Sterile dematiaceous fungi are commonly isolated from plant roots.
They are often assigned to Mycelium radicis atrovirens, a name
originally proposed for black, sterile, fast-growing, pseudomycorrhizal
fungi. Dematiaceous fungi isolated from roots may be
mutualists, commensalists, or pathogens and, in the absence of sporulation,
identification is not possible. Forty-six isolates of
dematiaceous fungi from the roots of different hosts and locations were
characterized using restriction site mapping of polymerase
chain reaction amplified nuclear ribosomal DNA internal transcribed spacers.
The
restriction site maps were compared 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
Phialocephala fortinii-like. Phialocephala fortinii
has been reported as both pathogenic and non-pathogenic in a number of
hosts. There
was variation within the P. fortinii-like group suggesting
intraspecific variation or a species complex.