Characterization of Botrytis cinerea negative-stranded RNA virus 1, a new mycovirus related to plant viruses, and a reconstruction of host pattern evolution in negative-sense ssRNA viruses.

The molecular characterization of a novel negative single-stranded RNA virus infecting the plant pathogenic fungus Botrytis cinerea is reported here. Comparison of the sequence of Botrytis cinerea negative-stranded RNA virus 1 (BcNSRV-1) showed a strong identity with RNA dependent RNA polymerases (RdRps) of plant pathogenic emaraviruses and tospoviruses. We have also found all the molecular signatures present in the RdRp of the genus Emaravirus and in other genera of family Bunyaviridae: the conserved TPD triplet and RY dinucleotide, the three basic residues in premotif A and the conserved motifs A, B, C, D, and E. Our results showed that BcNSRV-1 is phylogenetically close to members of the genus Emaravirus and of the family Bunyaviridae, and an ancestral state reconstruction using the conserved RdRp motifs of type members of each family of (-)ssRNA viruses indicated that BcNSRV-1 could possibly derive from an invertebrate and vertebrate-infecting virus.