Abstract
Isolates of the endomycorrhizal fungus Hymenoscyphus ericae and the ectomycorrhizal fungus Hebeloma crustuliniforme from soils uncontaminated with AsO43-, were compared with regard to their sensitivity to AsO43- in solution culture. When grown in liquid media amended with a range of AsO43- concentrations, H. ericae demonstrated reduced sensitivity Co AsO43- compared to H. crustuliniforme. The concentrations causing 50% inhibition of growth (EC50) were 1.33 mol/m(3) and 0.33 mol/m(3), respectively, for H. ericae and H. crustuliniforme. The compound AsO43- is a PO43- analogue for the plasmalemma PO43- transporter. The presence of PO43- in the media at high concentrations ameliorated the toxic effects of AsO43- in both the ericoid and ectomycorrhizal fungi. This could be due to: both suppression of the PO43- transporter under high phosporus status and competition of PO43- with AsO43- for the transport protein. The kinetics of AsO43- influx in H. ericae and H. crustuliniforme were also investigated. Hymenoscyphus ericae demonstrated a high K-m value, 0.071 mol/m(3), consistent with values obtained for AsO43--tolerant plants. We suggest that the high K-m value may be a mechanism used by H. ericae to express reduced AsO43- sensitivity. The ecological significance of this reduced sensitivity is also discussed.
Original language | English |
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Pages (from-to) | 1848-1855 |
Number of pages | 8 |
Journal | Environmental Toxicology and Chemistry |
Volume | 18 |
Issue number | 8 |
DOIs | |
Publication status | Published - Aug 1999 |
Keywords
- arsenate
- phosphate
- hymenoscyphus ericae
- hebeloma crustuliniforme
- sensitivity
- holcus-lanatus L
- phosphate-uptake system
- cespitosa L beauv
- pisolithus-tinctorius
- mycorrhizal infection
- metal resistance
- in-vitro
- tolerance
- growth
- transport