Characterization of sterile endophytic fungi from the mycorrhizae of subalpine plants

Abstract

Isolates of 117 dematiaceous and 10 hyaline, septate, sterile fungi were obtained from the roots of 26 plants belonging to Poaceae, Caryophyllaceae, Rosaceae, Ericaceae, Primulaceae, and Asteraceae from a subalpine dwarf shrub heath in the Alberta Rocky Mountains. The isolates were sorted into 33 culture groups based on colonial morphology. Strains representative of the different culture groups were compared with fungi of known identity (Cenococcum geophilum, Hymenoscyphus ericae, Phialocephala dimorphospora, Phialocephala fortinii, Phialophora finlandia) using restriction fragment analysis of an amplified portion of ribosomal DNA. Cluster analysis and ordination based on restriction fragment polymorphisms indicated that two-thirds of the isolates were closely related to or conspecific with Phialocephala fortinii, which therefore appears to represent the dominant root endophyte of the subalpine site. In culture, many of the Phialocephala fortinii isolates had sclerotia composed of compact masses of darkly pigmented and irregularly lobed, thick-walled hyphae. Five of the isolates clustered independently of the known isolates and are probably each representative of species other than the known strains. Key words: subalpine mycorrhizae, Phialocephala fortinii, restriction fragment length polymorphism, ribosomal DNA.