Diagnosis of Broad bean wilt virus 1 and Verbena latent virus in Tropaeolum majus in New Zealand.
A Tropaeolum majus (nasturtium) plant with severe leaf mosaic symptoms was collected from a public park in New Zealand in September 2004. Electron microscopy of crude sap preparations revealed the presence of flexuous filamentous virus particles of different sizes. Necrotic local lesions followed by systemic leaf necrosis, chlorosis, mosaic or distortion developed on nine species of herbaceous indicator plants. The original sample and indicator plants tested positive for Broad bean wilt virus 1 (BBWV-1, genus Fabavirus) and Verbena latent virus (VeLV, genus Carlavirus) by enzyme-linked immunosorbent assay (ELISA). BBWV-1 was confirmed by reverse transcription-polymerase chain reaction (RT-PCR) using generic fabavirus primers and specific BBWV-1 primers. A RT-PCR using specific primers to VeLV was developed. The BBWV-1 and VeLV amplicons each showed 96% nucleotide identity to published sequences of BBWV-1 isolate PV-132 (New York, USA) and VeLV from Israel, respectively. The sample was also coinfected with Turnip mosaic virus (genus Potyvirus) and Opium poppy mosaic virus (unassigned member of the genus Umbravirus). This is the first report of BBWV-1 in New Zealand and the first report of VeLV infecting T. majus worldwide. T. majus is a common weed in New Zealand and may represent a significant reservoir for these viruses.