Mineral Transformations by Mycorrhizal Fungi

This review addresses the significance and the mechanisms of mineral weathering by mycorrhizal fungi, and the role of this process in plant nutrition and protection from metal toxicity. The fact that mycorrhizal mycelia may actively release nutrients from mineral particles through weathering is raising an increasing interest and the uptake of mineral-derived nutrients by the host plants has been reported. Both chemical dissolution (protonation, chelation) and physical mechanisms (high hyphal pressures) are involved in the weathering process. Mineral solubilization can result in the release of the associated toxic metals. Organic acid exudation and metal complexation may represent a host plant protection mechanism. Keywords: metal toxicitymineral weatheringmycorrhizal fungi We thank Andrea Genre for assistance with confocal microscopy and Ivana Fenoglio for the SEM analyses. E.M. and S.P. acknowledge financial support by the CEBIOVEM (D.M. 193/2003) program, Regione Piemonte (CIPE 2004) and Turin University grant (60%).