Complete genome sequence of a novel double-stranded RNA virus infecting the phytopathogenic fungus Rhizopus stolonifer.

In this study, we report the complete genome sequence of a novel toti-like virus, tentatively named "Rhizopus stolonifer double-stranded RNA virus 1" (RsDSV1), identified from a phytopathogenic fungal agent of apple fruit rot disease, Rhizopus stolonifer strain A2-1. RsDSV1 has a double-stranded RNA genome. The complete RsDSV1 genome is 5178 nucleotides (nt) in length and contains two open reading frames (ORFs) encoding a putative coat protein (CP) and an RNA-dependent RNA polymerase (RdRp). Phylogenetic analysis based on RdRp and CP amino acid sequences revealed that RsDSV1 is closely related to unclassified members of the family Totiviridae. In stress-inducing Vogel's minimal and sodium dodecyl sulfate-containing media, hyphal growth of A2-1 was suppressed, but the accumulation of RsDSV1 RNA increased, indicating that stresses promote RsDSV1 replication. To our knowledge, this is the first report of a mycovirus found in R. stolonifer.