Melatonin confers heavy metal-induced tolerance by alleviating oxidative stress and reducing the heavy metal accumulation in Exophiala pisciphila, a dark septate endophyte (DSE)

BMC Microbiology

Suiyun Chen¹  Zongmin Mou¹  Dake Zhao¹  Yan Lv²  Zhaowei Teng²  Yang Yu³  Tao Li³  Zhiwei Zhao³ 

[1] Biocontrol Engineering Research Center of Plant Disease and Pest, Yunnan University, Kunming, China;Biocontrol Engineering Research Center of Crop Disease and Pest, Yunnan University, Kunming, China;School of Ecology and Environmental Science, Yunnan University, Kunming, China;Department of Orthopedics, The Sixth Affiliated Hospital of Kunming Medical University, Yuxi, Yunan, China;Department of Orthopedics, The First people’s Hospital of Yunnan Province, Kunming, China;State Key Laboratory for Conservation and Utilization of Bio-resources in Yunnan, Yunnan University, Kunming, China;

关键词: Dark septate endophytes;    Heavy metals accumulation;    Melatonin;    Biosynthesis genes;    Oxidative stress;   

DOI  :  10.1186/s12866-021-02098-1

来源: Springer

【 摘 要 】

BackgroundMelatonin (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.ResultsA 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.ConclusionsMelatonin 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.

【 授权许可】

CC BY