, polyphenol oxidase and lipoxygenase, and redox homeostasis that reduced oxidative damage induced by salinity. These outcomes advocate that Mel and GA 3 played beneficial roles in Chl, Pro and GB biosynthesis, and improved redox homeostasis, and MG detoxification and antioxidant system under salt stress.

中文翻译：

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褪黑激素和赤霉酸通过调节盐度下番茄幼苗的抗氧化和甲基乙二醛解毒系统促进生长和叶绿素生物合成

褪黑激素 (Mel) 和赤霉酸 (GA 3 ) 在光合色素生物合成、渗透调节、甲基乙二醛 (MG) 解毒和抗氧化系统中的有益作用在 NaCl 下的番茄 ( Solanum lycopersicum L. cv. Five Star) 幼苗中进行了研究压力。Mel (100 µM) 和 GA 3 (1.4 µM) 的外源应用一起更有效地影响盐胁迫下幼苗的生长性能。接受 Mel 加 GA 3 的幼苗中叶绿素 (Chl) 降解和 Chl 降解酶 (叶绿素酶) 活性降低，通过在盐度下上调 Chl 合成酶 (δ-氨基乙酰丙酸脱水酶) 导致 Chl 含量增加。外源性 Mel 加 GA 3 抑制了活性氧（ROS；超氧化物和过氧化氢）的过量产生和乙醇酸氧化酶的活性。Mel 与 GA 3 的应用通过增强参与 MG 解毒系统的酶（乙二醛酶 I 和乙二醛酶 II）的活性来降低 MG 含量。Mel 和 GA 3 通过调节 Δ 1 -pyrroline-5-carboxylate 合成酶活性以及脯氨酸 (Pro) 和甘氨酸甜菜碱 (GB) 的含量共同保护幼苗免受 ROS 诱导的损伤。接受 Mel + GA 3 的幼苗表现出显着上调的过氧化氢酶、抗坏血酸过氧化物酶、谷胱甘肽还原酶、脱氢抗坏血酸还原酶、单脱氢抗坏血酸还原酶、谷胱甘肽过氧化物酶、多酚氧化酶和脂肪氧合酶以及氧化还原稳态的活性，这些活性降低了由盐分诱导的氧化损伤。这些结果主张 Mel 和 GA 3 在 Chl、Pro 和 GB 生物合成中发挥有益作用，并改善氧化还原稳态，