Survival strategies of arbuscular mycorrhizal fungi in Cu-polluted environments

This review provides an overview of the mechanisms evolved by arbuscular mycorrhizal (AM) fungi to survive in Cu-contaminated environments. These mechanisms include avoidance strategies to restrict entry of toxic levels of Cu into their cytoplasm, intracellular complexation of the metal in the cytosol and compartmentalization strategies. Through the activity of specific metal transporters, the excess of Cu is translocated to subcellular compartments, mainly vacuoles, where it would cause less damage. At the level of the fungal colony, AM fungi have also evolved compartmentalization strategies based on the accumulation of Cu into specific fungal structures, such as extraradical spores and intraradical vesicles. In addition to the avoidance and compartmentalization strategies, AM fungi have also mechanisms to combat the Cu-generated oxidative stress or to repair the damage induced.