R.A. Mumford*, B. Jarvis, J. Morris and A. Blockley

*r.mumford@csl.gov.uk

Accepted for publication 05/03/03

In November 2002, samples were received from an all-year-round chrysanthemum crop growing under glass in South West England. The crop consisted of cvs Fiji and Calabria, cuttings of which originated from Brazil. The samples had distinct dark stem lesions (Fig. 1) and some leaf necrosis. Given these symptoms and the absence of any fungal pathogens, the plants were tested by ELISA for the presence of three tospoviruses. Chrysanthemum stem necrosis virus (CSNV) was detected using a polyclonal DAS-ELISA kit (DSMZ, Germany). Neither Tomato spotted wilt virus nor Impatiens necrotic spot virus were detected. When examined electron microscopically, sap from the samples was found to contain spherical tospovirus-like virus particles of 90 to 110 nm in diameter. Mechanical inoculation of sap from symptomatic stem material to a range of indicator plant species resulted in symptoms typical of CSNV (Bezerra et al., 1999), including systemic mosaic in Nicotiana benthamiana; these symptomatic indicator plants tested positive for CSNV when tested by ELISA. RT-PCR using degenerate tospovirus primers BR60 and BR65 (Eiras et al., 2001) was also performed on extracts taken from symptomatic stem tissue and a single product of the correct predicted size (453 bp) was obtained; this product was sequenced and shown to share 98% identity with the 5' end of the capsid protein gene of a published CSNV sequence (AF067068).

Figure 1. Necrotic lesions on the stem of a CSNV-infected chrysanthemum plant, variety 'Fiji'

The infected crop has now been removed and measures taken to eradicate the infection. As CSNV has previously been reported only from Brazil and the Netherlands (Bezerra et al., 1999; Verhoeven et al., 1996), this is the first report of its occurrence in the UK.

Bezerra IC, Resende R de O, Pozzer L, Nagata T, Kormelink R, de Avila AC, 1999. Increase of tospoviral diversity in Brazil with the identification of two new tospovirus species, one from chrysanthemum and one from zucchini. Phytopathology 89, 823-830.

Eiras M, Resende RdeO, Missiaggia AA, de Avila AC, 2001. RT-PCR and dot blot hybridisation methods for a universal detection of tospoviruses. Fitopatologia Brasileira 26, 170-175.

Verhoeven, JTJ, Roenhorst JW, Cortes I, Peters D, 1996. Detection of a novel tospovirus in chrysanthemum. Acta Horticulturae 432, 44-51.

The British Society for Plant Pathology