TOBACCO STREAK VIRUS INFECTING BUXUS SEMPERVIRENS
In Autumn 2001, three pot plants of box-tree (Buxus sempervirens) from Tuscany region (central Italy) were sent to DiSTA-Plant Pathology of the Bologna University to be examined for virus presence. These plants showed severe virus-like symptoms such as yellow mosaic and chlorotic stripes on the leaves; in addition, the symptomatic box-trees looked less vigorous and severely stunted. In initial trials a small number of test plants were sap-inoculated with juice of symptomatic leaves. Only Vigna sinensis Black eye and Nicotiana benthamiana developed symptoms that were used as starting material for virus identification. In host range tests, plants of 26 species (belonging to 10 botanical families) were inoculated and 11 of them were infected. In particular, Solanaceae and Cucurbitaceae showed symptoms similar to those described for the type strain of Tobacco streak virus (TSV). Cucumis sativus Marketer showed local necrotic rings; Nicotiana glutinosa, N. tabacum Samsun and White Burley, displayed local whitish necrotic ringspots, line-patterns and oak-leaf patterns. The observations of leaf-dip preparations from inoculated host plants and original box-tree material, carried out under a Philips CM 10 electron microscope, did not reveal the presence of elongated virus-like particles. Immuno-electron microscopy tests (ISEM) were applied to crude sap from infected herbaceous plants, by using the antisera to several bacilliform and spherical viruses, including that to TSV and TSV-Gladiolus sp. The use of these antisera revealed the presence of strongly decorated spherical virus particles; no other viruses were found. In 2003, some symptomless box-trees (provided by a commercial grower and previously tested negative for TSV presence) were grafted with shoots from box-tree showing yellow mosaic on the leaves and maintained in a greenhouse under aphid proof-cage. After about one year, one grafted-plant showed chlorotic stripes on the leaves. To our knowledge, this is the first report of TSV infection in box-tree.
Bellardi, M.G., Sghedoni, L. and Bertaccini, A. (2006). TOBACCO STREAK VIRUS INFECTING BUXUS SEMPERVIRENS. Acta Hortic. 722, 229-234
box-tree, symptoms, TSV, diagnosis