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Cao GH, He S, Chen D, Li T, Zhao ZW. EpABC Genes in the Adaptive Responses of Exophiala pisciphila to Metal Stress: Functional Importance and Relation to Metal Tolerance. Appl Environ Microbiol 2019; 85:e01844-19. [PMID: 31540987 PMCID: PMC6856334 DOI: 10.1128/aem.01844-19] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2019] [Accepted: 09/14/2019] [Indexed: 11/20/2022] Open
Abstract
Exophiala pisciphila is one of the dominant dark septate endophytes (DSEs) colonizing metal-polluted slag heaps in southwest China. It shows numerous super-metal-tolerant characteristics, but the molecular mechanisms involved remain largely unknown. In the present study, the functional roles of a specific set of ATP-binding cassette (ABC) transporters in E. pisciphila were characterized. In total, 26 EpABC genes belonging to 6 subfamilies (ABCA to ABCG) were annotated in previous transcriptome sequencing libraries, and all were regulated by metal ions (Pb, Zn, and Cd), which was dependent on the metal species and/or concentrations tested. The results from the heterologous expression of 3 representative EpABC genes confirmed that the expression of EpABC2.1, EpABC3.1, or EpABC4.1 restored the growth of metal-sensitive mutant Saccharomyces cerevisiae strains and significantly improved the tolerance of Arabidopsis thaliana to Pb, Zn, and Cd. Interestingly, the expression of the 3 EpABC genes further altered metal (Pb, Zn, and Cd) uptake and accumulation and promoted growth by alleviating the inhibitory activity in yeast and thale cress caused by toxic ions. These functions along with their vacuolar location suggest that the 3 EpABC transporters may enhance the detoxification of vacuolar compartmentation via transport activities across their membranes. In conclusion, the 26 annotated EpABC transporters may play a major role in maintaining the homeostasis of various metal ions in different cellular compartments, conferring an extreme adaptative advantage to E. pisciphila in metal-polluted slag heaps.IMPORTANCE Many ABC transporters and their functions have been identified in animals and plants. However, little is known about ABC genes in filamentous fungi, especially DSEs, which tend to dominantly colonize the roots of plants growing in stressed environments. Our results deepen the understanding of the function of the ABC genes of a super-metal-tolerant DSE (E. pisciphila) in enhancing its heavy metal resistance and detoxification. Furthermore, the genetic resources of DSEs, e.g., numerous EpABC genes, especially from super-metal-tolerant strains in heavy metal-polluted environments, can be directly used for transgenic applications to improve tolerance and phytoextraction potential.
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Affiliation(s)
- Guan-Hua Cao
- State Key Laboratory of Conservation and Utilization for Bioresources in Yunnan, Yunnan University, Kunming, Yunnan, China
- School of Traditional Chinese Medicine, Yunnan University of Chinese Medicine, Kunming, Yunnan, China
| | - Sen He
- School of Traditional Chinese Medicine, Yunnan University of Chinese Medicine, Kunming, Yunnan, China
| | - Di Chen
- School of Traditional Chinese Medicine, Yunnan University of Chinese Medicine, Kunming, Yunnan, China
| | - Tao Li
- State Key Laboratory of Conservation and Utilization for Bioresources in Yunnan, Yunnan University, Kunming, Yunnan, China
| | - Zhi-Wei Zhao
- State Key Laboratory of Conservation and Utilization for Bioresources in Yunnan, Yunnan University, Kunming, Yunnan, China
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Abstract
Allergic bronchopulmonary mycosis (ABPM) is a hypersensitivity reaction to fungal antigens, which may particularly plague uncontrolled asthmatics. Non-aspergillus fungal organisms may be implicated and may elicit a more severe immunologic response. Exophiala pisciphila, a marine organism, has not been reported as a culprit yet. However, this report indicates it may be implicated in unrelenting symptoms in a severe asthmatic patient who had become dependent on corticosteroids. Proper identification and adequate therapy of this organism led to complete resolution of respiratory symptoms, with adequate subsequent control of the asthma. ABPM may complicate asthma and lead to a lack of its control. Proper awareness, testing and treatment of non-aspergillus pulmonary mycosis is essential to proper asthma care and beneficial for its control.
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Affiliation(s)
- Jad Kebbe
- Department of Medicine, Division of Pulmonary, Critical Care and Sleep Medicine, University at Buffalo, The State University of New York, Buffalo, NY, USA
| | - M Jeffery Mador
- Department of Medicine, Division of Pulmonary, Critical Care and Sleep Medicine, University at Buffalo, The State University of New York, Buffalo, NY, USA
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Wei YF, Li T, Li LF, Wang JL, Cao GH, Zhao ZW. Functional and transcript analysis of a novel metal transporter gene EpNramp from a dark septate endophyte ( Exophiala pisciphila). Ecotoxicol Environ Saf 2016; 124:363-368. [PMID: 26595509 DOI: 10.1016/j.ecoenv.2015.11.008] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/08/2015] [Revised: 11/04/2015] [Accepted: 11/05/2015] [Indexed: 05/13/2023]
Abstract
Various metal transporters mediate sub-cellular sequestration of diverse metal ions, contribute to cellular metal tolerance, and control metal partitioning, particularly under conditions of high rates of metal influx into organisms. In the current study, a ubiquitous and evolutionary conserved metal transporter gene, homology to natural resistance associated macrophage protein (Nramp), was cloned from a metal-tolerant isolate of dark septate endophyte (DSE, Exophiala pisciphila), and its functional and transcript characterization were analyzed. The full-length Nramp gene from E. pisciphila (named EpNramp) was 1716 bp and expected to encode a polypeptide of 571 amino acid residues. EpNramp fused to green fluorescent protein suggested that EpNramp was a plasma membrane metal transporter, which was consistent with the results of bioinformatics analysis with 11 transmembrane domains. Yeast functional complementation revealed that EpNramp could complement the growth defect of Fe-uptake yeast mutant (fet3fet4 double mutant) by mediating the transport of Fe(2+). Expression of EpNramp increased Cd(2+) sensitivity and Cd(2+) accumulation in yeast. In addition, qPCR data revealed that E. pisciphila significantly down-regulated EpNramp expression with elevated Cd(2+) exposure. Altogether, EpNramp is a bivalent cation transporter localized in cell membrane, which is necessary for efficient translocation of both Fe and Cd, and its activities partly attributed to the tolerance of DSE to toxic and excessive Cd(2+) supplements.
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Affiliation(s)
- Yun-Fang Wei
- Key Laboratory of Conservation and Utilization for Bioresources and Key Laboratory of Microbial Diversity in Southwest China, Ministry of Education, Yunnan University, Kunming, 650091 Yunnan, PR China; Kunming Police Dog Base of the Ministry of Public Security, Kunming, 650204 Yunnan, PR China.
| | - Tao Li
- Key Laboratory of Conservation and Utilization for Bioresources and Key Laboratory of Microbial Diversity in Southwest China, Ministry of Education, Yunnan University, Kunming, 650091 Yunnan, PR China.
| | - Ling-Fei Li
- College of Food Science and Technology, Yunnan Agricultural University, Kunming, 650201 Yunnan, PR China.
| | - Jun-Ling Wang
- Key Laboratory of Conservation and Utilization for Bioresources and Key Laboratory of Microbial Diversity in Southwest China, Ministry of Education, Yunnan University, Kunming, 650091 Yunnan, PR China.
| | - Guan-Hua Cao
- Key Laboratory of Conservation and Utilization for Bioresources and Key Laboratory of Microbial Diversity in Southwest China, Ministry of Education, Yunnan University, Kunming, 650091 Yunnan, PR China.
| | - Zhi-Wei Zhao
- Key Laboratory of Conservation and Utilization for Bioresources and Key Laboratory of Microbial Diversity in Southwest China, Ministry of Education, Yunnan University, Kunming, 650091 Yunnan, PR China.
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Zhan F, He Y, Li Y, Li T, Yang YY, Toor GS, Zhao Z. Subcellular distribution and chemical forms of cadmium in a dark septate endophyte (DSE), Exophiala pisciphila. Environ Sci Pollut Res Int 2015; 22:17897-17905. [PMID: 26165995 DOI: 10.1007/s11356-015-5012-7] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/01/2015] [Accepted: 07/01/2015] [Indexed: 06/04/2023]
Abstract
Our objective was to understand the cadmium (Cd) tolerance mechanisms by investigating the subcellular distribution, chemical forms of Cd and adsorptive groups in the mycelia of Exophiala pisciphila. We grew E. pisciphila in the liquid media with increasing Cd concentrations (0, 25, 50, 100, 200, and 400 mg L(-1)). Increased Cd in the media caused a proportional increase in the Cd uptake by E. pisciphila. Subcellular distribution indicated that 81 to 97% of Cd was associated with the cell walls. The largest amount and proportion (45-86%) of Cd was extracted with 2% acetic acid, and a concentration-dependent extraction was observed, both of which suggest that Cd-phosphate complexes were the major chemical form in E. pisciphila. A large distribution of phosphate and Cd on the mycelia surface was observed by scanning electron microscopy-energy dispersive spectrometer (SEM-EDS). The precipitates associated with the mycelia were observed to contain Cd by transmission electron microscopy-energy dispersive X-ray spectroscopy (TEM-EDX). Fourier transform infrared (FTIR) identified that hydroxyl, amine, carboxyl, and phosphate groups were responsible for binding Cd. We conclude that Cd associated with cell walls and integrated with phosphate might be responsible for the tolerance of E. pisciphila to Cd.
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Affiliation(s)
- Fangdong Zhan
- College of Resources and Environment, Yunnan Agricultural University, Kunming, 650201, People's Republic of China
- Laboratory for Conservation and Utilization of Bio-Resources, and Key Laboratory for Microbial Resources of the Ministry of Education, Yunnan University, Kunming, 650091, People's Republic of China
| | - Yongmei He
- College of Resources and Environment, Yunnan Agricultural University, Kunming, 650201, People's Republic of China
| | - Yuan Li
- College of Resources and Environment, Yunnan Agricultural University, Kunming, 650201, People's Republic of China
| | - Tao Li
- Laboratory for Conservation and Utilization of Bio-Resources, and Key Laboratory for Microbial Resources of the Ministry of Education, Yunnan University, Kunming, 650091, People's Republic of China
| | - Yun-Ya Yang
- Soil and Water Quality Laboratory, Gulf Coast Research and Education Center, University of Florida, Wimauma, FL, 33598, USA
| | - Gurpal S Toor
- Soil and Water Quality Laboratory, Gulf Coast Research and Education Center, University of Florida, Wimauma, FL, 33598, USA
| | - Zhiwei Zhao
- Laboratory for Conservation and Utilization of Bio-Resources, and Key Laboratory for Microbial Resources of the Ministry of Education, Yunnan University, Kunming, 650091, People's Republic of China.
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Chen SY, Dickson DW, Mitchell DJ. Viability of Heterodera glycines Exposed to Fungal Filtrates. J Nematol 2000; 32:190-197. [PMID: 19270965 PMCID: PMC2620443] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/27/2023] Open
Abstract
Filtrates from nematode-parasitic fungi have been reported to be toxic to plant-parasitic nematodes. Our objective was to determine the effects of fungal filtrates on second-stage juveniles and eggs of Heterodera glycines. Eleven fungal species that were isolated from cysts extracted from a soybean field in Florida were tested on J2, and five species were tested on eggs in vitro. Each fungal species was grown in Czapek-Dox broth and malt extract broth. No toxic activity was observed for fungi grown in Czapek-Dox broth. Filtrates from Paecilomyces lilacinus, Stagonospora heteroderae, Neocosmospora vasinfecta, and Fusarium solani grown in malt extract broth were toxic to J2, whereas filtrates from Exophiala pisciphila, Fusarium oxysporum, Gliocladium catenulatum, Pyrenochaeta terrestris, Verticillium chlamydosporium, and sterile fungi 1 and 2 were not toxic to J2. Filtrates of P. lilacinus, S. heteroderae, and N. vasinfecta grown in malt extract broth reduced egg viability, whereas F. oxysporum and P. terrestris filtrates had no effect on egg viability.
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