Characterization of a novel double-stranded RNA mycovirus conferring hypovirulence from the phytopathogenic fungus Botryosphaeria dothidea

- Mycoviruses have been described in many fungal species. Here, the biological and molecular features of a novel dsRNA virus, BdRV1, are described.
- This dsRNA virus was isolated from a hypovirulent strain of Botryosphaeria dothidea. It is here asserted that BdRV1 confers hypovirulence.
- The proteins encoded by dsRNA1-4 shared significant amino acid identities of 55%, 47%, 43% and 53% with the corresponding proteins of Aspergillus fumigatus tetramycovirus-1(AfuTmV1).
- BdRV1 together with AfuTmV1 will constitute a possibly new mycovirus family. BdRV1 may be able to be transfected in the form of unusual ribonucleoprotein (genomic dsRNA+dsRNA4-coded P-A-S rich protein) as in the case of AfuTmV1.
- BdRV1 is able to confer hypovirulence to the fungal host and to be transmitted 100% via asexual sporulation. This provides the virus with biological control potential.

A novel double-stranded RNA (dsRNA) virus, designated as Botryosphaeria dothidea RNA virus 1 (BdRV1), isolated from a hypovirulent strain YZN115 of Botryosphaeria dothidea was biologically and molecularly characterized. The genome of BdRV1 comprises of five dsRNAs. Each dsRNA contains a single open reading frame. The proteins encoded by dsRNA1-4 shared significant amino acid identities of 55%, 47%, 43% and 53% with the corresponding proteins of Aspergillus fumigatus tetramycovirus-1. DsRNA1, 3, and 4 of BdRV1 encoded an RNA-dependent RNA polymerase, a viral methyltransferase, and a P-A-S-rich protein, respectively. Function of proteins encoded by the dsRNA2 and dsRNA5 were unknown. BdRV1 conferred hypovirulence for its host and could be transmitted through conidia and hyphae contact.