Characterization of Two Novel Fusariviruses Co-Infecting a Single Isolate of Phytopathogenic Fungus Botrytis Cinerea

Abstract A wide diversity of mycoviruses have been reported from Botrytis species, some with the potential to supress the pathogenic abilities of this fungus. Considering their importance, this study was devised to find potential hypovirulence associated mycoviruses from in Botrytis cinerea strains isolated from Pakistani strawberry fields. Here we report complete genome characterization of two novel fusariviruses co-infecting single isolate of phytopathogenic fungus Botrytis cinerea. Viral genomes were sequenced via deep sequencing using total RNA fractions from isolate Kst14. Identified viruses were tentatively named Botrytis cinerea fusarivirus 8 (BcFV8) and Botrytis cinerea fusarivirus 9 (BcFV9). Both viruses had a single segmented (ssRNA) genome having a size of 6,424 and 8,370 nucleotides encoding two discontinuous open reading frames (ORFs). ORF1 of both viruses encodes for a poly-protein having a conserved domain of RNA dependent RNA polymerase (RdRP) and a helicase domain (Hel) which function in RNA replication, while ORF2 encodes a hypothetical protein with an unknown function, respectively. Phylogenetic analysis indicated that BcFV8 made clade with the genus alphafusariviruses and BcFV9 made fall in the genus betafusarivirus in the family Fusariviridae. To our knowledge, this is the first report of two fusariviruses identified in B. cinerea isolates from Pakistan. Both viruses successfully transfected to a compatible strain of Botrytis cinerea (Mst11). A comparison of virus free and infected isogenic line showed that the presence of these viruses was causing hypovirulence in infected strains. Virus infected strains also had a small lesion size while testing the pathogenicity via apple assay.