SEXUAL INCOMPATIBILITY IN SUILLUS-LUTEUS AND S-GRANULATUS

Intrastock pairings of homokaryons from one North American and four Swedish spore collections of Suillus luteus showed in all cases a bipolar sexual incompatibility. The heterokaryons produced were easily recognized as such by a morphology, cytology and growth rate which differed from that of the homokaryons. All five stocks were inter-compatible, which shows the conspecificity of the Swedish and the American strains. Analogous tests were made with homokaryons of S. granulatus comprising four American and three Swedish strains. Only in one of the Swedish strains did the pairings give rise to a heterokaryotic mycelium morphologically different from the homokaryons. Cytological evidence and the presence of clamps in most of these heterokaryons confirmed the conclusion that S. granulatus is also bipolar. No mating reactions were seen in the pairings with American homokaryons of S. granulatus. Generally, the American isolates gave the impression of species taxonomically different from the Swedish ones. © 1990, British Mycological Society. All rights reserved.