Phosphate supply and arsenate toxicity in ectomycorrhizal fungi

Three species of ectomycorrhizal fungi ( Hebeloma crustuliniforme , Suillus variegatus and Cenococcum geophilum ) were grown in axenic culture amended with range of AsO 4 3– concentration under three different PO 4 3– regimes. The fungi exhibited different growth responses to AsO 4 3– that varied with PO 4 3– concentration. Suillus variegatus showed the greatest sensitivity to AsO 4 3– , with growth almost completely inhibited in the presence of AsO 4 3– under the lower two PO 4 3– treatments. Under the highest PO 4 3– treatment however, growth was enhanced and S. variegatus was able to persist at AsO 4 3– concentrations of up to 4 mM. Hebeloma crustuliniforme also showed high sensitivity to AsO 4 3– especially at low PO 4 3– concentration. The two higher PO 4 3– treatments had an ameliorating effect on AsO 4 3– toxicity in H. crustuliniforme . This demonstrates the ability of PO 4 3– to alleviate AsO 4 3– toxicity. The response from S. variegatus and H. crustuliniforme , both basidiomycetes, was in contrast to the ascomycete C. geophilum . This fungus demonstrated tolerance to AsO 4 3– when grown in culture solution and PO 4 3– did not have an ameliorating effect on AsO 4 3– toxicity in C. geophilum. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)