Molecular characterization of two dsRNAs that could correspond to the genome of a new mycovirus that infects the entomopathogenic fungus Beauveria bassiana.

Abstract

The entomopathogenic fungus Beauveria bassiana is used worldwide for biological control of insects. Seven dsRNA segments were detected in a single B. bassiana strain, RCEF1446. High-throughput sequencing indicated the presence of three mycoviruses in RCEF1446. Two were identified as the known mycoviruses Beauveria bassiana victorivirus 1 and Beauveria bassiana polymycovirus 1, and the novel mycovirus was designated as "Beauveria bassiana bipartite mycovirus 1" (BbBV1). The complete sequence of the BbBV1 is described here. The mycovirus contains two dsRNA segments. The RNA 1 (dsRNA 4) of BbBV1 is 2,026 bp in length, encoding a RNA-dependent RNA polymerase (RdRp) (68.54 kDa), while the RNA 2 (dsRNA 6) is 1,810 bp in length, encoding a hypothetical protein (35.55 kDa) with unknown function. Moreover, the amino acid sequence of RdRp showed the highest sequence identity of 62.31% to Botryosphaeria dothidea bipartite mycovirus 1. Phylogenetic analysis based on RdRp sequences revealed that BbBV1 represents a distinct lineage of unassigned dsRNA mycoviruses infecting fungi.