Copper compartmentalization in spores as a survival strategy of arbuscular mycorrhizal fungi in Cu-polluted environments

Abstract

Arbuscular mycorrhizal (AM) fungi are present in Cu-polluted soils. By using in vivo cultures of Claroideoglomus claroideum in association with Imperata condensata and monoxenic cultures of Rhizophagus irregularis in association with carrot roots we show for the first time the presence of AM fungal spores of a green–blue colour in Cu-polluted environments. In both experiments, the number of green–blue spores increased with Cu concentration in the soil or in the culture medium. The green–blue colour was associated with an accumulation of Cu in the spore cytoplasm. These spores were metabolically inactive. These data suggest that a fungal strategy to survive in Cu-polluted environments is to compartmentalize the excess metal in some spores.