A novel emaravirus comprising five RNA segments is associated with the ringspot disease in oak. novel emaravirus in ringspot diseased oak

We report the discovery of a new viral disease affecting the Common oak (Quercus robur L.), which is associated with symptoms such as mottle, chlorotic spots and ringspots on diseased trees. High-throughput sequencing (HTS, Illumina RNASeq) was used to explore the virome of a diseased oak showing chlorotic ringspots of suspected viral origin on leaves for several years. We identified four genome segments of a virus showing high similarity to members of the genus Emaravirus were, which comprises segmented negative stranded RNA viruses of economic impact. To verify the accurate ends of each RNA, we conducted RACE analysis. We identified an additional genome segment (RNA 5) was by RT-PCR using a genus-specific primer (PDAP213) to conserved 3´- and 5´-termini in order to amplify full-length genome segments. RNA5 encodes a 21 kDa protein homologous to the silencing suppressor P8 of High plains wheat mosaic virus, a member of group III emaraviruses. We found homologs of this 21 kD protein in most other members of group III emaraviruses. RT-PCRs consistently detected the five viral RNAs, confirming the presence of the virus in ringspot diseased oaks in Germany, Sweden and Norway. We conclude that the virus represents a new member of the genus Emaravirus affecting oaks in Germany and in Scandinavia. We propose the name common oak ringspot-associated emaravirus (CORaV).