Role and influence of mycorrhizal fungi on radiocesium accumulation by plants

Abstract

This review summarizes current knowledge on the contribution of mycorrhizal fungi to radiocesium immobilization and plant accumulation. These root symbionts develop extended hyphae in soils and readily contribute to the soil-to-plant transfer of some nutrients. Available data show that ecto-mycorrhizal (ECM) fungi can accumulate high concentration of radiocesium in their extraradical phase while radiocesium uptake and accumulation by arbuscular mycorrhizal (AM) fungi is limited. Yet, both ECM and AM fungi can transport radiocesium to their host plants, but this transport is low. In addition, mycorrhizal fungi could thus either store radiocesium in their intraradical phase or limit its root-to-shoot translocation. The review discusses the impact of soil characteristics, and fungal and plant transporters on radiocesium uptake and accumulation in plants, as well as the potential role of mycorrhizal fungi in phytoremediation strategies.

Effects of arbuscular mycorrhizal fungi on caesium accumulation and the ascorbate-glutathione cycle of Sorghum halepense

“…Declerck et al demonstrated that the extraradical hyphal network of AMF incorporate and translocate radiocaesium from a radiocaesium labelled root-free compartment to a root compartment, using a monoxenic multicompartment growing system 18 . De Boulois et al suggested that there was the possibility, although limited, of radiocaesium accumulation in the intraradical mycelium 19 . Chen et al also reported that AMF raised the biomass of Pteris vittata, significantly, when increased U concentrations in the root, and had a high transfer factor value, indicating that the intraradical hyphae may take advantage of microorganisms and rhizosphere microenvironment to transform radionuclides in soil effectively 20 .…”

Impact of arbuscular mycorrhizal fungi on uranium accumulation by plants

“…These authors investigated whether the extraradical mycelium of Glomus intraradices (MUCL 41833) could take up U and translocate it towards its host. The experimental system selected for this first study was an in vitro bi-compartmented culture system (Dupré de Boulois et al, 2008;Declerck et al, 2005). Briefly, this system allows the culture of root organs in association with an AM fungus under monoxenic culture conditions and permits transport studies where only the fungal partner has access to a compartment containing a radio-tracer (Rufyikiri et al, 2005).…”

“…Rufyikiri et al (2002) therefore suggested that polyphosphates could play a major role in the immobilization of U by G. intraradices. However, it should be pointed out that polyphosphates are not immobile, as they are involved in the translocation of P, and probably other elements from the extraradical hyphae to the intraradical structures of AM fungi (see Dupré de Boulois et al, 2008). Nonetheless, if we suppose that polyphosphates participate in the immobilization of U in the extraradical mycelium, it should be noticed that the pH of the cytoplasm, and of organelles of AM fungal mycelium is probably stable due to close metabolic control as it can be observed for any organisms or cellular compartment (Ayling et al, 1997;Kurkdjian and Guern, 1989).…”

Radiocaesium activity concentrations in macrofungi from Galicia (NW Spain): Influence of environmental and genetic factors

“…The behavior and transport of radionuclides in soil, plants and mushrooms have been the object of many investigations (Malinowska et al, 2006;Kaduka et al, 2006;Bazała et al, 2008;Bystrzejewska-Piotrowska and Bazała, 2008;Dupré de Boulois et al, 2008;Mietelski et al, 2010). The main factors controlling the 137 Cs levels in mushrooms are mycelium depth and ecophysiological behavior of fungi.…”

“…This is because the dynamic of radionuclides in soils depends not only on their physicchemical interactions with inorganic and organic soil constituents, but also on biological interaction associated, to a large extent, with the microbial activity of the soil-plant-system. Therefore, after the disaster of Chernobyl, harvest and consumption of EMC fruiting bodies were restricted, or even directly forbidden, in contaminated sites (Dupré de Boulois et al, 2008).…”