Using total RNA sequencing, we detected a novel RNA virus infecting a Finnish isolate of the fungal conifer pathogen Diplodia sapinea, and its genome sequence was verified by Sanger sequencing. This virus, which we have named "Diplodia sapinea flexi-like virus 1" (DsFLV1), has a 7,494-nucleotide-long positive-sense single-stranded RNA genome, excluding the poly(A) tail. The largest open reading frame (ORF1) encodes a replication-associated polyprotein (RP) that contains conserved domains characteristic of members of the order Tymovirales, including viral methyltransferase (Mtr), viral helicase (Hel), and RNA-dependent RNA polymerase (RdRP) domains. Four smaller ORFs were also identified. ORF2 potentially encodes a capsid protein, while the other three ORFs, initiated by alternative start codons, encode putative proteins with unknown functions. Phylogenetic analysis placed DsFLV1 in a distinct clade within the family Deltaflexiviridae, close to Erysiphe necator-associated flexivirus 2. This is the first report of a positive-sense single-stranded RNA virus infecting D. sapinea.

Department of Forest Protection and Wildlife Management Faculty of Forestry and Wood Technology Mendel University in Brno Brno Czech Republic

Natural Resources Institute Natural Resources Forest Health and Biodiversity Helsinki Finland

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