Indigenous and introduced populations ofAgaricus bisporus, the cultivated button mushroom, in eastern and western Canada: implications for population biology, resource management, and conservation of genetic diversity

Abstract

Agaricus bisporus is known from field collections in several parts of southern Canada and the border states of Washington and Idaho. In Ontario, the species is associated with urban horticultural sites, agricultural areas, and thoroughfares. In British Columbia, Washington, and Idaho, the species is less well documented but occurs in habitats similar to those in Ontario. All studied isolates from these two regions were genotypically similar to those collected in Europe and also to a representative sample of cultivar isolates believed to be of European origin. In contrast, a population from forests of Picea in the Rocky Mountains of Alberta had genotypes that are very different from European and cultivar groups, including the putatively introduced populations in other parts of Canada. To a lesser extent, the Albertan individuals also differed from three other isolated natural populations, two in California and one in Israel. Two of 35 isolates from Alberta had nuclear genotypes that were partially or entirely consistent with European ancestry, indicating that foreign (probably cultivar) germ plasm has become established in the native habitat. Thirty of 35 isolates from the Alberta field sample had one of six mitochondria1 DNA (mtDNA) haplotypes known only from Alberta; the remaining five had an mtDNA type known from cultivar strains. However, nuclear genotypic similarity to other Albertan or European-cultivar isolates was not significantly correlated with presence or absence of this latter mtDNA type. The genetic diversity represented by the previously unknown Albertan population, and to a lesser extent by the heirloom varietal lineages and their derivatives that have become established in Ontario, British Columbia, Washington, and Idaho, is an important resource for breeders of this valuable fungal crop species. Threats to resource populations of this species, and possible responses, are discussed.

Molecular phylogeny, biogeography and speciation of the mushroom species Pleurotus cystidiosus and allied taxa

“…This finding is in agreement with the pattern of population structure of another broadly distributed mushroom, Schizophyllum commune (James et al, 1999(James et al, , 2001). The vectors responsible for long distance dispersal in fungi are still poorly known, but recent human-mediated dispersal has been invoked (Coetzee et al, 2000;Kerrigan et al, 1995).…”

“…Although oceans are an effective barrier to gene exchange and long distance spore dispersal is not an effective means of gene flow between continents (Hughes et al, 1999;Kerrigan et al, 1995;Lickey et al, 2002;Petersen, 1995;Shen et al, 2002;Vilgalys, 1986), common incompatibility alleles have been detected in intercontinental populations of P. cystidiosus, i.e. in populations from the USA and Taiwan (Moore, 1985;Zervakis, 1998 produce basidiospores with a particular physiology of dormancy, which can withstand adverse environmental conditions over long distances and germinate only at relatively high temperatures and in the presence of suitable substrates (Lahouvaris et al, 1995).…”

“…This finding is in agreement with the pattern of population structure of another broadly distributed mushroom, Schizophyllum commune (James et al, 1999(James et al, , 2001). The vectors responsible for long distance dispersal in fungi are still poorly known, but recent human-mediated dispersal has been invoked (Coetzee et al, 2000;Kerrigan et al, 1995).Intercontinental distributions of mushroom fungi are governed in part by gene flow via long-distance spore dispersal, human-mediated transfer of substrates and/or commercial mushroom spawn, and vicariance events. Although oceans are an effective barrier to gene exchange and long distance spore dispersal is not an effective means of gene flow between continents (Hughes et al, 1999;Kerrigan et al, 1995;Lickey et al, 2002;Petersen, 1995;Shen et al, 2002;Vilgalys, 1986), common incompatibility alleles have been detected in intercontinental populations of P. cystidiosus, i.e.…”

“…The vectors responsible for long distance dispersal in fungi are still poorly known, but recent human-mediated dispersal has been invoked (Coetzee et al, 2000;Kerrigan et al, 1995).…”

Phylogeny of the GenusAgaricusInferred from Restriction Analysis of Enzymatically Amplified Ribosomal DNA

“…In fact, Malloch et al (1987) found the amount of variation between the ''two'' was no greater than the amount of variation among any two strains of cultivated A. bisporus. Additionally, A. bisporus has been collected in the wild (Kerrigan et al, 1995;Kerrigan and Ross, 1989). So, it seems the debate over the proper name may have been resolved in favor of A. brunnescens, though A. bisporus is likely to remain in use as it has been the accepted name in the literature for so long (Kerrigan, 1987).…”