Efficient Transformation of the Medicinal Mushroom Ganoderma lucidum

Ganoderma lucidum is a well-known and important medicinal mushroom, but its genetic modification has not been reported. We developed an efficient procedure for isolation and regeneration of protoplasts from G. lucidum. To construct a vector for high-level expression of heterologous genes in G. lucidum, the 1.4-kb regulatory region of the glyceraldehyde-3-phosphate dehydrogenase gene (GPD) was isolated from the genomic DNA of Lentinus edodes, and the GPD promoter was fused to the β-glucuronidase (GUS) and bialaphos resistance (bar) genes. Using the resulting construct, p301-bG1, an efficient transformation system based on electroporation was established for G. lucidum. GUS expression was observed among transformants conferring bialaphos resistance, indicating that the L. edodes GPD promoter can be used for expression of exogenous genes in G. lucidum. We also studied green fluorescent protein (GFP) as another reporter for transformation of G. lucidum. The L. edodes GPD promoter was fused respectively to the GFP and bar genes, and the resulting construct, p301-bg, was introduced into G. lucidum. Stable GFP expression in transformants was detectable by fluorescence microscopy, suggesting the suitability of GFP as a reporter system in transformation of this mushroom. This is the first report of an efficient transformation system for G. lucidum using different reporters, paving the way for genetic modification of this famous medicinal mushroom.