Biological Cadmium Detoxification in Rice Using the Fungus Trametes Pubescens: A Promising and Feasible Approach

Abstract

Background: Cadmium is a widely dispersed metal element that may be released to the environment with accelerated anthropogenic activities. Rice with high cadmium content is a serious threat to food safety and human health. Results: A heavy metal-resistant white rot fungus Trametes pubescens MB 89 with remarkable ability to prevent rice from cadmium toxification has been investigated in this study. We have assessed the biosorption of this ectomycorrhizal fungus with high concentrations of Cd2+. Results indicate that the maximum removal rate of Cd2+ from aqueous solution (10 mg/L) by T. pubescens MB 89 was 53.13%. A biofilm was formed on the cell surface of mycelium with Cd (II) been reduced to Cd (0) in the form of nanoscale particles in aqueous solution. It was found that the functional groups of –OH, –NH, C-H, C=O, C-O, S=O on the surface of T. pubescens MB 89 participated in the Cd2+ detoxification process. The effect of rice plant colonization with T. pubescens MB 89 was investigated with the pot experiments showing that it could significantly promoted rice seedlings growth and reduced cadmium accumulation on rice tissues. Moreover, the fungal colonization could decrease the cadmium transport to the rice roots, ameliorate cadmium toxicity and ensure the normal absorption and transportation of nutrients by the roots. Conclusion: This study showed a promising potential for T. pubescens MB 89 to prevent cadmium toxification for the rice grains in paddy fields. To further investigate the mechanism of T. pubescens to protect and promote rice growth, our next research focus will be on the beneficial interactions of ectomycorrhizal fungi and the rice root system with the aid of the root-fungal interactome analysis.