Metal-Chelating Agents from Ectomycorrhizal Fungi and Their Biotechnological Potential

Abstract

Ectomycorrhizal fungi can contribute to protecting their host plants when these develop in degraded soils, poor in mineral micronutrients and/or contaminated with metal ions. The mechanisms involved in the fungi's protective effect have not been completely clarified and the participation of metal-chelating agents of low molecular weight has been suggested. These agents include siderophores, highly iron-specific, and organic acids like oxalate and citrate, which can be released into the soils by the mycorrhized roots or the extraradical mycelium. The metal-chelating agents modify the bioavailability of metal ions in natural environments, contributing to the weathering of soils. Another important group of chelators are the thiol-peptides metallothioneins, phytochelatins, and reduced glutathione, which have been related to intracellular detoxification mechanisms and metal accumulation in some macromycetes. Effective chelator production is responsible for the biotechnological potential of ectomycorrhizal fungi in the development of new strategies for bioremediation or the revegetation of disturbed forest ecosystems.