Genome characterization of a novel betaflexivirus from the wild tea plant Camellia taliensis.

The wild tea species Camellia taliensis is an important genetic resource and a close relative of cultivated tea plants. In this study, metatranscriptomic sequencing of asymptomatic leaves of C. taliensis led to the identification of a previously undescribed virus. This virus, which is tentatively named as Camellia taliensis betaflexivirus 1 (CtBV1), possesses a monopartite positive-sense RNA genome of 6,564 nucleotides (nt). The genome contains two overlapping open reading frames (ORFs), flanked by a 37-nt 5′ untranslated region (UTR) and a 128-nt 3′ UTR. The larger ORF encodes a polyprotein containing conserved domains typical of members of the family Betaflexiviridae, including viral methyltransferase, RNA helicase, RNA-dependent RNA polymerase, and coat protein. Phylogenetic analysis based on the replication-associated protein placed CtBV1 in a clade with viruses belonging to the genus Capillovirus, including apple stem grooving virus and cherry virus A. Pairwise amino acid sequence comparisons showed that CtBV1 shares less than 80% identity with these viruses in the replication-associated protein, supporting the classification of CtBV1 as a novel species within the family Betaflexiviridae. The discovery of CtBV1 expands the currently known diversity of viruses associated with Camellia species and provides new information on viruses infecting wild tea germplasm.