Zinc is an essential micromutrient for life. As a structural component of the zinc finger motifs found in many transcription factors and as a catalytic co-factor for RNA polymerase, zinc is required for gene transcription. Excess zinc, however, can be detrimental to cells. Industrial activities have led to large-scale contamination of the environment with toxic heavy metals. The further spread of these heavy metals remains a permanent and current problem. Phytostabilization and, in the future, phytoremediation offer a solution to this problem. In this project we want to find the genes that are responsible for the zinc tolerance of an ectomycorrhizal fungus Suillus luteus, found in a zinc-contaminated area in Lommel-Maatheide. Understanding the molecular mechanism used by this fungus to cope with excess Zn, can help us in the phytostabilization of contaminated areas. It is already clear that metal tolerant ectomycorrhizal fungi can help host plants to survive in this situation. We want to find this gene by using a cDNA-library of S. luteus, express this library in yeast (Saccharomyces cerevisiae) and screen for surviving clones. After checking the selected cDNAs in yeast, we want to transform a non-tolerant isolate of S. luteus with the tolerance-cDNA to check if the cDNA is really responsible for the zinc-tolerance. Eventually, we will perform some localization studies using a Green Fluorescent Protein (GFP) construct.