show Abstracthide AbstractThe basidiomycete Agaricus bisporus is cultivated at a global scale for the production of white button mushrooms. These fruiting bodies have high nutritional value and contain bioactive compounds. Development of A. bisporus mushrooms is a complex process. At this moment, the molecular mechanisms underlying mushroom formation are poorly understood. For instance, transcription factors involved in control of white button development have not been identified. Such regulatory proteins have been identified in the model organism Schizophyllum commune. Expression analysis in other mushroom-forming basidiomycetes suggests that mushroom development in the Basidiomycota follows a core regulatory program with species specific variations that explain differences in morphology and sensitivity to environmental signals. In this study, the A. bisporus homologues of abovementioned regulatory proteins were investigated in the commercial strain A15 in order to validate the existence of this core regulatory program.