Conserved carlavirus and potyvirus primers were used in reverse transcriptase‐polymerase chain reaction (RT‐PCR) to amplify virus fragments from Chinese narcissus (Narcissus tazetta var. chinensis) in China and the fragments were subsequently sequenced and compared in phylogenetic analyses. Samples from Fujiang province and Shanghai contained either one or two potyviruses and a carlavirus. One potyvirus (PY1) showed a distant relationship to Iris severe mosaic virus, Onion yellow dwarf virus and Shallot yellow stripe virus, while the other (only in the Fujiang sample, PY2) was most closely related to Turnip mosaic virus (TuMV). Similar experiments using glasshouse grown Narcissus originating from the UK contained Ornithogalum mosaic virus and another potyvirus (PY3) in the TuMV/PY2 cluster. Comparisons with previously determined sequence fragments indicated that PY2 was probably Narcissus yellow stripe virus and PY3 Narcissus late season yellow virus. Carlavirus fragments from both Chinese sites seemed to be of the same virus, which was most closely related in phylogenetic analyses to Potato virus M, Aconitum latent virus and Hop latent virus. It is most probably a new member of the genus Carlavirus and has been tentatively named Narcissus common latent virus.
The complete nucleotide sequence of an isolate of Ribgrass mosaic virus (RMV-Sh) from Brassica chinensis (Qingcai) in Shanghai, China was determined. The genome consisted of 6301 nucleotides and its genomic organization was similar to those of other crucifer-tobamoviruses. Comparisons of the nucleotide and predicted amino acid sequences and phylogenetic analyses showed that RMV-Sh had very high homology (> 95% identical nucleotides and 97.7-99.6% identical amino acids) to a sequence of Youcai mosaic virus (YMV = Chinese rape mosaic or Oilseed rape mosaic virus), despite differences in host range or symptoms and this strongly suggests that these isolates should be regarded as belonging to the same species. Only coat protein sequences have been reported for other RMV isolates but it seems likely that the distinction between RMV and YoMV will be difficult to maintain.
The complete sequence of an isolate of Narcissus common latent virus (NCLV) from Zhangzhou city, Fujian, China was determined from amplified fragments of purified viral RNA. Excluding the poly(A) tail, the genomic RNA of NCLV was 8539 nucleotides (nt) long and had the typical organization for a member of the genus Carlavirus. The most closely related species were Potato virus M, Hop latent virus and Aconitum latent virus, which had 58-59% nt identity to NCLV in their entire genomes. These relationships were confirmed by a phylogenetic analysis using a composite nucleotide alignment of all the open reading frames.
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