Showing papers on "Mycovirus published in 1990"

Significance of dsRNA Genetic Elements in Plant Pathogenic Fungi

Abstract: Phenotypic variability involving morphology, synthesis of secondary metabo­ lites, or virulence is not uncommon in filamentous fungi. Efforts to explain this phenomenon have stimulated interest in extrachromal genetic elements such as mycoviruses, plasmids, or transposons as modulators of fungal gene expression. DNA plasmids are not prevalent in filamentous fungi, and the incidence of transposable elements has only recently been reported (62). In contrast, mycoviruses and related double-stranded (ds) RNA genetic elements are found associated with fungi at a very high frequency. Consequently, the . contribution of these genetic elements to phenotypic variability has come under increased scrutiny. The first fungal viruses were isolated from mushrooms in 1962 (57), followed six years later by the discovery of viruses in Penicilliumfuniculosum

Evidence for viral and naked double-stranded RNAs in the basidiomycete Agrocybe aegerita

Abstract: Double-stranded (ds) RNAs were purified from the vegetative mycelium of the commercial basidiomycete Agrocybe aegerita, by gel-filtration chromatography, and their dsRNA nature was demonstrated. They were shown to be distributed in two different RNase-resistant complexes which were separated by sucrose density gradient ultracentrifugation: the first complex is the encapsidated genome (6200 bp) of an isometric mycovirus; the second consists of three naked dsRNA molecules (1900-1800-1700 bp respectively) associated with large vesicles or mitochondria. This is the first report of the presence of naked dsRNA, unencapsidated, viral genome fragments which have co-evolved with their host, or else represent new replicating genetic elements (dsRNA “plasmids”) of unknown function, in a non pathogenic higher fungus.