Cultural Studies and Genetics of Sexuality of Ganoderma Lucidum and G. Tsugae in Relation to the Taxonomy of the G. Lucidum Complex

ABSTRACT

Ganoderma lucidum and G. tsugae are two members of the G. lucidum complex that have had a controversial taxonomic relationship. The authenticity of the two widely distributed wood-rotting species was demonstrated by comparative studies. Specimens and isolates of both species were obtained from several locations in North America. Ganoderma lucidum is restricted to hardwoods. Its basidiospores were “smooth” walled, characterized by narrow, numerous inter-wall pillars, as observed by bright-field and scanning electron microscopy. Isolates of G. lucidum produced chlamydospores in culture and had an average growth rate of 7.8 mm/da at its optimum temperature range of 30–34 C. Ganoderma tsugae is restricted to conifers. Its basidiospores were “rough” walled and had broad interwall pillars. Isolates of G. tsugae did not produce chlamydospores in culture and had an average growth rate of 2.1 mm/da at the optimum temperature range of 20–25 C. Basidiospore sizes could not be used to distinguish the species. Mating systems were determined for both species as heterothallic and tetrapolar. Interspecific matings of homokaryons were completely incompatible. Cultures of G. resinaceum and G. valesiacum from Europe were similar in morphology and temperature relationships to North American cultures of G. lucidum and G. tsugae, respectively. Homokaryons of a European G. resinaceum isolate that fruited in culture were completely interfertile with homokaryons from North American collections of G. lucidum. History of the G. lucidum complex is considered with reference to the pleomorphic characteristics used in earlier taxonomy.

Key words:

• Ganoderma
• incompatibility
• interfertility