January 20, 2003
From: British Society of Plant Pathology, New Disease Reports, vol 8 [edited]

Occurrence of Cucumber vein yellowing virus in cucurbitaceous species in southern Portugal
D. Louro [1] (Estacao Agronomica Nacional, INIAP, Quinta do Marques, 2784-505 Oeiras, Portugal; A. Quinot (as for Louro [2]); E. Neto (Direccao Regional de Agricultura do Algarve, Apart. 282, 8001-904 Faro, Portugal); J. E. Fernandes (as for Neto); D. Marian (Istituto di Virologia Vegetale, CNR, Strada delle Cacce 73, 10135 Torino, Italy); M. Vecchiati (as for Marian); P. Caciagli (as for Marian); A.M. Vaira <a.vaira@ivv.cnr.it>. Accepted for publication 15 Dec 2003.

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 4 decades (Cohen & Nitzany, 1960). Recently, it was detected in Spain both in cultivated cucurbits and weeds (Cuadrado et al., 2001; Janssen et al., 2002).

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.

15 of 52 field samples, belonging to the 4 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 were 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.

4 amplified fragments, one from each species, were sequenced, showing 100 percent identity with each other, and the 449-bp sequence of a CVYV isolate from cucumber was submitted to GenBank (AY424869). The sequence showed 99 percent identity with the isolate AM48 from Spain (AY290865) and 96 percent 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.

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, Delecolle 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.

[CVYV, first reported from Israel in 1960, has subsequently spread within the EPPO region (Israel, Jordan, Portugal, Spain, Turkey) and Sudan. The disease affects cucumber, pumpkin, squash, and watermelon. CVYV wreaks havoc on cucurbit hosts in the eastern Mediterranean region, causing considerable crop loss. Information on disease management is meager. Attempts to reduce losses center on use of virus-free seedlings, provision of screens in glasshouse production systems to prevent viruliferous whiteflies (_B. tabaci_) from feeding on plants, use of chemical insecticides, implementing a period of at least a month between seeding new crops, and biological control using predacious insects (_Encarsia formosa_), a parasitic wasp, and the beetle _Delphasutus pusillus_. The fact that cucumber vein yellowing disease is present across the southern flank of Europe is of concern to plant pathologists and entomologists. - Mod.DH]