First report of Broad bean wilt virus 1 in Slovenia

During the summer of 2006, pepper plants (Capsicum annuum L) cvs. Atol, Olimpus, Bjanca and Verbrana, showing virus-like symptoms, were observed in a commercial field in SE Slovenia. Discolorations, rings or dark bumps on fruits (Fig. 1) resulted in almost a 100% loss of the yield in some areas. Symptoms on leaves were expressed as arabesques or concentric rings (Fig. 2). In autumn, infected plants expressed less severe symptoms and produced symptomless fruits.

Infected leaves and fruits, with various symptoms, were tested by ELISA for the presence of BBWV 1 (Broad bean wilt virus 1), BBWV 2 (Broad bean wilt virus 2), CSNV (Chrysanthemum stem necrosis virus), CMV (Cucumber mosaic virus), INSV (Impatiens necrotic spot virus) and TSWV (Tomato spotted wilt virus). Positive results were obtained only for BBWV 1 in all samples collected from the epidemic area. Immuno-serological electron microscopy (ISEM) (antibodies from DSMZ, Germany) of crude sap extracts confirmed BBWV 1 infection. RT-PCR using BBWV 1 specific primers B1/B2 (Rubio et al., 2002) produced an amplicon of approximately the expected size (500 bp) from extracts from infected but not healthy plants.

The sequence of the amplicon was determined (GenBank accession number EF405826). BLAST analysis of a 334 bp segment, encompassing part of the two coat proteins genes, showed approximately 80% nt identity with various BBWV 1 isolates. Amino acid identities ranged from 90 to 92% with BBWV 1 isolates and from 54 to 58% with BBWV 2 isolates. Sap of symptomatic plants was used for mechanical inoculation of test plants. Local and systemic symptoms were observed on pepper, Chenopodium quinoa, Nicotiana rustica, and N. tabacum cv. White Burley. No symptoms were observed on N. clevelandii, N.benthamiana and Lycopersicon esculentum. BBWV 1 was also identified in one out of 6 weed species belonging to the family Cichoriaceae, expressing mild mosaic symptoms and growing near the epidemic area. To our knowledge this is the first report of BBWV 1 in Slovenia.