Vegetative Incompatibility Between Intraspecific Dikaryotic Pairings ofGanoderma LucidumandG. Tsugae

Intraspecific pairings of dikaryons of Ganoderma lucidum and G. tsugae were conducted on 2% malt extract agar (MEA) and on wood blocks of Quercus hypoleucoides and Abies concolor. Intraspecific pairings of dikaryons from different trees formed interaction zones regardless of geographical distribution. Self-crosses of dikaryons were compatible. Antagonistic reactions on MEA after 10 wk were sparsely colonized, clear zones between opposing cultures. Four types of zone lines developed on the wood blocks after 20 wk: (1) discolored zones of undecayed wood on oak blocks; (2) nondiscolored zones of undecayed wood on white fir blocks; (3) hyphal interaction zones in surface mycelium and within wood of both wood types; and (4) noninteraction zone lines in surface mycelium of both wood types. Evidently, characters of the host wood influenced formation of the interaction zones. Antagonistic hyphal interactions on MEA and wood blocks consisted of hyphae with swellings and abnormal branching where hyphal fusion occurred. Hyphal noninteraction lines appeared randomly on the surface of the wood blocks where densely packed, pigmented cuticular cells were formed. No self-pairings of dikaryons showed interaction zones and hyphae anastomosed freely. Homokaryons from different G. lucidum dikaryons were interfertile. Homogenicity between dikaryotic isolates of both species apparently allows plasmogamy to occur. Vegetative incompatibility delimits individuals of different genotypes in natural populations of G. lucidum and G. tsugae.