XVI International Botanical Congess

Investigations on detoxification mechanisms in mycorrhizal fungi, which could be useful in amelioration of metal toxicity to plants on heavily polluted sites, were carried out. Some fungi change the properties of hyphal wall or plasma membrane, produce extracellular metal complexing substances or intercellular metalothionein-like substances. The sequestration of potentially toxic elements within vacuoles might be also an important mechanism involved. In some ectomycorrhizas the decrease of heavy metal sequestration within the fungal mantle towards the inside of the root was shown. In orchids, from wastes rich in Zn, Cd, As and Pb, the heavy metals were mostly accumulated within mycorrhizal mycelium and the amounts of these elements transfered to the shoots were very low. In arbuscular mycorrhiza the inhibition of arbuscule development by mycelium containing high level of heavy metals was observed. Also plants developed mechanisms to detoxify the metals transfered by the fungus.