Roles of root fungal endophytes in the tolerance of Fallopia to Metal Trace Elements

• Main Author: Barberis, Louise
• Other Authors: Laboratoire d'Ecologie des Hydrosystèmes Naturels et Anthropisés (LEHNA), Université Claude Bernard Lyon 1 (UCBL), Université de Lyon-Université de Lyon-École Nationale des Travaux Publics de l'État (ENTPE)-Centre National de la Recherche Scientifique (CNRS), Université de Lyon, Florence Piola, Serge Michalet, Philippe Binet
• Format: Doctoral or Postdoctoral Thesis
• Language: French
• Published: HAL CCSD 2020
• Subjects: Endophyte; Fallopia; Trace metal; Fungi; Root; Mutualism; Élément trace métallique; Champignon; Racine; Mutualisme; [SDV.BV]Life Sciences [q-bio]/Vegetal Biology; Sakhalin
• Online Access: https://theses.hal.science/tel-03456670; https://theses.hal.science/tel-03456670/document; https://theses.hal.science/tel-03456670/file/TH2020BARBERISLOUISE.pdf

Since the industrial revolution and the resulting contaminant emissions, soils have been subjected to increasingly high concentrations of trace metal elements (MTEs). These, which are non-biodegradable and toxic at low doses for most organisms, disrupt ecosystems and pose major environmental and health problems. However, many organisms, especially plants, have been able to adapt to the presence of MTEs in their environment: this is the case of Asian knotweeds, which are spreading in Europe, including in environments contaminated with MTEs. Like the majority of plants, knotweeds are associated with microorganisms, some of which, notably fungi present in their roots, could be involved in the tolerance of this plant to MTEs. The general objective of this thesis is to test this hypothesis, by studying the fungal species associated with the roots of Asian knotweeds and their roles in the tolerance of this taxon to metallic pollution of soils, under controlled conditions. For this purpose, rhizomes of knotweed (Japanese knotweed, Sakhalin knotweed and their hybrid Bohemian knotweed) were grown in greenhouses, in the presence or absence of MTEs (Cd, Cr, Zn and their mixture). Fungal colonization of the roots was quantified by microscopy and strains were isolated to characterize them. Secondary metabolites present in the roots and in some isolated strains were identified and quantified. A bibliographical study (Axis 1) inventorying the fungal endophytes present in plant roots and their effects on the tolerance of their host to MTEs has highlighted the ubiquity (host and environmental diversity) of root fungal endophytes, their taxonomic diversity and their growth stimulating properties of their plant host. In environments contaminated with MTEs, these endophytes inoculated to plants are also beneficial to their growth, but with various effects on the uptake and transfer of MTEs in plant tissues.Two experiments under controlled conditions were carried out to study the effect of metals on Knotweed on the one hand, and to ...