Morphogenesis in Schizophyllum commune. I. Effects of White Light

Reproductive differentiation in the basidiomycete Schizophyllum commune Fr. is initiated by plasmogamy and reciprocal nuclear migration and is terminated by the production of basidiospores. The work reported here has analyzed several factors that affect 2 sequential steps in reproductive differentiation: A) the formation of aggregated masses of cells, and B) the subsequent differentiation of fruiting bodies. The 2 steps are both photosensitive: A) light accelerates the formation of aggregated masses of cells; B) a short exposure of light induces nonaggregated dikaryotic cells to form mature fruiting bodies in the dark. Cultures of dikaryotic mycelia showed little or no response to light during approximately the first 60 hr of growth. Subsequent to this time, they were photosensitive. Several properties of the photoinduction of fruiting bodies were established in studies utilizing white fluorescent light. (1) The morphogenetic response (fruiting) was approximately linear with the amount of light delivered at low intensities; higher intensities elicited no further response. (2) The photoresponse did not vary when replicate cultures were irradiated at temperatures of 2 degrees , 24 degrees , or 35 degrees . (3) The induction of fruiting bodies by light is disrupted by post-induction heat-exposures of 50 degrees for 1 hr or longer. (4) Photoinduced fruiting bodies formed in distinctive rings on the mycelia and thus suggested that cells of different ages differ in their ability to be photoinduced.