Allozymes of A WildAgaricus BisporusPopulation: New Alleles, New Genotypes

Abstract

Eighteen field-collected isolates ofAgaricus bisporus from coastal central California and two extra? limital field isolates were subjected to allozyme analysis via PAGE, and were genotypically scored at six polymorphic loci. This population sample carries previously unreported alleles at three of five loci for which a large culture collection (PSUMCC), composed primarily of cultivar lines, had previously been screened. Only one allele known from the PSUMCC collection was not found in the wild popu? lation. Novel combinations of previously known alleles were also found. With one exception, each field isolate was genetically unique within the field sample. The wild population of A. bisporus thus contains a large number of novel genotypes that are not represented in cultivar lines. These facts strongly suggest that A. bisporus is indigenous to North America. Our observations, particularly the discovery of several new alleles, also indicate that the wild population of this species represents a significant reservoir of genetic information presently unexploited by the commercial mushroom industry. In contrast, four of the field-collected isolates could be assigned to genotypic classes known from the PSUMCC collection or other cultivars. These findings support the widely-held belief that cultivars of A. bisporus do escape from commercial cultivation and can reproduce under natural conditions.