Uranium (U) is a naturally occurring radionuclide and heavy metal present in both aquatic and terrestrial environments at relatively low concentrations. Due to anthropogenic activities such as metal mining milling, nuclear energy production and the phosphate industry, U concentrations have locally risen causing ecological problems (Vandenhove 2002).
Since U is a non-essential element, plants have to cope with exposure to this unwanted chemical element. The U toxicity and availability to plants has been intensively studied in recent years. However, to conduct a proper risk assessment, it is necessary to predict the uptake by the roots and the translocation to other parts of the plant. Since the U-uptake mechanisms are largely unknown, there is still a lack of information.
We hypothesize that (i) U is taken up through specific transport mechanisms in plants, (ii) Fe, Ca and/or P-ions alter U uptake and translocation in plants and (iii) U influences Fe, Ca and P uptake and homeostasis in plants which can lead to U-induced stress responses.
After conducting a literature research, the competition between U and Fe, Ca, or P uptake will be investigated through tracer studies (i.e. using radiolabelled Fe, Ca and P) or using mutants of Arabidopsis thaliana with altered Fe, Ca and P homeostasis. In a next step, the U microlocalisation will be determined using SEM coupled with energy dispersive spectroscopy. Finally, we will further increase the knowledge on the mechanistic understanding of U uptake by using holistic approaches (e.g. RNA sequencing).
This research will be done in collaboration with J. Bourguignon from CEA (France). This will involve an exchange of the PhD students for a few months to CEA in Grenoble (France).