Mechanism of arsenate resistance in the ericoid mycorrhizal fungus Hymenoscyphus ericae

J M Sharples, A A Meharg, S M Chambers, J W Cairney

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Abstract

Arsenate resistance is exhibited by the ericoid mycorrhizal fungus Hymenoscyphus ericae collected from As-contaminated mine soils. To investigate the mechanism of arsenate resistance, uptake kinetics for arsenate (H(2)AsO(4)(-)), arsenite (H(3)AsO(3)), and phosphate (H(2)PO(4)(-)) were determined in both arsenate-resistant and -non-resistant H. ericae. The uptake kinetics of H(2)AsO(4)(-), H(3)AsO(3), and H(2)PO(4)(-) in both resistant and non-resistant isolates were similar. The presence of 5.0 microM H(2)PO(4)(-) repressed uptake of H(2)AsO(4)(-) and exposure to 0.75 mM H(2)AsO(4)(-) repressed H(2)PO(4)(-) uptake in both H. ericae. Mine site H. ericae demonstrated an enhanced As efflux mechanism in comparison with non-resistant H. ericae and lost approximately 90% of preloaded cellular As (1-h uptake of 0.22 micromol g(-1) dry weight h(-1) H(2)AsO(4)(-)) over a 5-h period in comparison with non-resistant H. ericae, which lost 40% of their total absorbed H(2)AsO(4)(-). As lost from the fungal tissue was in the form of H(3)AsO(3). The results of the present study demonstrate an enhanced H(3)AsO(3) efflux system operating in mine site H. ericae as a mechanism for H(2)AsO(4)(-) resistance. The ecological significance of this mechanism of arsenate resistance is discussed.
Original languageEnglish
Pages (from-to)1327-34
Number of pages8
JournalPlant Physiology
Volume124
Issue number3
Publication statusPublished - 2000

ASJC Scopus subject areas

  • Plant Science

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    Sharples, J. M., Meharg, A. A., Chambers, S. M., & Cairney, J. W. (2000). Mechanism of arsenate resistance in the ericoid mycorrhizal fungus Hymenoscyphus ericae. Plant Physiology, 124(3), 1327-34.