Identification of novel double-stranded RNA mycoviruses of Fusarium virguliforme and evidence of their effects on virulence.

Virulence and double-stranded RNA (dsRNA) profiles of 44 isolates of Fusarium virguliforme were compared. When grouped according to dsRNA profiles, isolates with large dsRNAs were significantly (P≤0.05) less virulent than isolates without dsRNAs. High-throughput sequence analysis of total RNA prepared from cultures with large dsRNAs identified two novel RNA viruses with genome sequences of approximately 9.3 kbp, which were named Fusarium virguliforme dsRNA mycovirus 1 and Fusarium virguliforme dsRNA mycovirus 2. The new viruses were most closely related to a group of unclassified viruses that included viruses of F. graminearum and Phlebiopsis gigantea and are related to members of the family Totiviridae.