There are four dsRNAs segments present in the entomopathogenic fungus Metarhizium brunneum strain RCEF0766. The genomic segments dsRNA1 and dsRNA3 are of a novel virus, "Metarhizium brunneum bipartite mycovirus 1" (MbBV1), while dsRNA2 and dsRNA4 are the components of the Metarhizium brunneum partitivirus 2 (MbPV2), a member in genus Gammapartitivirus of the family Partitiviridae based on molecular analysis and RT-PCR. This suggests that the strain RCEF0766 was co-infected by two different mycoviruses. The complete genome sequence of MbBV1 was elucidated by high-throughput sequencing and RLM-RACE. MbBV1 consists of two dsRNAs (1987 and 1642 bp) encode open-reading frames (ORFs). The ORF1 in dsRNA 1 encode is a putative RNA-dependent RNA polymerase (RdRp) with the molecular weight of 68.08 kDa, while ORF2 in dsRNA 2 encodes a hypothetical protein with the molecular weight of 33.07 kDa. The deduced proteins of ORF1 and ORF2 have the highest identity to those of Erysiphe necator-associated bipartite virus 1 (76.88% and 65.30%). Based on the amino acid sequence of RdRp, MbBV1 is phylogenetically clustered together with the unassigned mycoviruses and represents a distinct lineage. Our study proposes that MbBV1 is a novel mycovirus with bisegmented dsRNA genomes and should be considered a new member of the unassigned group.
Keywords: Bipartite mycovirus 1; Metarhizium brunneum; Mycoviruses; Partitiviridae.
© 2022. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.