High-frequency occurrence of virus-like particles with double-stranded RNA genome in Fusarium poae

Fifty-five geographically different strains of Fusarium poae were assayed for the presence of extrachromosomal nucleic acid elements. All strains were found to harbour double-stranded RNA (dsRNA) elements and encapsidated virus-like particles (VLP). There were great individual differences in dsRNA patterns of the various strains, but numbers and sizes characteristic for a given isolate remained unchanged after repeated subculturing of the fungi. Morphological alterations or signs of degeneration were not observed in dsRNA-containing isolates. This is the first report on the ubiquitous occurrence of dsRNAs in a hyphomycete fungus species.