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Occurrence of Cucumber vein yellowing virus in cucurbitaceous species in southern Portugal

D. Louro1,2, A. Quinot2, E. Neto3, J. E. Fernandes3, D. Marian4, M. Vecchiati4, P. Caciagli4 and A.M. Vaira4*

1 Estação Agronómica Nacional, INIAP, Quinta do Marquês, 2784-505 Oeiras, Portugal
2 Direcção-Geral de Protecção das Culturas, Quinta do Marquês, 2780-515 Oeiras, Portugal
3 Direcção Regional de Agricultura do Algarve, Apart. 282, 8001-904 Faro, Portugal
4 Istituto di Virologia Vegetale, CNR, Strada delle Cacce 73, 10135 Torino, Italy

*a.vaira@ivv.cnr.it

Accepted for publication 15/12/03

Cucumber vein yellowing virus (CVYV), a tentative member of the genus Ipomovirus (Family Potyviridae) (Lecoq et al., 2000), has caused severe diseases in cucurbits in the East Mediterranean Basin for over four decades (Cohen & Nitzany, 1960). Recently, it was detected in Spain both in cultivated cucurbits and weeds (Cuadrado et al., 2001; Janssen et al., 2002).

Figure 1: CVYV symptoms on cucurbits. Left - typical vein clearing symptoms on a leaf of field grown cucumber;
right - fruit necrosis in a split fruit of watermelon.

During the summer of 2002 in Algarve (southern Portugal), vein yellowing, stunting and sudden plant death were observed in protected melons (Cucumis melo), heavily infested by Bemisia tabaci. Watermelons (Citrullus lanatus), grown nearby, showed mild leaf chlorosis and split fruits with internal necrosis; cucumbers (Cucumis sativus) and squashes (Cucurbita pepo) showed vein clearing and mottling on leaves. Fifteen of 52 field samples, belonging to the four species, were shown to be infected with CVYV when tested by RT-PCR with specific primers (Cuadrado et al., 2001) by a one-step procedure. Most samples were also infected with Cucurbit yellow stunting disorder virus (CYSDV), another whitefly-borne virus endemic in the region, but free from other viruses commonly infecting cucurbits. One CVYV isolate from cucumber was experimentally transmitted to zucchini (Cucurbita pepo) by B. tabaci in the semi-persistent manner. From field samples, CVYV was mechanically transmitted to known host species of the virus. All transmissions were confirmed by RT-PCR. Four amplified fragments, one from each species, were sequenced, showing 100% identity with each other and the 449 bp sequence of a CVYV isolate from cucumber was submitted to GenBank (AY424869). The sequence showed 99% identity with the isolate AM48 from Spain (AY290865) and 96% with an isolate from Israel (AF233429). Surveys during the summer of 2003 confirmed the presence of CVYV in cucurbits in the same area. The actual impact of CVYV in the local pathosystem cucurbits/whitefly-borne viruses has yet to be determined. This is the first report of the occurrence of CVYV in Portugal.

Acknowledgments

This work was conducted in the framework of a scientific Bilateral Agreement between ICCTI (Portugal) and CNR (Italy).

References

Cohen S, Nitzany FE, 1960. A whitefly-transmitted virus of cucurbits in Israel. Phytopathologia Mediterranea 1, 44-46.

Cuadrado IM, Janssen D, Velasco L, Ruiz L, Segundo E, 2001. First report of Cucumber vein yellowing virus in Spain. Plant Disease 85, 336.

Janssen D, Ruiz L, Velasco L, Segundo E, Cuadrado IM, 2002. Non-cucurbitaceous weed species shown to be natural hosts of Cucumber vein yellowing virus in south-eastern Spain. New Disease Reports [http://www.bspp.org.uk/ndr/] Volume 5.

Lecoq H, Desbiez C, Delécolle B, Cohen S, Mansour A, 2000. Cytological and molecular evidence that the whitefly-transmitted Cucumber vein yellowing virus is a tentative member of the family Potyviridae. Journal of General Virology 81, 2289-2293.

The British Society for Plant Pathology