Gábor M. Kovács, Asfaw Zegeye, Corinne Leyval, Charlotte Berthelot, Dalia A. Gaber, Michel Chalot, Philipp Franken, Damien Blaudez, Laboratoire Interdisciplinaire des Environnements Continentaux (LIEC), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire Terre et Environnement de Lorraine (OTELo), Institut national des sciences de l'Univers (INSU - CNRS)-Université de Lorraine (UL)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Lorraine (UL)-Centre National de la Recherche Scientifique (CNRS)-Institut Ecologie et Environnement (INEE), Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS), Centre Technique Interprofessionnel des Fruits et Légumes (CTIFL), Assiut University, Leibniz Institute of Vegetable and Ornamental Crops (IGZ), Laboratoire Chrono-environnement - CNRS - UBFC (UMR 6249) (LCE), Centre National de la Recherche Scientifique (CNRS)-Université de Franche-Comté (UFC), Université Bourgogne Franche-Comté [COMUE] (UBFC)-Université Bourgogne Franche-Comté [COMUE] (UBFC), Faculté des Sciences et Technologies [Université de Lorraine] (FST ), Université de Lorraine (UL), Fachhochschule Erfurt [Erfurt], Plant Protection Institute [Budapest] (ATK NOVI), Centre for Agricultural Research [Budapest] (ATK), Hungarian Academy of Sciences (MTA)-Hungarian Academy of Sciences (MTA), Department of Plant Anatomy, Institute of Biology [Budapest], Faculty of Sciences [Budapest], Eötvös Loránd University (ELTE)-Eötvös Loránd University (ELTE)-Faculty of Sciences [Budapest], Eötvös Loránd University (ELTE)-Eötvös Loránd University (ELTE), This work was supported by the LORVER project funded by the Région Grand-Est and the EuropeanRegional Development Fund (ERDF), by the Groupement d’Intérêt Scientifique sur les Friches Industrielles (GISFI),by the French Environment and Energy Management Agency [PROLIPHYT ADEME-1172C0053] and by theAgence Nationale de la Recherche (ANR) under the Blanc International ANR-10-INTB-1703-01-BIOFILTREE project.The support by the ELTE Institutional Excellence Program supported by the National Research, Development andInnovation Oce (NKFIH-1157-8/2019-DT) is also acknowledged (GMK), ANR-10-INTB-1703,BIOFILTREE,Filtration biologique pour la réduction des éléments traces dans la biomasse des arbres(2010), Laboratoire de Chimie Physique et Microbiologie pour l'Environnement (LCPME), Centre National de la Recherche Scientifique (CNRS)-Université de Lorraine (UL), Observatoire Terre et Environnement de Lorraine (OTELo), Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS), Institut Ecologie et Environnement (INEE), Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire Terre et Environnement de Lorraine (OTELo), Institut national des sciences de l'Univers (INSU - CNRS)-Université de Lorraine (UL)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Lorraine (UL)-Centre National de la Recherche Scientifique (CNRS), Laboratoire Chrono-environnement - CNRS - UFC (UMR 6249) (LCE), Eötvös Loránd University (ELTE), and Hungarian Academy of Sciences (MTA)
Dark septate endophytes (DSEs) are often trace element (TE)-tolerant fungi and are abundant in TE-polluted environments. The production of melanin, a black polymer found in cell walls, was hypothesized by several authors to play a role in the TE tolerance of DSEs. To test this hypothesis, we established a series of experiments using albino strains and melanin inhibitors and examined the responses to Cd and Zn. Six DSEs belonging to genera Cadophora sp., Leptodontidium sp. and Phialophora mustea, were evaluated. The strains mainly produced 1,8-dihydroxynaphthalene (DHN) melanin whereas 3,4-dihydroxyphenylalanin melanin was also synthetized. Cd and Zn decreased melanin synthesis in most of the strains. A reduction in melanin concentration in hyphae through the use of tricyclazole, an inhibitor of DHN-melanin synthesis, did not reduce the tolerance of the strains to Cd and Zn. Similarly, albino mutants of Leptodontidium sp. were not more sensitive to Cd and Zn than the WT strain. Moreover, tricyclazole-treated colonies accumulated less Cd but more Zn compared to untreated colonies. The Cd and Zn contents of Leptodontidium albino strains were variable and similar to that of the WT. The results suggest that melanin production is not an important functional trait that contributes to Cd and Zn tolerance, but might contribute to Cd accumulation.