Arsenate sensitivity in ericoid and ectomycorrhizal fungi
Isolates of the endomycorrhizal fungus Hymenoscyphus ericae and the ectomycorrhizal fungus Hebeloma crustuliniforme from soils uncontaminated with AsO{sub 4}{sup 3{minus}}, were compared with regard to their sensitivity to AsO{sub 4}{sup 3{minus}} in solution culture. When grown in liquid media amended with a range of AsO{sub 4}{sup 3{minus}} concentrations, H. ericae demonstrated reduced sensitivity to AsO{sub 4}{sup 3{minus}} compared to H. crustuliniforme. The concentrations causing 50% inhibition of growth (EC50) were 1.33 mol/m{sup 3} and 0.33 mol/m{sup 3}, respectively, for H. ericae and H. crustuliniforme. The compound AsO{sub 4}{sup 3{minus}} is a PO{sub 4}{sup 3{minus}} analogue for the plasmalemma PO{sub 4}{sup 3{minus}} transporter. The presence of PO{sub 4}{sup 3{minus}} in the media at high concentrations ameliorated the toxic effects of AsO{sub 4}{sup 3{minus}} in both the ericoid and ectomycorrhizal fungi. This could be due to both suppression of the PO{sub 4}{sup 3{minus}} transporter under high phosphorus status and competition of PO{sub 4}{sup 3{minus}} with AsO{sub 4}{sup 3{minus}} for the transport protein. The kinetics of AsO{sub 4}{sup 3{minus}} influx in H. ericae and H. crustuliniforme were also investigated. Hymenoscyphus ericae demonstrated a high K{sub m} value, 0.071 mol/m{sup 3}, consistent with values obtained for AsO{sub 4}{sup 3{minus}}-tolerant plants. The authors suggest that the high K{sub m} value may be a mechanism used by H. ericae to express reduced AsO{sub 4}{sup 3{minus}} sensitivity. The ecological significance of this reduced sensitivity is also discussed.
- Research Organization:
- Univ. of Western Sydney, Kingswood, New South Wales (AU)
- OSTI ID:
- 20012740
- Journal Information:
- Environmental Toxicology and Chemistry, Vol. 18, Issue 8; Other Information: PBD: Aug 1999; ISSN 0730-7268
- Country of Publication:
- United States
- Language:
- English
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