Effect of nonpathogenic Fusarium strains on the uptake rate of radionuclides by tomato

Radionuclides released into the environment enter the food chain through plants and fish among others, and pose a potential risk to human health. Eliminating radionuclides from the soil environment or reducing their uptake by food crops would decrease the dose for humans. The possibility of phytoremediation was suggested to reduce the amount of radionuclides in the soil. The transfer rate of radionuclides from the soil to the plant varies depending on soil characteristics and plant species. Rhizosphere microbes are also known to often affect the uptake of radionuclides from the soil by the plants. However, effects of microorganisms on the uptake rate of radionuclides by plants remain to be elucidated. Aiming at phytoremediation of soils polluted with radionuclides or at increasing the uptake ability of plants, we have analyzed the effect of microbes on the uptake ability of plants using the multitracer technique. Tomato is one of the plants capable of absorbing and accumulating radionuclides. We found that a tomato pathogenic strain of Fusarium (F. oxysporum, F . spio rycopersici) can enhance the uptake of Sr and Cs by the plant through infection. In this paper, we report on the effects of nonpathogenic strains of F . oxysporum, F . spio rycopersici (N.P.F.) on the uptake rate of radionuclides using the multitracer technique.