Transformation of the mushroom species Hypsizigus marmoreus, Flammulina velutipes, and Grifola frondosa by an Agrobacterium-mediated method using a universal transformation plasmid

Agrobacterium tumefaciens-mediated transformation (AMT) was successfully applied to mycelia of the 3 economically important mushrooms Hypsizigus marmoreus, Flammulina velutipes, and Grifola frondosa. We used the hygromycin B resistance gene (hph) under the control of the Cryptococcus neoformans actin promoter. Eighty-six resistant strains of H. marmoreus, 4 of F. velutipes, and 2 of G. frondosa were obtained. All transformants were highly resistant to hygromycin B, suggesting that the C. neoformans actin promoter has a potential universal promoter activity in basidiomycetes. Southern analysis revealed random but single integration of the hph gene.