| Management of cultivated and semi-natural ecosystems which have been exposed to diffuse radionuclide (RN) pollution (e.g. radiocaesium) as well as remediation of former industrial sites contaminated with both metallic RN's and heavy metals are of major concern in several European countries. For example, uranium mining and milling, phosphate processing or coal mining resulted in high accumulation of RN's and/or heavy metals in soil surface layers of surrounding environment. Adapted strategies must be developed to optimize the socio-economical value of such sites and to avoid radiation exposure due to uncontrolled RN dispersion or leaching, which can burden food chain and/or water reservoir.
Different studies on RN biogeochemical cycle showed that RN fluxes depend on several factors, among which the type of soil and vegetation are of major importance. In particular, plant and soil interact in two key micro-ecosystems: the litter and the rhizosphere. The role of micro-organisms in this interaction is very important because they can directly act on several processes affecting RN fate: solubilization, complexation, sequestration, immobilization, transformation, precipitation. Of these organisms, the mycorrhizal fungi represents a key active compartment. These world-wide distributed symbionts are present in undisturbed ecosystems as well as in man-made agricultural and forestry systems and in heavy metals and RN contaminated areas. Their unique location at the interface between soil and root makes them key actors in the soil-to-plant continuum. These root symbionts could influence RN acquisition by plant roots and hence RN bio-cycling. Their role in this process is, however, practically unknown. With this in view, the general objective of the project aims at filling this gap in deciphering and understanding the role of mycorrhizal fungi in the mobilization and transfer of RN's to the plant. |