Complete nucleotide sequence of an isolate of coleus vein necrosis virus from verbena

Molecular characterization of two recombinant isolates of telosma mosaic virus infecting Passiflora edulis from Fujian Province in China

Telosma mosaic virus (TeMV) is an important plant virus causing considerable economic losses to passion fruit (Passiflora edulis) production worldwide, including China. In this study, the complete genome sequence (excluding the poly (A) tail) of two TeMV isolates, Fuzhou and Wuyishan, were determined to be 10,050 and 10,057 nucleotides, respectively. Sequence analysis indicated that Fuzhou and Wuyishan isolates share 78-98% nucleotide and 83-99% amino acid sequence identities with two TeMV isolates of Hanoi and GX, and a proposed new potyvirus, tentatively named PasFru. Phylogenetic analysis indicated that these TeMV isolates and PasFru were clustered into a monophyletic clade with high confidences. This indicated that PasFru and the four TeMV isolates should be considered as one potyvirus species. Two recombination breakpoints were identified within the CI and NIb genes of the Fuzhou isolate, and also within the P1 gene of the Wuyishan isolate. To the best of our knowledge, this is the first report of TeMV recombinants worldwide.

The complete sequence and genome organization of ligustrum virus A, a novel carlavirus

The complete genome sequence of ligustrum virus A (LVA) from a Ligustrum obtusifolium Sieb. & Zucc. plant was determined. The genomic RNA has 8,525 nucleotides, excluding the poly(A) tail, and consists of six open reading frames typical of members of the genus Carlavirus, family Betaflexiviridae. Phylogenetic analysis of the viral replicase and coat protein (CP) indicated that LVA is closely related to daphne virus S and helenium virus. The replicase and CP of LVA shared 44.73-52.35 % and 25.39-62.46 % amino acid identity, respectively, with those of other carlaviruses. These results suggest that LVA is a member of a distinct carlavirus species.

Genomic sequence analysis of four new chrysanthemum virus B isolates: evidence of RNA recombination

Chrysanthemums worldwide suffer from a high incidence of infection with chrysanthemum virus B (CVB), a member of the genus Carlavirus, family Betaflexiviridae. Three major lineages or strains of this virus have been found in India, but none have been characterized beyond the genetic variation they display in their coat protein genes. Here, we describe the analysis of four near-complete genome sequences (from the three lineages) representing the genetic diversity of these strains. Ranging in size from 8815 to 8855 nucleotides (excluding the polyA tail), these four isolates have a genome organization very similar to that of the recently reported Japanese isolate of CVB, with which they share between 70 and 73% genome-wide sequence identity. We present further evidence that recombination may feature quite prominently in the evolution of CVB.

A New Potyvirus sp. Infects Verbena Exhibiting Leaf Mottling Symptoms

Verbena 'Taylortown Red' plants showed virus-like mottling symptoms. Virus purifications disclosed the presence of elongated and spherical particles, evidence of mixed virus infections, whereas double-stranded RNA analysis revealed the presence of several bands absent in healthy plants. After shotgun cloning, three viruses were identified in 'Taylortown Red': Broad bean wilt virus-1, Coleus vein necrosis virus, and a previously undescribed potyvirus. Given the importance of verbena to the ornamental industry, we studied the viruses found in 'Taylortown Red' and, in this article, we present our findings on the new potyvirus, provisionally named Verbena virus Y (VVY). VVY belongs to the Potato virus Y subgroup in the genus Potyvirus, has solanaceous plants, including potato, as alternative hosts, and can be transmitted by a ubiquitous pest in the ornamental industry, the green peach aphid.

A new method for extraction of double-stranded RNA from plants

The occurrence of high molecular weight double-stranded RNA (dsRNA) in plants is associated with the presence of RNA viruses. DsRNA is stable, can be extracted easily from the majority of plant species and provides an excellent tool for characterization of novel viruses that are recalcitrant to purification. Several protocols have been developed for dsRNA purification, the majority of which are based on extraction with phenol and chloroform. We have developed a protocol for dsRNA extraction based on a lithium salts buffer that does not require organic solvents other than alcohols. The method yields comparable amount of dsRNA to protocols described previously and yields consistently dsRNA from Vaccinium hosts that have been recalcitrant to dsRNA purification using traditional protocols. The quality of the dsRNA purified is such that it can be used for downstream enzymatic reactions including reverse transcription-polymerase chain reaction and cloning.