Identification of heavy metal regulated genes from the root associated ascomycete Cadophora finlandica using a genomic microarray.

The ascomycete Cadophora finlandica, which can form mycorrhizas with ectomycorrhizal and ericoid hosts, is commonly found in heavy metal polluted soils. To understand the selective advantage of this organism at contaminated sites heavy metal regulated genes from C. finlandica were investigated. For gene identification a strategy based on a genomic microarray was chosen, which allows a rapid, genome-wide screening in genetically poorly characterized organisms. In a preliminary screen eleven plasmids covering eight distinct genomic regions and encoding a total of ten Cd-regulated genes were identified. Northern analyses with RNA from C. finlandica grown in the presence of either Cd, Pb or Zn revealed different transcription patterns in response to the heavy metals present in the growth medium. The Cd-regulated genes are predicted to encode several extracellular proteins with unknown functions, transporters, a centaurin-type regulator of intracellular membrane trafficking, a GNAT-family acetyltransferase and a B-type cyclin.