Melatonin confers heavy metal-induced tolerance by alleviating oxidative stress and reducing the heavy metal accumulation in Exophiala pisciphila, a dark septate endophyte (DSE).
Melatonin confers heavy metal-induced tolerance by alleviating oxidative stress and reducing the heavy metal accumulation in Exophiala pisciphila, a dark septate endophyte (DSE).
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褪黑素通过减轻氧化应激和减少暗隔内生菌（DSE）的重金属积累，赋予重金属诱导的耐受性。
DOI：
10.1186/s12866-021-02098-1
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发表时间：
2021-02-05
期刊：
影响因子：
4.2
通讯作者：
Zhao Z
中科院分区：
文献类型：
--
作者：
Yu Y;Teng Z;Mou Z;Lv Y;Li T;Chen S;Zhao D;Zhao Z
褪黑素(MT)是几乎所有生物体中普遍存在的一种自由基清除剂。尽管有几份关于它在动物、植物和一些微生物中的抗氧化剂作用的报道，但对丝状真菌的广泛研究是有限的。基于褪黑素作为一种抗氧化剂的作用，我们通过研究褪黑素在减轻氧化胁迫和减少重金属积累方面的潜在机制，研究了褪黑素在重金属诱导的胁迫耐受中的作用。与对照相比，镉、锌和铅胁迫下，鱼腥藻体内的丙二醛(MDA)和氧自由基(OFR)显著降低。200.0 μM外源褪黑素处理能显著提高锌、铅胁迫下的超氧化物歧化酶活性。200.0 μM褪黑素处理也显著降低了Cd、Zn和Pd的浓度。镉、铜、锌可促进褪黑激素的合成，并上调褪黑激素生物合成酶基因--鱼腥藻色氨酸脱羧酶和5-羟色胺N-乙酰转移酶基因的转录水平。EPTDC1和N-乙酰-5-羟色胺O-甲基转移酶(EpASMT1)在大肠杆菌和拟南芥中的过表达提高了其对重金属胁迫的耐受性。EPTDC1和EpASMT1基因的过表达降低了刺参植株中Cd的积累，尤其是根中Cd的积累。褪黑素通过减轻氧化应激，激活抗氧化酶超氧化物歧化酶，减少重金属在鱼腥藻中的积累，赋予重金属诱导的应激耐受性。鱼腥藻的褪黑素生物合成酶基因也在限制海藻体内过量积累重金属方面发挥了关键作用。这些发现可以扩展到理解褪黑素在其他与经济上重要的植物相关的DSE中的作用，并有助于开发可持续农业实践中的新策略，即植物可以在受重金属污染的土壤中生长。网上版载有补充材料，可在10.1186/s12866-021-02098-1查阅。
Melatonin (MT), ubiquitous in almost all organisms, functions as a free radical scavenger. Despite several reports on its role as an antioxidant in animals, plants, and some microorganisms, extensive studies in filamentous fungi are limited. Based upon the role of melatonin as an antioxidant, we investigated its role in heavy metal-induced stress tolerance in Exophiala pisciphila, a dark septate endophyte (DSE), by studying the underlying mechanisms in alleviating oxidative stress and reducing heavy metal accumulation. A significant decrease in malondialdehyde (MDA) and oxygen free radical (OFR) in E. pisciphila was recorded under Cd, Zn, and Pb stresses as compared to the control. Pretreatment of E. pisciphila with 200.0 μM exogenous melatonin significantly increased the activity of superoxide dismutase (SOD) under Zn and Pb stresses. Pretreatment with 200.0 μM melatonin also lowered Cd, Zn, and Pb concentrations significantly. Melatonin production was enhanced by Cd, Cu, and Zn after 2 d, and melatonin biosynthetic enzyme genes, E. pisciphila tryptophan decarboxylase (EpTDC1) and serotonin N-acetyltransferase (EpSNAT1), were transcriptionally upregulated. The overexpression of EpTDC1 and N-acetylserotonin O-methyltransferase (EpASMT1) in Escherichia coli and Arabidopsis thaliana enhanced its heavy metal-induced stress tolerance. The overexpression of EpTDC1 and EpASMT1 reduced the Cd accumulation in the whole A. thaliana plants, especially in the roots. Melatonin conferred heavy metal-induced stress tolerance by alleviating oxidative stress, activating antioxidant enzyme SOD, and reducing heavy metal accumulation in E. pisciphila. Melatonin biosynthetic enzyme genes of E. pisciphila also played key roles in limiting excessive heavy metal accumulation in A. thaliana. These findings can be extended to understand the role of melatonin in other DSEs associated with economically important plants and help develop new strategies in sustainable agriculture practice where plants can grow in soils contaminated with heavy metals. The online version contains supplementary material available at 10.1186/s12866-021-02098-1.
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