Study of arbuscular mycorrhizal fungi under hydrocarbon-polluted conditions and diversity associated to plants communities naturally recolonizing oil ponds in the Amazonian areas

ELI - Soutenance publique de thèse – Mme Mónica Cristina GARCES RUIZ
Promoteurs : Professeur Stéphane Declerck (UCL) et Docteur Sylvie Cranenbrouck (UCL)

Oil exploitation and its mishandling impact fauna and flora. Several oil-polluted sites have been identified in the Amazon region of Ecuador. Their recovery is necessary and the biological strategies (i.e. phytoremediation assisted by microbes) an attractive option increasingly considered. Arbuscular mycorrhizal fungi (AMF) are obligate root symbionts which effects on plant nutrition and resistance/tolerance to abiotic stresses is well known. However, the community composition of AMF in oil-polluted soils and the impact of pollutants on the physiological roles of these fungi are poorly known. In this context, our thesis aimed: 1) to study the AMF community composition in highly oil-polluted soils naturally recolonized by native plants. Results revealed the presence of several, mostly unknown, AMF species suggesting their adaptation to hydrocarbon pollutants. 2) to determine the role of the AMF R. irregularis MUCL 41833 on the uptake and transport of Pi to maize in presence of diesel. No beneficial effect of AMF was noticed. Diesel impacted Pi uptake, plant growth and AMF root colonization. However, it is not excluded that AMF isolated from the oil-polluted soils could improve plant resistance/tolerance to diesel. 3) to investigate the impact of diesel on the hyphae healing mechanism, a major mechanism of AMF to recover following injury. Two AMF species with contrasting life history strategies (i.e. R. irregularis and Gigaspora sp.) were compared and showed differences in their ability to heal under increasing concentrations of diesel.
Phytoremediation assisted by well-adapted AMF may represent an innovative restoration strategy for hydrocarbon-polluted environments.