RESUMO
The complete genome sequence of a new virus infecting yam plants exhibiting mosaic symptom in Brazil was determined. The genome of this virus is composed of two molecules of positive-sense RNAs of 5979 and 3809 nucleotides in length, excluding the poly(A) tails. One large open reading frame (ORF) in each genomic segment (RNA1-ORF1 and RNA2-ORF2) was predicted. The highest amino acid sequence similarity in the Pro-Pol core region of RNA1 and the CP region of RNA2 was observed with chocolate lily virus A (a putative member of the family Secoviridae), with 54.6 and 27.7 % identity, respectively. This virus is thus likely to be a new member of the family Secoviridae, and we propose the tentative name "dioscorea mosaic-associated virus" (DMaV) for this virus.
Assuntos
Dioscorea/virologia , Genoma Viral , Vírus de Plantas/isolamento & purificação , Vírus de RNA/isolamento & purificação , RNA Viral/genética , Análise de Sequência de DNA , Brasil , Análise por Conglomerados , Fases de Leitura Aberta , Filogenia , Doenças das Plantas/virologia , Vírus de Plantas/classificação , Vírus de Plantas/genética , Vírus de RNA/classificação , Vírus de RNA/genética , Homologia de Sequência de AminoácidosRESUMO
The complete genome of a tymovirus infecting Solanum violaefolium was sequenced. The genome comprised 6284 nt, with a 5'-UTR of 137 nt and a comparatively longer 3'-UTR of 121 nt. Sequence analysis confirmed three ORFs encoding a movement protein, a polyprotein, and a coat protein (CP). The isolate was considered to be the Tomato blistering mosaic virus (ToBMV) based on a CP amino acid sequence identity of 95.3 %. The nucleotide sequence of the complete genome of the S. violaefolium isolate, however, differed markedly from the other two reported ToBMV isolates, with identities of 76.6 and 76.3 %, below one of the demarcation criteria of the genus Tymovirus (overall genome identity of 80 %). No recombination signals were detected in the genome of this isolate. The high identity of the CP amino acid sequence and similar host responses suggest that the S. violaefolium isolate belongs to the same species as the Tomato blistering mosaic virus. The sequence analysis of this ToBMV isolate thus suggests that the demarcation criterion of 80 % overall genome sequence identity in the genus Tymovirus may require revision.