Dopamine acts as a strong water-soluble antioxidant that mediates many physiological processes in plants. In the present study, we utilized two cultivars to investigate the effect of dopamine in mitigating chilling stress in watermelon ( Citrullus lanatus ) seedlings. Under chilling stress, exogenous application of dopamine (100 μM) increased seedling health index by 23.32% (cv. Xi Nong NO. 8) and 35.19% (cv. Jing Xin NO. 1) compared to chilling-stressed seedlings alone. As the stress was prolonged, chilling treatment caused a significant reduction in net rates of photosynthesis and chlorophyll contents. Dopamine supplementation significantly mitigated these adverse effects caused by chilling stress. After 8 days of chilling stress, supplementation of dopamine to chilling treatment seedlings further increases in levels of proline in cv. Xi Nong NO. 8 and cv. Jing Xin NO. 1 by 45.24% and 58.28%, respectively. Our results indicated that application of dopamine further enhanced antioxidant enzymes, which contributed to alleviate oxidative stress-induced chilling treatment. In addition, application of dopamine significantly improved polyamine levels by stimulating enzymes involved in the polyamine metabolism. From these outcomes, it is clear that supplementation of dopamine mitigates the harmful effects of chilling stress in watermelon seedlings through modulation of osmolytes, antioxidant enzymes, and polyamine metabolism.

中文翻译：

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多巴胺通过调节脯氨酸含量、抗氧化酶活性和多胺代谢减轻西瓜幼苗的寒冷应激

多巴胺作为一种强的水溶性抗氧化剂，介导植物的许多生理过程。在本研究中，我们利用两个栽培品种来研究多巴胺在减轻西瓜 ( Citrullus lanatus ) 幼苗低温胁迫中的作用。在低温胁迫下，与单独的低温胁迫幼苗相比，外源施用多巴胺 (100 μM) 使幼苗健康指数提高了 23.32% (cv. Xi Nong NO. 8) 和 35.19% (cv. Jing Xin NO. 1)。随着胁迫时间的延长，低温处理导致光合作用和叶绿素含量的净速率显着降低。多巴胺补充剂显着减轻了由冷应激引起的这些不利影响。在 8 天的低温胁迫后，向低温处理幼苗补充多巴胺进一步增加了 cv. 中脯氨酸的水平。西农号 8 和简历。景新号 1 分别为 45.24% 和 58.28%。我们的结果表明，多巴胺的应用进一步增强了抗氧化酶，这有助于减轻氧化应激引起的寒冷处理。此外，多巴胺的应用通过刺激参与多胺代谢的酶显着提高了多胺水平。从这些结果来看，很明显，补充多巴胺可以通过调节渗透物、抗氧化酶和多胺代谢来减轻西瓜幼苗低温胁迫的有害影响。多巴胺的应用通过刺激参与多胺代谢的酶显着提高了多胺水平。从这些结果来看，很明显，补充多巴胺可以通过调节渗透物、抗氧化酶和多胺代谢来减轻西瓜幼苗低温胁迫的有害影响。多巴胺的应用通过刺激参与多胺代谢的酶显着提高了多胺水平。从这些结果来看，很明显，补充多巴胺可以通过调节渗透物、抗氧化酶和多胺代谢来减轻西瓜幼苗低温胁迫的有害影响。