Artomyces pyxidatus (Auriscalpiaceae, Fungi) in the Great Smoky Mountains National Park: Individuals and Populations

Artomyces pyxidatus is a North-temperate saprophytic coral fungus found in Europe, Asia, and North America. Collections from the Great Smoky Mountains National Park were used in this study to define the size of an individual and elucidate gene flow between three locations within the park (Greenbrier, Sugarlands, Cataloochee). Molecular techniques were used to determine the relationships between populations and among individuals. Two inter-simple sequence repeat (ISSR) primers amplified segments of DNA scattered throughout the genome and together produced 26 variable bands. ISSR analysis appeared to be a reliable technique for defining individuals, but should be used in conjunction with other techniques that are able to eliminate ambiguity and ensure accuracy. The nuclear ribosomal ITS 1-5.8S-ITS 2 (ITS) repeat provided a more defined genetic region and was studied using restriction fragment length polymorphisms (RFLP). An insertional element located within a Group I intron contained by the ribosomal 18S subunit was found in most eastern North American A. pyxidatus collections and was amplified and used to supplement the other molecular analyses by verifying the identity of individuals (Lickey 2002).

Analyses based on genetic characterization of multiple fruitbodies from single logs indicated that several A. pyxidatus individuals could occupy a single substrate and that the mycelia could reach a measured size of 1.9 meters. Data also showed that the three GSMNP populations were not in Hardy-Weinberg equilibrium and were, therefore, not undergoing random gene exchange. A deficiency of heterozygotes suggested that the cause was inbreeding. The Greenbrier population appears to be the most genetically diverse based on Neighbor Joining and Principle Coordinates analyses. Both techniques indicated that the three populations were interrelated and had genetic characters that produced little phenetic clustering based on collection location. Unique ISSR alleles, however, were found in all three populations, suggesting some level of isolation.