Arbuscular mycorrhizal fungi facilitate the uptake of radiocesium by Eleutherococcus sciadophylloides (araliaceae) – a pot-scale and field survey

Abstract

ABSTRACT Radiocesium (137Cs) contamination caused by the Fukushima Daiichi Nuclear Power Plant accident has posed a serious problem, especially for forest ecosystems. Phytoremediation is an effective decontamination method with less disturbance to the ecosystems than tree felling and soil removal. Eleutherococcus sciadophylloides is one of the 137Cs-accumulating tree species in Japan. However, the accumulation mechanism is not well understood. Herein, we aimed to clarify the contribution of the colonization of arbuscular mycorrhizal fungi (AMF) to 137Cs uptake by E. sciadophylloides based on both field and greenhouse experiments. In the greenhouse experiment, we used a growth pot system with a mesh partition, which enable to confirm separately the contribution of AMF hyphae from tree roots. In addition, because potassium (K) in the rhizosphere is related to 137Cs uptake, we also aimed to clarify the role of AMF in 137Cs uptake by E. sciadophylloides in the presence of K. Semi-quantitative analysis of the field survey revealed a significant and positive relationship between AMF colonization and radioactivity in the fine roots of E. sciadophylloides. The pot experiments with K treatment indicated that AMF contributes to 137Cs uptake by E. sciadophylloides through its hyphae, and that the addition of K into the rhizosphere was effective in increasing the 137Cs uptake synergistically by AMF colonization. These results could prove helpful to future applications of AMF and K for enhanced phytoremediation of 137Cs by E. sciadophylloides.