THE MATING SYSTEM OF PHELLINUS-TREMULAE

Basidiocarps of Phellinus tremulae were collected from trembling aspen (Populus tremuloides) in Alberta, Saskatchewan, and Ontario. A mating study based on single spore isolates of 12 of these basidocarps was p erformed using carrot agar, malt agar, and malt-yeast agar media. Resu lts from carrot agar showed that the fungus is heterothallic and has a tetrapolar mating system. Mating studies on malt agar and malt-yeast agar were inconclusive. The mating factor genes were multiallelic. Com patible and incompatible matings could be recognized microscopically. Radial growth rate of heterokaryon colonies did not differ significant ly from that of homokaryon colonies. When genetically different hetero karyotic isolates were paired on agar media a zone of antagonism forme d where the two colonies met. No zone of antagonism occurred between g enetically identical heterokaryon colonies.