KINETICS OF ASYMMETRIC MYCELIAL GROWTH AND CONTROL BY DIKARYOSIS AND LIGHT IN SCHIZOPHYLLUM-COMMUNE

An asymmetric form of mycelial growth is described for isolates of Sch izophyllum commune. This growth form is limited to dikaryons and is ch aracterized by a decreasing rate of hyphal extension followed by the d evelopment of a chaotic mycelial form when grown on semisolid media. T he component homokaryons of these dikaryons do not display this growth form but grow in a circularly symmetrical pattern. The chaotic growth of these dikaryons is induced by light. Dikaryons grown in total dark ness had rates of growth and mycelial pattern similar to that of homok aryons. Chaotic growth is also associated with an inability of dikaryo tic mycelia to fuse. Mycelia with a uniform growth habit will always f use, while chaotic mycelia fuse only with difficulty on fresh medium w hen inoculated less than 10 mm apart. The kinetics of dikaryotic growt h and the results of the fusion tests suggest the presence of an auto- inhibitor of growth regulated by light and dikaryosis.