| Title: | 1,8-dihydroxy naphthalene (DHN) - melanin confers tolerance to cadmium in isolates of melanised dark septate endophytes |
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| Authors: | ID Potisek, Mateja (Author)
ID Likar, Matevž (Author)
ID Vogel-Mikuš, Katarina (Author)
ID Arčon, Iztok (Author)
ID Grdadolnik, Jože (Author)
ID Regvar, Marjana (Author) |
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| Files: |
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| Language: | English |
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| Work type: | Unknown |
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| Typology: | 1.01 - Original Scientific Article |
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| Organization: | UNG - University of Nova Gorica
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| Abstract: | The contribution of 1,8-dihydroxy naphthalene (DHN) melanin to cadmium (Cd) tolerance in two dark septate
endophytes (DSE) of the genus Cadophora with different melanin content was investigated in vitro. The DSE
isolate Cad#148 with higher melanin content showed higher tolerance to Cd than the less melanised Cad#149.
Melanin synthesis was significantly reduced by Cd in both isolates with uninhibited melanin synthesis, in a dosedependent
manner. Inhibition of melanin synthesis by tricyclazole reduced the relative growth of Cad#148
exposed to Cd and did not affect Cad#149. Cd accumulation was not altered by tricyclazole in the two isolates,
but it increased catalase and reduced glutathione reductase activity in more melanised Cad#148, indicating
higher stress levels. In contrast, in Cad#149 the enzyme activity was less affected by tricyclazole, indicating a
more pronounced role of melanin-independent Cd tolerance mechanisms. Cd ligand environment in fungal
mycelia was analysed by extended EXAFS (X-ray absorption fine structure). It revealed that Cd was mainly bound
to O- and S-ligands, including hydroxyl, carboxyl, phosphate and thiol groups. A similar proportion of S- and Oligands
(~35% and ~65%) were found in both isolates with uninhibited melanin synthesis. Among O-ligands
two types with Cd-O-C- and Cd-O-P- coordination were identified. Tricyclazole altered Cd-O- ligand environment
in both fungal isolates by reducing the proportion of Cd-O-C- and increasing the proportion of Cd-O-P coordination.
DHN-melanin, among other tolerance mechanisms, significantly contributes to Cd tolerance in more
melanised DSE fungi by immobilising Cd to hydroxyl groups and maintaining the integrity of the fungal cell wall. |
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| Keywords: | DSE, melanin, Cd tolerance, inhibitor tricyclazole, antioxidant enzymes, EXAFS |
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| Year of publishing: | 2021 |
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| Number of pages: | str. 1-9 |
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| Numbering: | Vol. 222, 222 |
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| PID: | 20.500.12556/RUNG-6646 |
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| COBISS.SI-ID: | 70067203 |
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| UDC: | 577 |
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| ISSN on article: | 0147-6513 |
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| DOI: | 10.1016/j.ecoenv.2021.112493 |
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| NUK URN: | URN:SI:UNG:REP:9QTOEXOO |
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| Publication date in RUNG: | 13.07.2021 |
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| Views: | 2051 |
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| Downloads: | 0 |
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