First report of Wisteria vein mosaic virus in China

Wisteria mosaic is a common disease of Wisteria spp. in many regions of China. According to a recent survey, the incidence of this disease was about 40% on ornamental wisteria (including W. sinensis and W. floribunda) in gardens and courtyards in the Beijing area. In the most severely affected areas, about 80% disease incidence was recorded.

In 2002, mosaic symptoms on W. sinensis were found on the west campus of China Agricultural University in Beijing. The symptoms included flecking, yellowing, vein clearing, mottling or mosaic on the leaves; similar to those of wisteria mosaic disease reported in other countries (Bos, 1970; Conti & Lovisolo, 1970; Clover et al., 2003). The virus was mechanically transmitted to Chenopodium amaranticolor and C. quinoa, producing local chlorotic lesions and systemic chlorotic lesions, respectively. It was also transmitted to Nicotiana clevelandii, causing systemic mild chlorotic lesions, and to Vicia faba, producing systemic chlorotic lesions. This virus isolate was found to be serologically related to some potyviruses such as Bean common mosaic virus (BCMV) and Watermelon mosaic virus. The results of DAS-ELISA tests using polyclonal antiserum against BCMV were consistent with the observations of symptoms. Typical potyvirus pinwheel inclusion bodies were found in the cytoplasm of infected W. sinensis leaves.

The 3′-partial nucleotide sequence, including the putative CP-coding region and the 3′-nontranslated region (NTR), of the Beijing isolate has been determined (accession number AY519365). The CP was composed of 282 amino acids and the 3′-NTR was 252 nucleotides long excluding the stop codon and the polyadenylated tract. A BLAST search of the sequence revealed that it was most closely related to Wisteria vein mosaic virus (WVMV) (accession number AF484549). Comparison of the deduced CP amino acid sequences between the Beijing isolate and that from New Zealand showed 96% similarity. The 3′-NTR sequence similarity for the two isolates was 90%. According to the current virus species demarcation standard for the genus Potyvirus in the family Potyviridae (van Regenmortel et al., 2000), the virus isolated from W. sinensis in Beijing definitely belongs to WVMV. This is the first report of the occurrence of WVMV in China.