Melatonin Enhances Cold Tolerance by Regulating Energy and Proline Metabolism in Litchi Fruit
Melatonin Enhances Cold Tolerance by Regulating Energy and Proline Metabolism in Litchi Fruit
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褪黑素通过调节荔枝果实能量和脯氨酸代谢增强耐寒性
DOI：
10.3390/foods9040454
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发表时间：
2020-04-01
期刊：
影响因子：
5.2
通讯作者：
Zhang, Zhengke
中科院分区：
文献类型：
--
作者：
Liu, Gangshuai;Zhang, Yuxin;Zhang, Zhengke
褪黑激素（MLT）是调节高等植物多种生理过程的重要信号分子。在本研究中，研究了MLT在调节荔枝果实耐冷性中的作用及其可能的机制。结果表明，‘白糖营’荔枝果实施用 MLT（400 μM，浸渍 20 分钟）可有效延缓冷害（CI）的发展，同时抑制果皮变色，较高的色度值（L*、a*、b*）和花青素水平表明。 MLT 处理抑制了相对电导率 (REC) 和丙二醛 (MDA) 含量的增加，这可能有助于维持荔枝果实膜的完整性。 MLT 治疗减缓了细胞能量水平的下降，三磷酸腺苷 (ATP) 含量和能量电荷 (EC) 较高证明了这一点，这可能归因于与能量代谢相关的酶活性增加，包括 H+-ATP 酶、Ca2+-ATP 酶、琥珀酸脱氢酶 (SDH) 和细胞色素 C 氧化酶 (CCO)。此外，MLT处理导致脯氨酸积累增加，这可能是鸟氨酸-δ-转氨酶（OAT）和Delta（1）-吡咯啉-5-羧酸合酶（P5CS）活性增加以及脯氨酸脱氢酶（PDH）活性抑制的结果。这些结果表明，MLT处理后荔枝果实耐冷性的增强可能与能量和脯氨酸代谢的调节有关。
Melatonin (MLT) is a vital signaling molecule that regulates multiple physiological processes in higher plants. In the current study, the role of MLT in regulating chilling tolerance and its possible mechanisms in litchi fruit during storage at ambient temperatures after its removal from refrigeration was investigated. The results show that the application of MLT (400 mu M, dipping for 20 min) to 'Baitangying' litchi fruit effectively delayed the development of chilling injury (CI) while inhibiting pericarp discoloration, as indicated by higher chromacity values (L*, a*, b*) and anthocyanin levels. MLT treatment suppressed the enhancements of the relative electrical conductivity (REC) and malondialdehyde (MDA) content, which might contribute to the maintenance of membrane integrity in litchi fruit. MLT treatment slowed the decline in cellular energy level, as evidenced by higher adenosine triphosphate (ATP) content and a higher energy charge (EC), which might be ascribed to the increased activities of enzymes associated with energy metabolism including H+-ATPase, Ca2+-ATPase, succinate dehydrogenase (SDH), and cytochrome C oxidase (CCO). In addition, MLT treatment resulted in enhanced proline accumulation, which was likely a consequence of the increased activities of ornithine-delta-aminotransferase (OAT) and Delta(1)-pyrroline-5-carboxylate synthase (P5CS) and the suppressed activity of proline dehydrogenase (PDH). These results suggest that the enhanced chilling tolerance of litchi fruit after MLT treatment might involve the regulation of energy and proline metabolism.