Chronic toxicity of U on hairy roots of carrot (Daucus carota L.).

Most terrestrial flowering plants are associated with arbuscular mycorrhizal fungi which may improve the growth of plants and decrease the U uptake at high levels of U in soils. However, the respective tolerance of each partner of the symbiosis (the host roots and the hyphae) to U accumulation and toxicity is unknown. In a first step, we estimated the toxicity of U to non-inoculated roots of carrot under root-organ culture conditions. The results showed that the root growth and the final biomass was decreased of at least 50% for a concentration in nutrient gel of 10 ppm of U. Further experiments are carried out in similar conditions with inoculated roots to compare the U toxicity on roots and hyphae.