MOLECULAR CHARACTERIZATION OF DEMATIACEOUS ROOT ENDOPHYTES

Sterile dematiaceous fungi are commonly isolated from plant roots. The y are often assigned to Mycelium radicis atrovirens, a name originally proposed for black, sterile, fast-growing, pseudomycorrhizal fungi. D ematiaceous fungi isolated from roots may be mutualists, commensalists , or pathogens and, in the absence of sporulation, identification is n ot possible. Forty-six isolates of dematiaceous fungi from the roots o f different hosts and locations were characterized using restriction s ite mapping of polymerase chain reaction amplified nuclear ribosomal D NA internal transcribed spacers. The restriction site maps were compar ed to identified dematiaceous mycorrhizal and pseudomycorrhizal fungi. Computer generated trees (UPGMA and parsimony analysis) characterized two unknown isolates as Phialophora finlandia, an ectendomycorrhizal fungus. The majority of the isolates were characterized as Phialocepha la fortinii-like. Phialocephala fortinii has been reported as both pat hogenic and non-pathogenic in a number of hosts. There was variation w ithin the P. fortinii-like group suggesting intraspecific variation or a species complex.