Natural infection by Cucumber mosaic virus (Cucumovirus; Bromoviridae) in Fuchsia boliviana Carr and the insusceptibility of other Fuchsia species and hybrids to the virus.

Only the carlavirus Fuchsia latent virus (Dellavalle et al., 1996) and the tospovirus Tomato spotted wilt virus (Tehrani et al., 1990; Louro 1996) have been reported to occur naturally in some Fuchsia spp. and hybrids. In May 1999, some plants of F. boliviana in a private garden on the Italian Riviera close to Sanremo had leaves with a severe mosaic (Figure 1). In August 1999, similar symptoms were observed on the same species in the Montet botanic garden (Nancy, France). At both places, other Fuchsia species and hybrids grown close to F. boliviana appeared to be healthy. From symptomatic plants from both locations, Cucumber mosaic virus (CMV) was easily sap-transmitted to several experimental hosts of the virus.

Both isolates were typed as Subgroup II by ELISA using an AGDIA (Elkhart, IN, USA) kit based on specific monoclonal antibodies. No other viruses were seen in sap of infected plants by electron microscopy. The Italian isolate was multiplied in tobacco and then mechanically-inoculated to the following Fuchsia species: F. magellanica Lamark, F. regia Vandeli, F. skutkiana Munz, and F. thymifolia Kris and the following commercial Fuchsia hybrids provided by Lazzeri Company (Italy): Aello, Ilaria, Irene, Rilly, Sonia and Tyrol. After two months, no symptoms appeared and the virus was not detected in either inoculated or uninoculated leaves by ELISA. Our field observations and experimental tests, apparently indicate that only F. boliviana is susceptible to CMV. This suggests that this species should not be used for breeding to prevent accidental introduction of susceptibility into new hybrids.