First report of pospiviroids infecting ornamentals in the Netherlands: Citrus exocortis viroid in Verbena sp., Potato spindle tuber viroid in Brugmansia suaveolens and Solanum jasminoides,and Tomato api

In order to investigate the viroid status of ornamental plants in the Netherlands, a survey was carried out in 2006. A total of 62 samples were taken at 31 nurseries, with each sample consisting of young leaves taken from five randomly chosen plants per lot. Most samples were taken from ornamental plants belonging to the families Gesneriaceae and Solanaceae. In addition, another 50 samples from ornamental plants, submitted for virus diagnosis, were also tested for pospiviroids. The first screening was by reverse transcription-polymerase chain reaction (RT-PCR) with two sets of semi-universal pospiviroid primers i.e. Pospi1-RE/FW and Vid-RE/FW (Verhoeven et al., 2004), yielding amplicons of approximately 196 (partial) and 360 nt (full length), respectively. PCR products were sequenced and analysed for initial identification of any viroids detected. Definite identification was based on sequence analysis of full-length amplicons, generated by RT-PCR using primers 3H1/2H1 (Shamloul et al., 1997) for Potato spindle tuber viroid (PSTVd) or primers CEVd-FW/RE (�nelge et al., 1997) for both Tomato apical stunt viroid (TASVd) and Citrus exocortis viroid (CEVd).

Although none of the ornamental hosts showed any symptoms, several samples tested positive for viroid infection. The following viroids were identified: CEVd in Verbena sp., PSTVd in Brugmansia suaveolens and Solanum jasminoides and TASVd in Cestrum sp. The nucleotide sequences were submitted to GenBank, with the accession numbers EF192396, EF192394, EF192393 and EF192395, respectively. Initial pathogenicity studies showed infection of tomato after mechanical inoculations in a greenhouse under quarantine conditions.

To our knowledge this is the first report of PSTVd in Brugmansia suaveolens and S. jasminoides,and of TASVd in Cestrum sp. CEVd infections in Verbena hybrida have recently been reported in India (Singh & Dilworth, 2006), but this is the first report from Europe. At this moment the process of tracing back the origins of infection is still ongoing. Control measures have been applied, including eradication of infected lots and countries that are likely to have received infected plant material have been informed.