Biological Species in Pleurotus
RONALD H. PETERSEN, KAREN W. HUGHES, AND NADEZHDA PSURTSEVA
Mating System
Self-crosses performed with exemplar collections have revealed uniformly tetrapolar mating systems (but see P. abieticola for exception). Ratios of mating types is almost always skewed, with some mating types often not represented in the sample. Techniques for harvesting monokaryon isolates and pairing them may be found by Gordon and Petersen (1991).
Monokaryon isolates may be obtained from at least three sources: a) basidiospores, either dropped by pieces of pileus (with lamellae) on agar and then carefully excised to individual cultures (in this lab, termed "single-basidiospore isolates" or SBIs; see Gordon and Petersen, 1991); b) neohaploidization, in which dikaryon cultures are grown on a high-stress agar (in this lab, ox-gall agar), under which conditions they revert to monokaryon state (see Petersen, 1992); or c) protoplasting, in which dikaryon mycelium is exposed to enzymes which degrade the hyphal wall, with the release of small, membrane-bound protoplasmic contents, from which are harvested non-nuclear, monokaryon, and dikaryon elements. Monokaryons are later selected by lack of clamp connections.