MYCOREMED radiocaesium

Radiocaesium (Cs) pollution of agricultural, semi-natural and natural areas is a worldwide problem that has arisen from human activities. Because of the chemical similarity between Cs and potassium (K) plant uptake mechanisms cannot differentiate between these elements easily.

Rhizosphere processes involving soil micro-organisms are known to influence Cs uptake by roots. Among these micro-organisms, the arbuscular mycorrhizal (AM) fungi are expected to play a key role.

In terrestrial ecosystems, AM fungi are intimately associated with the roots of most plant species. These symbionts supply plants with essential mineral elements, in particular phosphorus, and water, in exchange for photosynthetic products from the plant.

The effect of AM fungi on Cs accumulation by plants is not yet clear. The objective of this PhD project is to elucidate the mechanisms involved in uptake of Cs by Medicago truncatula plants and its translocation from roots to shoot. The project will focus on the expression of K/Cs transporters in non-mycorrhizal and mycorrhizal plants in the presence and absence of Cs using Affymetrix Medicago GeneChip microarray technology. These experiments will allow the effect of AM fungi on Cs transport processes in plants to be determined, and the radioecological significance of AM fungi on Cs accumulation by plants to be assessed. This will inform the development of safer crop plants, which take up less Cs, and/or phytoremediation strategies oriented towards phytoextraction or phytostabilisation of contaminated soils.

Figure 1

Figure 1: Growth inhibition of Medicago truncatula by caesium. Caesium reduces plant height and root length and, at high concentrations, causes death of plants.