First report of cucumber vein yellowing virus in melon in France

During the fall of 2003, mild mosaic symptoms were observed in melon (Cucumis melo L.) plants grown in glasshouses near Eyragues (southeastern France) resembling those caused by the Bemisia tabaci transmitted Cucumber vein yellowing virus (CVYV, genus Ipomovirus, family Potyviridae). In addition, large numbers of B. tabaci were observed to be colonizing these crops. The identification of CVYV was established through differential host range reaction, immunosorbent electron microscopy (IEM), and reverse transcription (RT)-PCR experiments. Crude sap from symptomatic leaves was used to inoculate differential host plants. Mild mosaic symptoms were observed on melon, and cucumber developed vein-clearing symptoms typical of CVYV. No symptoms were observed in Chenopodium quinoa, C. amaranticolor, Nicotiana benthamiana, N. tabacum, and Vigna sinensis. Numerous, slightly flexuous, elongated virus particles were observed in infected plant extracts; these particles were decorated by a polyclonal antiserum raised against a Sudanese CVYV isolate. To confirm CVYV identification, total RNA extracts (TRI-Reagent, Sigma Chemical, St. Louis, MO) were obtained from the original symptomatic melon tissues. RT-PCR was carried out using CVYV-specific primers CVYV-CP-5′: 5′-GCTTCTGGTTCTCAAGTGGA-3′ and CVYV-CP- 3′: 5′-GATGCATCAGTTGTCAGATG-3′ designed according to the partial sequence of the coat protein gene of CVYV-Isr (GenBank Accession No. AF233429) (2). A 540-bp fragment corresponding to the central region of CVYV coat protein was amplified from total RNA extracted from symptomatic but not from asymptomatic melon tissue. Direct sequencing was done on RT-PCR products (GenBank Accession No. EF441272). The sequence was 95 and 99% identical to that reported for CVYV isolates from Israel and Spain, respectively. CVYV was first described in Israel and has recently emerged as the cause of important diseases in Spain and Portugal (1,3). Shortly after detecting CVYV during 2003, efforts were made to eradicate the virus in susceptible crops. CVYV was not detected again during intensive surveys conducted in southeastern France during 2004, 2005, and 2006, suggesting that the CVYV detected during 2003 resulted from an accidental introduction and that the virus has not become established in France