Evidence for a novel negative-stranded RNA mycovirus isolated from the plant pathogenic fungus Fusarium graminearum

Highlights: • A novel (−)ssRNA mycovirus FgNSRV-1 was isolated from Fusarium graminearum. • FgNSRV-1 genome is 9072 nt in length with five discontinuous but linear ORFs. • FgNSRV-1 is classified into the family Mymonaviridae of the order Mononegavirales. • The virions of FgNSRV-1 are filamentous, 35–50 nm in diameter, ~1200 nm in length. • FgNSRV-1 infected host fungus resulted in no discernable phenotypic change. Here we describe a novel (−)ssRNA mycovirus, Fusarium graminearum negative-stranded RNA virus 1 (FgNSRV-1), isolated from Fusarium graminearum strain HN1. The genome of FgNSRV-1 is 9072 nucleotides in length, with five discontinuous but linear ORFs (ORF I-V). Phylogenetic analysis based on entire L polymerase sequences indicated that FgNSRV-1 is related to the (−)ssRNA mycovirus Sclerotinia sclerotiorum negative-stranded RNA virus 1 (SsNSRV-1), and other mycoviruses. Our data suggest that FgNSRV-1 can be classified into the family Mymonaviridae, order Mononegavirales. Putative enveloped virion-like structures with filamentous morphology similar to SsNSRV-1 were observed in virion preparation samples. The L proteins of FgNSRV-1, and other fungal mononegaviruses, were found to be related to L protein-like sequences in some fungal genome, supporting the hypothesis that there is coevolution occurring between mycoviruses and fungi. Besides, clearing the virus from the infected host fungus resulted in no discernable phenotypic change.