Recent studies have shown that melatonin is an important molecule in plant physiology. It seems that the most important is that melatonin efficacy eliminates oxidative stress (direct and indirect antioxidant) and moreover induce plant stress reaction and switch on different defence strategies (preventively and interventively actions). In this report, the impact of exogenous melatonin on carbohydrate metabolism in Nicotiana tabacum L. line Bright Yellow 2 (BY‐2) suspension cells during sugar starvation was examined. We analysed starch concentration, α‐amylase and PEPCK activity as well as proteolytic activity in culture media. It has been shown that BY‐2 cell treatment with 200 nM of melatonin improved viability of sugar‐starved cells. It was correlated with higher starch content and phosphoenolpyruvate carboxykinase (PEPCK) activity. The obtained results revealed that exogenous melatonin under specific conditions (stress) can play regulatory role in sugar metabolism, and it may modulate carbohydrate concentration in etiolated BY‐2 cells. Moreover, our results confirmed the hypothesis that if the starch is synthesised even in sugar‐starved cells, it is highly probable that melatonin shifts the BY‐2 cell metabolism on gluconeogenesis pathway and allows for synthesis of carbohydrates from nonsugar precursors, that is amino acids. These points to another defence strategy that was induced by exogenous melatonin applied in plants to overcome adverse environmental conditions.

中文翻译：

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褪黑素在植物细胞糖饥饿期间重定向碳水化合物的代谢

最近的研究表明褪黑激素是植物生理学中的重要分子。似乎最重要的是褪黑激素功效消除了氧化应激（直接和间接的抗氧化剂），并且诱发了植物的应激反应并启动了不同的防御策略（预防和干预作用）。在此报告中，外源褪黑素对烟草中碳水化合物代谢的影响检查了糖饥饿期间的L. line Bright Yellow 2（BY-2）悬浮细胞。我们分析了培养基中的淀粉浓度，α-淀粉酶和PEPCK活性以及蛋白水解活性。研究表明，用200 nM褪黑素对BY-2细胞进行处理可提高糖饥饿细胞的生存能力。这与较高的淀粉含量和磷酸烯醇丙酮酸羧激酶（PEPCK）活性有关。获得的结果表明，在特定条件下（应激）外源性褪黑激素可以在糖代谢中发挥调节作用，并且可以调节黄化BY-2细胞中的碳水化合物浓度。此外，我们的结果证实了以下假设：如果即使在糖缺乏的细胞中也能合成淀粉，褪黑激素很可能会改变糖异生途径上的BY-2细胞代谢，并允许从非糖前体（即氨基酸）合成碳水化合物。这些都指出了另一种防御策略，该策略是通过将外源褪黑素应用于植物来克服不利的环境条件而诱导的。