Phosphate supply and arsenate toxicity in ectomycorrhizal fungi

Abstract

Three species of ectomycorrhizal fungi (Hebeloma crustuliniforme, Suillus variegatus and Cenococcum geophilum) were grown in axenic culture amended with range of AsO43- concentration under three different PO43- regimes. The fungi exhibited different growth responses to AsO43- that varied with PO4 3- concentration. Suillus variegatus showed the greatest sensitivity to AsO43-, with growth almost completely inhibited in the presence of AsO43- under the lower two PO4 3- treatments. Under the highest PO43- treatment however, growth was enhanced and S. variegatus was able to persist at AsO43- concentrations of up to 4 mM. Hebeloma crustuliniforme also showed high sensitivity to AsO43- especially at low PO43- concentration. The two higher PO43- treatments had an ameliorating effect on AsO 43- toxicity in H. crustuliniforme. This demonstrates the ability of PO43- to alleviate AsO43- toxicity. The response from S. variegatus and H. crustuliniforme, both basidiomycetes, was in contrast to the ascomycete C. geophilum. This fungus demonstrated tolerance to AsO43- when grown in culture solution and PO43- did not have an ameliorating effect on AsO43- toxicity in C. geophilum. Show more