Cucumber vein yellowing virus (CVYV) is transmitted by Bemisia tabaci, it has a narrow host range restricted to some cucurbitaceous plants including Cucumis sativus, C. melo, C. melo var. flexousus, Cucurbita pepo, C. foesti, Citrullus vulgaris, C. colocynthis and Lagenaria siceraria.Although a single whitefly can transmit the disease, the efficiency of transmission was low. At least 15-20 insects per plant were required to cause an infection of 55 % of inoculated plants. The minimum acquisition and inoculation feeding periods were 30 and 15 min, respectively.The latent period in the vector is about 75 min and the whitefly was infectious for not more than 5h. ZusammenfassungCucumber vein yellowing virus; Wirtsspektrum und Virus-Vektor-Wechselwirkungen Cucumber vein yellowing virus (CVYV) wird durch Bemisia tabaci ubertragen. Das Wirtsspektrum ist eng und besehrankt sich auf einige Kiirbisgewachse wie Cucumis sativus, C. melo, C. melo vzr. flexousus, Cucurbita pepo, C. foesti, Citrullus vulgaris, C. colocynthis und Lagenaria siceraria. Obwohl eine einzige Wei£e Fliege die Krankheit iibertragen kann, ist die Ubertragungseffizienz niedrig. Um eine Infektion bei 55 % der inokuherten Pflanzen zu erzielen, waren mindestens 15-20 Insekten pro Pflanze notwendig. Die minimalen Erwerbs-und Inokulationsfiitterungsperioden betrugen 30 bzw. 15 min. Die Latentperiode im Vektor betragt ca. 75 min und die Weifie Fhege bleibt bis zu 5 h infektios.

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glutinosa and A', tabacum evs Samsun and Havana 423 were infected without showing s.'The whitefly Betnista tahaci is an efficient veetor; a single whitefly was able to transmit the virus veetor relationships of the Jordanian isolate are reported for the first time.

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The incidence of watermelon chlorotic stunt disease and the molecular characterization of the Jordanian isolate of Watermelon chlorotic stunt virus (WmCSV-[JO]) are described in this study. Symptomatic leaf samples obtained from watermelon (Citrullus lanatus Thunb.), melon (Cucumis melo L.), squash (Cucurbita pepo), cucumber (Cucumis sativus L.), and bottle gourd (Lagenaria siceraria) plants were tested for WmCSV-[JO] infection by PCR. The virus could be detected in 8 melon and 87 watermelon samples obtained from Ghor Assafi (southern part of Jordan Valley). Three samples collected from Mafraq (eastern part of Jordan) were found mixed infected with WmCSV-[JO] and Squash leaf curl virus. The full-length DNA-A and DNA-B genomes of WmCSV-[JO] were amplified, and sequences were deposited in the GenBank under accession numbers EU561237 and EU561236, respectively. Sequence analysis reveals that WmCSV-[JO] is closely related to other virus isolates from Israel (WmCSV-[IL]), Yemen (WmCSV-[YE]), Iran (WmCSV-[IR]), Lebanon (WmCSV-[LB]), and Sudan (WmCSV-[SD]). DNA-A of WmCSV-[JO] showed highest nucleotide identity (99.42%) with WmCSV-[IL], while DNA-B had highest nucleotide identity (95.52%) with WmCSV-[YE]. Data of this study demonstrate that digestion of DNA-B genome of WmCSV isolates with ApaI enzyme can discriminate between these isolates at the molecular level. Infectious clones of WmCSV-[JO] were constructed and agroinoculated to Nicotiana benthamiana plants. Inoculated plants developed mild disease symptoms 4 weeks post inoculation, while watermelon plants biolistically inoculated with WmCSV-[JO] developed characteristic mottling, yellowing and severe leaf curling symptoms 3 weeks post inoculation.