Identification of Cucumber mosaic virus isolate from Passiflora edulis in Southern Italy and validation of subgroup identification by in silico RFLP.

Reverse transcription-polymerase chain reaction (RT-PCR), comparison of nucleotide sequences and in silico restriction enzyme analysis were used to identify for the first time in Italy an isolate of Cucumber mosaic virus (CMV), belonging to subgroup II, from a disease-affected passion fruit (Passiffora edulis) plant. We showed also that CMV sequences obtained by RT-PCR with primers designed to a conserved region of the 3' end of the CMV coat protein gene, combined with computer-based restriction analysis of sequences stored in databases, can be a very powerful method for identification or validation for CMV subgroups. An accurate disease diagnosis requires reliability, high reproducibility and high throughput of the chosen method. With the proposed in silico approach, we managed to identify and validate with safety the identification of the three CMV subgroups (IA, IB and II). Isolates of CMV can be reliably identified by this method and thus it should be considered as a powerful tool for both epidemiological and management aspects of the CMV-plant interactions. The potentialities of this diagnostic method are discussed and compared with those of conventional methods.