Project R-2075

Molecular mechanisms of zinc tolerance in Suillus luteus. (Research)

Zinc is an essential micronutrient for all organisms but can become toxic when present in elevated concentrations. The quantity of free zinc in the cell has to be controlled precisely to assure growth and reproduction in all circumstances, in spite of the potential toxic nature of this element. Eukaryotes evolved a zinc homeostasis network restricting the zinc influx, storing it in specific organelles and/or chelating it when present in elevated concentrations [1]. However, at prolonged exposure or in case of extremely elevated concentrations in the environment, these basic detoxification mechanisms are not longer sufficient for most organisms and tolerant ecotypes can evolve due to selective pressure. The ectomycorrhizal fungus, Suillus luteus, evolved ecotypes with an adaptive tolerance for zinc, cadmium and/or copper. These ecotypes can protect their host from toxicity and are of crucial importance for the preservation of vegetation on contaminated sites [2,3,4]. Own research pointed out that adaptive zinc tolerance in Suilloid fungi relies on active transport of zinc out of the cell [5,6]. Transcriptome analysis yielded a lot of TDFs (transcript derived fragments) of which a few could be linked to zinc detoxification but of which none could be linked directly to the transport of zinc or zinc complexes [7]. Therefore the players of the zinc homeostasis network, responsible for adaptive tolerance in Suilloid fungi, are still unknown. Objectives of the project The overall objective of the current project is to unravel the molecular biological mechanism responsible for adaptive zinc tolerance in Suilloid fungi. To realize this overall objective, three sub objectives are set: 1. Identify and characterize some components of the zinc homeostasis network of Suillus luteus. There will be focused on cation transporters with a function in zinc fluxes. 2. Gain an understanding of the regulation of the zinc homeostasis network. Upstream components will be identified and will shed light on the zinc sensing mechanism of the eukaryotic fungus cell. 3. Determine the interaction of other metals and the zinc homeostasis network.

01 January 2010 - 31 December 2013