First report of Pepper chat fruit viroid in capsicum pepper in Canada

In the summer of 2009 in a greenhouse in the south of Ontario, Canada, up to 3% of the plants of the pepper cvs. Score and Lamborgini (Capsicum annuum) showed mild growth reduction and abnormally small fruits (Fig. 1). Symptoms were observed spreading along the rows. These observations suggested the presence of Pepper chat fruit viroid (PCFVd), a viroid recently described infecting capsicum pepper in the Netherlands (Verhoeven et al., 2009). For diagnosis, two small-sized pepper fruits of cultivar Lamborgini were sent by the grower to the Plant Protection Service of the Netherlands. The fruits were tested in a single sample by reverse transcription polymerase chain reaction (RT-PCR) with primer pairs Pospi1-RE/FW (Verhoeven et al., 2004) and AP-FW1/RE2 (Verhoeven et al., 2009), which produced amplicons of 193 and 335 bp for PCFVd, respectively. The complete viroid genome of 348 nt was derived from overlapping sequence fragments, after directly sequencing RT-PCR products (GenBank Accession No. HQ731652). BLAST analysis of the obtained sequence showed a 100% of sequence identity to that of the PCFVd isolate from the Netherlands (FJ409044) (Verhoeven et al., 2009). In addition, the Canadian isolate was mechanically inoculated to young plants, four each for capsicum pepper cv. Yolo Wonder and tomato (Solanum lycopersicum) cv. Moneymaker. The tomato plants developed symptoms after four weeks of inoculation, including chlorosis and stunting, whereas no symptoms were observed on the post-inoculated pepper plants. After six weeks, the presence of the viroid in the post-inoculated plants was confirmed for both plant species by RT-PCR with primers Pospi1-RE/FW in bulked samples of four plants.

Although PCFVd may be transmitted through capsicum pepper seed, a direct relationship between the outbreaks in Canada and the Netherlands seems unlikely as different cultivars from different seed companies were involved (Verhoeven et al., 2009). Symptomless infected ornamental host plants may have been the source of infection of pepper plants in the Ontario greenhouse, as reported for the Potato spindle tuber viroid in tomato. Thus ornamentals may pose a phytosanitary risk for vegetable crops (Navarro et al., 2009; Verhoeven et al., 2010). The grower was encouraged to notify the Canadian phytosanitary authorities of these findings.