Delay of Postharvest Browning in Litchi Fruit by Melatonin via the Enhancing of Antioxidative Processes and Oxidation Repair
Delay of Postharvest Browning in Litchi Fruit by Melatonin via the Enhancing of Antioxidative Processes and Oxidation Repair
复制标题
褪黑激素通过增强抗氧化过程和氧化修复来延迟荔枝果实采后褐变
DOI：
10.1021/acs.jafc.8b01922
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发表时间：
2018
影响因子：
6.1
通讯作者：
Zhang Zhengke
中科院分区：
文献类型：
--
作者：
Zhang Yueying;Huber Donald J;Hu Meijiao;Jiang Guoxiang;Gao Zhaoyin;Xu Xiangbin;Jiang Yueming;Zhang Zhengke
褪黑激素是生物体内重要的信号分子和抗氧化分子，具有多种生理功能。为探讨外源褪黑激素对荔枝采后布朗宁的影响及其可能机制，以“紫娘溪”荔枝为试材，用0.4 mM褪黑激素处理后，在25 °C下贮藏8 d。结果表明，褪黑激素能有效抑制贮藏期间果皮的布朗宁，延缓果皮变色。褪黑激素处理降低了相对膜透性，抑制了超氧阴离子自由基（O2-·）、过氧化氢（H2 O2）和丙二醛（MDA）的产生。褪黑激素处理显著促进内源褪黑激素的积累;延迟总酚、类黄酮和花青素的损失;并增强抗氧化酶的活性，包括超氧化物歧化酶（SOD，EC 1.15.1.1）、过氧化氢酶（CAT，EC 1.11.1.6）、抗坏血酸过氧化物酶（APX，EC 1.11.1.11）和谷胱甘肽还原酶（GR，EC 1.6.4.2）。与此相反，与褐变相关的多酚氧化酶（PPO，EC 1.10.3.1）和过氧化物酶（POD，EC 1.11.1.7）活性降低。此外，褪黑激素处理上调了四种编码氧化蛋白修复酶的基因的表达，包括LcMsrA 1，LcMsrA 2，LcMsrB 1和LcMsB 2。这些结果表明，褪黑激素对荔枝果皮布朗宁和衰老的延缓作用可能是通过提高抗氧化能力和调节氧化损伤蛋白的修复来维持氧化还原平衡的结果。
Melatonin acts as a crucial signaling and antioxidant molecule with multiple physiological functions in organisms. To explore effects of exogenous melatonin on postharvest browning and its possible mechanisms in litchi fruit, ‘Ziniangxi’ litchi fruits were treated with an aqueous solution of melatonin at 0.4 mM and then stored at 25 °C for 8 days. The results revealed that melatonin strongly suppressed pericarp browning and delayed discoloration during storage. Melatonin treatment reduced relative membrane-leakage rate and inhibited the generation of superoxide radicals (O2–·), hydrogen peroxide (H2O2), and malondialdehyde (MDA). Melatonin treatment markedly promoted the accumulation of endogenous melatonin; delayed loss of total phenolics, flavonoids, and anthocyanins; and enhanced the activities of antioxidant enzymes, including superoxide dismutase (SOD, EC 1.15.1.1), catalase (CAT, EC 1.11.1.6), ascorbate peroxidase (APX, EC 1.11.1.11), and glutathione reductase (GR, EC 1.6.4.2). By contrast, the activities of browning-related enzymes including polyphenoloxidase (PPO, EC 1.10.3.1) and peroxidase (POD, EC 1.11.1.7) were reduced. In addition, melatonin treatment up-regulated the expression of four genes encoding enzymes for repair of oxidized proteins, includingLcMsrA1,LcMsrA2,LcMsrB1, andLcMsB2. These findings indicate that the delay of pericarp browning and senescence by melatonin in harvested litchi fruit could be attributed to the maintenance of redox homeostasis by the improvement of the antioxidant capacity and modulation of the repair of oxidatively damaged proteins.