Identification of laccase-like genes in ectomycorrhizal basidiomycetes and transcriptional regulation by nitrogen in Piloderma byssinum

Ectomycorrhizal (ECM) fungi were screened for laccase-like genes by polymerase chain reaction (PCR) using primers for white rot fungal laccase genes, and expression of the genes was examined by reverse transcriptase polymerase chain reaction (RT-PCR) for Piloderma byssinum in axenic culture under different nutrient conditions. Laccase-like genes were present in Rhizopogon roseolus along with several Russulales and Atheliaceae taxa, and showed strong nucleotide sequence similarity to laccase genes in white rot fungi. Multiple laccase-like genes were only identified in Piloderma spp. Laccase-like genes were expressed in Piloderma spp., with transcript levels some six times higher under high nitrogen conditions in P. byssinum than when nitrogen availability was lower. The potential roles of laccases in nutrient mobilization and/or differentiation of multihyphal ECM fungal structures are discussed.