First report of Colombian datura virus from Australia

Brugmansia sp. (Angel’s trumpet; Family: Solanaceae) is a shrub or small tree with flowers that are single, pendent, trumpet-like or funnel-shaped to 30 cm long. Originally from South America, it is used mainly as a houseplant or for landscaping (Russell et al. 1997). In 1968, a virus named Colombian datura virus (CDV, genus Potyvirus) was reported from plants of B. (syn. Datura) candida and B. (syn. Datura) sanguinea originating from Colombia (Kahn and Bartels 1968). The virus has subsequently been reported from Europe, Japan, Canada and the USA in a range of hosts including tomato, pepino, tobacco, cape gooseberry, petunia, the terrestrial orchid Spiranthes ceruna and Brugmansia spp. (Fry et al. 2004; Schubert et al. 2006; Rott et al. 2009).

In 2007, a sample of Brugmansia sp. from Bomaderry, New South Wales, Australia was submitted for disease diagnosis. The sample displayed a chlorotic mosaic pattern (Fig. 1) and flexuous filamentous virus-like particles were observed by electron microscopy of a sap preparation (Fig. 2). The particles were estimated to have a mean length of 836 ± 23 nm (42 particles measured), using Tomato mosaic virus as an internal size standard (300 nm × 18 nm; Thomas 1985).

Symptomatic leaves of the Brugmansia sp. sample were used for the mechanical inoculation of a range of test plants and symptoms were recorded after 15 days (Table 1). All inoculated species showed local and/or systemic symptoms, except for Capsicum annuum cv. Yolo Wonder, and were generally consistent with those previously reported for CDV (Kahn and Bartels 1968; Verhoeven et al. 1996; Fry et al. 2004). A random sample of all symptomatic species and the 15 symptomless Yolo Wonder plants were indexed by antigen-coated plate enzyme-linked immunosorbent assay. This was done by using a potyvirus group antibody kit (SRA 27200, Agdia Inc., Elkhart, IN, USA) essentially following the manufacturer’s instructions. All symptomatic plants were positive for potyvirus. All the Yolo wonder plants were negative, except two which gave borderline results. These latter two plants were shown to be uninfected by back-inoculation onto Nicotiana tabacum cv. Xanthi nc.

Table 1.  Reaction of mechanically inoculated test plants to Columbian datura virus infection

Total RNA was extracted from the Brugmansia leaves using an RNeasy Plant Mini Kit (QIAGEN, Hilden, Germany) following the manufacturer’s instructions. The RNA was eluted from the spin column using 50 μL of RNase-free water. A reverse transcription polymerase chain reaction (RT–PCR) was done using degenerate potyvirus primers U341 (Langeveld et al. 1991) and poty 1 (Gibbs and Mackenzie 1997). The ≈720 bp DNA fragment (Fig. 3) was excised from the agarose gel, cloned and sequenced as described by Schwinghamer et al. (2007). The consensus sequence of 684 nt from three independent clones was lodged on GenBank (FJ821796) and covered the 3′ portion of the coat protein coding region and the 3′ untranslated region (UTR). It was 99.4–99.6% identical to CDV (GenBank accessions AM113754, AM113757 and AY621656). When translated, the sequence of the 3′ 147 amino acids of the coat protein was found to be 100% identical, and the nt sequence of the 3′UTR 99.6–100% identical to these same CDV isolates.

This report represents the first record of CDV from Australia. As CDV can also infect tomato and potato, it may constitute a threat to these crops. The Australian Brugmansia isolate is stored in the QPIF Indooroopilly Plant Virus Collection as virus isolate number 2079.