Relationship between fruiting body development and extracellular laccase production in the edible mushroom Flammulina velutipes

The biochemical mechanism underlying the development of fruiting bodies in Flammulina velutipes, an edible mushroom, was investigated using the YBLB colorimetric assay to distinguish between the normal strain (FVN-1) and the degenerate strain (FVD-1). In this assay, the color of the YBLB medium (blue-green) inoculated with FVN-1 exhibiting normal fruiting body development changed to yellow, while the color of the medium inoculated with FVD-1 changed to blue. In this study, we found that this color difference originated from extracellular laccase produced by FVN-1. Moreover, FVN-1 exhibited considerably higher extracellular laccase activity than FVD-1, under conditions facilitating fruiting body formation. Overall, these findings suggest that extracellular laccase is involved in the fruiting body development process in F. velutipes.