Zinc ions differentially affect chitin synthase gene expression in an ericoid mycorrhizal fungus.

Two chitin synthase (Chs) genes (class II and class IV, respectively) were identified in the mycelium of strain PSIV, a sterile ascomycete capable of establishing ericoid mycorrhiza. Both genes were constitutively expressed during mycelial growth in liquid medium. However, when the fungus was challenged with toxic amounts of zinc ions, the accumulation of class II, but not class IV, Chs mRNAs was inhibited. To our knowledge, this is the first report on the differential expression of distinct Chs mRNAs following exposure to heavy metals.