First Report of Anemone Plants Infected by Ranunculus white mottle virus.

Ranunculus white mottle virus (RWMV) (1), genus Ophiovirus, has been reported in crops of several cultivars of commercial ranunculus (Ranunculus asiaticus hybrids) during the 1990s in Liguria in Northwest Italy. Symptoms associated with RWMV in ranunculus are not clear-cut owing to the presence of mixed viral infections. During autumn 1999, a severe disease in commercial crops of anemone (Anemone coronaria) was noted in the same area. Plants appeared stunted with young leaves showing curling, deformation, and necrotic spotting. Disease incidence in some fields reached 40 to 50%. DAS- and TAS-enzyme-linked immunosorbent assays (ELISAs) for presence of RWMV and for the viruses most frequently infecting anemone in Italy were run on 24 field samples. Seven proved to be infected by RWMV in mixed infection with Cucumber mosaic virus subgroup II or with Tobacco necrosis virus. Ophiovirus-like particles were detected by negative staining and electron microscopy from sap extracts of field plants that were RWMV-positive by ELISA. Sap from these plants was also mechanically inoculated to indicator plants. Total RNAs were extracted from RWMV-infected field samples and from inoculated Nicotiana benthamiana and N. clevelandii and used in molecular tests. A DIG-DNA probe targeting the 1.8-kb RNA2 of RWMV was used in Northern blots and dot blots of total RNAs, confirming the infection in field samples and multiplication of the virus in test plants, unfortunately still in mixed infection. At present, it is difficult to evaluate RWMV symptomatology in anemone, but the presence of this virus in mixed infection seems to produce serious effects. This is the first report of RWMV in anemone. Reference: (1) A. M. Vaira et al. Arch. Virol. 142:2131, 1997.