College of Horticulture, Sichuan Agricultural University, Chengdu, Sichuan, China.
Institute of Agricultural Resources and Environment, Sichuan Academy of Agricultural Sciences, Chengdu, Sichuan, China.
PLoS One. 2023 Oct 13;18(10):e0292959. doi: 10.1371/journal.pone.0292959. eCollection 2023.
To evaluated the effects melatonin (MT) on the sugar and acid metabolism of early-ripening peach fruits, the concentration of 150 μmol/L MT was sprayed on the leaves of peach trees. MT increased the contents of total soluble sugar and sucrose in peach fruits during the whole ripening period, and increased the contents of glucose and sorbitol at the mature stage. During the whole ripening period, MT also increased the activities of sucrose synthase, sucrose phosphate synthase, neutral invertase, and acidic invertase and the relative expression levels of sucrose synthase, sucrose phosphate synthase, neutral invertase, and acidic invertase genes, while decreased the activity of sorbitol oxidase and the relative expression level of sorbitol dehydrogenase to some extent. Moreover, MT decreased the contents of total organic acid, malic acid, and citric acid at mature stage. At mature stage, MT decreased the activities of citrate synthetase and phosphoenolpyruvate carboxylase and the relative expression levels of citrate synthetase and phosphoenolpyruvate carboxylase genes, while increased the relative expression levels of Nicotinamide adenine dinucleotide phosphate (NADP+)-malic enzyme, malate dehydrogenase, and aconitase genes. Therefore, MT promotes the sugar accumulation and organic acid degradation in early-ripening peach fruits.
为评估褪黑素（MT）对早熟桃果实糖酸代谢的影响，将 150μmol/L MT 浓度喷洒在桃树叶片上。MT 增加了桃果实整个成熟期间总可溶性糖和蔗糖的含量，并增加了葡萄糖和山梨醇在成熟阶段的含量。在整个成熟期间，MT 还增加了蔗糖合酶、蔗糖磷酸合酶、中性转化酶和酸性转化酶的活性以及蔗糖合酶、蔗糖磷酸合酶、中性转化酶和酸性转化酶基因的相对表达水平，而在一定程度上降低了山梨醇氧化酶的活性和山梨醇脱氢酶的相对表达水平。此外，MT 降低了总有机酸、苹果酸和柠檬酸的含量。在成熟阶段，MT 降低了柠檬酸合酶和磷酸烯醇丙酮酸羧激酶的活性以及柠檬酸合酶和磷酸烯醇丙酮酸羧激酶基因的相对表达水平，同时增加了 NADP+-苹果酸酶、苹果酸脱氢酶和乌头酸酶基因的相对表达水平。因此，MT 促进了早熟桃果实中的糖积累和有机酸降解。
