1,8-dihydroxy naphthalene (DHN) - melanin confers tolerance to cadmium in isolates of melanised dark septate endophytesMarjana Regvar
, Jože Grdadolnik
, Iztok Arčon
, Katarina Vogel-Mikuš
, Matevž Likar
, Mateja Potisek
, 2021, izvirni znanstveni članek
Opis: 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.
Najdeno v: ključnih besedah
Povzetek najdenega: ...DSE, melanin, Cd tolerance, inhibitor tricyclazole, antioxidant enzymes, EXAFS...
Ključne besede: DSE, melanin, Cd tolerance, inhibitor tricyclazole, antioxidant enzymes, EXAFS
Objavljeno: 13.07.2021; Ogledov: 754; Prenosov: 0
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