Trehalose turnover during abiotic stress in arbuscular mycorrhizal fungi

Authors

  • Aurora Ocón,

    1. Physiological Ecology of Plants Department, Botanical Institute, University of Tübingen, Auf der Morgenstelle 1, D-72076 Tübingen, Germany;
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  • Rüdiger Hampp,

    1. Physiological Ecology of Plants Department, Botanical Institute, University of Tübingen, Auf der Morgenstelle 1, D-72076 Tübingen, Germany;
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  • Natalia Requena

    1. Physiological Ecology of Plants Department, Botanical Institute, University of Tübingen, Auf der Morgenstelle 1, D-72076 Tübingen, Germany;
    2. Present address: University of Karlsruhe, Institute for Applied Biosciences, Fungal–Plant Interactions Group, Hertzstrasse 16, D-76187 Karlsruhe, Germany
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Author for correspondence: Natalia Requena Tel: +49 721 608 4626 Fax: +49 721 608 4509 Email: natalia.requena@bio.uka.de

Summary

  • • Trehalose is a common reserve carbohydrate in fungi, whose role has been recently extended to other cellular functions, such as stress tolerance, glycolysis control, sporulation and infectivity of some pathogenic strains.
  • • To gain some insight into the role of trehalose during abiotic stress in arbuscular mycorrhizal (AM) fungi, we assessed trehalose content as well as transcriptional regulation and enzyme activity of neutral trehalase and trehalose-6-phosphate phosphatase in Glomus intraradices in response to heat shock, chemical or osmotic stress.
  • • Prolonged or intensive exposure to heat or chemical stress, but not osmotic stress, caused an increase of trehalose in the cell. We found this associated with transient up-regulation of the trehalose-6-P phosphatase (GiTPS2) transcript that coincided with moderate increases in enzyme activity. By contrast, there were no changes in neutral trehalase (GiNTH1) RNA accumulation in response to stress treatments, while they promoted, in most cases, an increase in activity. After stress had ceased, trehalose returned to basal concentrations, pointing to a role of neutral trehalase activity in heat shock recovery. A yeast complementation assay confirmed the role of neutral trehalase in thermotolerance.
  • • Taken together, these results indicate that trehalose could play a role in AM fungi during the recovery from certain stresses such as heat shock and chemical treatment.

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