Effects of light on fruit-body formation in a basidiomycete, Coprinus macrorhizus

A basidiomycete, Coprinus macrorhizus produced only vegetative mycelia, when cultured under continuous darkness. Under continuous white light, visible tiny primordia formed on the 6th day after inoculation, followed by normal development to fruit-bodies. Spores disseminated on the 11th day. However, when cultures where transferred to continuous darkness after the formation of primordia, rudimentary pilei with slender stalks formed. Abundant hairy hyphae were produced along the entire surface of the slender stalks. Thus, light was required-for both the initiation and development of the fungal fruit-body. A fairy ring of primordia formed along the narrow region of mycelia formed just prior to the exposure to light, provided a colony was pre-grown for more than 4 days in the dark, then exposed to light for 24 hr or longer. Exposure to light for at least 48 hr during the period between 24th and 96th hr after primordium initiation was required for normal maturation of the fruit-body. This 48 hr light period needed for maturation of the fruit-body could be substituted by two, 2 hr light periods given at the beginning and the end of the 48 hr period. We have tentatively concluded that light is required at two definite stages for fruit-body development after formation of the primordium. Effective wavelengths for both the initiation and development of fruit-bodies were in the near ultraviolet and blue regions.