Identification and characterization of a mechanical transmissible begomovirus causing leaf curl on oriental melon

Abstract

Oriental melon plants, Cucumis melo var. makuwa cv. Silver Light, showing virus-induced symptoms of mosaic, leaf curl and puckering were observed in the fields of eastern Taiwan in 2007. A virus culture, designated as SL-1, isolated from the diseased melon was established in systemic host plants, Nicotiana benthamiana and oriental melon, by mechanical inoculation. SL-1 did not react to the antisera against common cucurbit-infecting RNA viruses. Viral DNAs extracted from the diseased plant were amplified with the degenerate primers for begomoviruses. The full-length genomic DNA-A and DNA-B of SL-1 were sequenced and found to be closest, with 97.7% and 90.6% nucleotide identity, respectively, to Tomato leaf curl New Delhi begomovirus (ToLCNDV) cucumber isolate from a group of cucurbit-infecting begomoviruses. The virus SL-1 was designated as ToLCNDV oriental melon isolate (ToLCNDV-OM). The pathogenicity of ToLCNDV-OM was confirmed by agroinfection. Progeny virus from the agroinfected N. benthamiana plants was able to infect oriental melon by mechanical inoculation and caused symptoms similar to the original diseased melon in the field. The ToLCNDV-OM also infected five other species of cucurbitaceous plants by mechanical inoculation. This is the first report of a new ToLCNDV isolate causing severe disease on oriental melon in Taiwan

Mechanical transmission of Tomato leaf curl New Delhi virus to cucurbit germplasm: selection of tolerance sources in Cucumis melo

“…It has been speculated that differences between isolates in the length of the nuclear shuttle protein (NSP) may account for these differences. Mechanically transmissible isolates had shorter NSPs because of the loss of amino-acids in the N terminus, which has been shown to be decisive in symptom development and as a virulence determinant (Chang et al 2010).…”

“…Chang et al (2010) reported the mechanical transmission of a ToLCNDV isolate from Taiwan (ToLCNDV-OM) found in oriental melons (Cucumis melo var. makuwa, variety included in the group conomon of the subspecies agrestis) to the original host, to other accessions of the conomon group, and to four other cucurbits: bottle gourd, cucumber, zucchini squash, and sponge gourd.…”

“…ex Schrad. and Cucurbita moschata Duchesne (Chang et al 2010). In contrast, another isolate from the same area could not be mechanically transmitted to cucumber (Samretwanich et al 2000).…”

“…), pumpkin (Cucurbita maxima Duchesne), chilli pepper (Capsicum spp.) and potato (Solanum tuberosum L.) (Chang et al 2010;Khan et al 2012;Jyothsna et al 2013;Bandaranayake et al 2014).…”

“…Although most ToLCNDV isolates are only naturally transmitted by the whitefly Bemisia tabaci (Gennadius) in a persistent manner (Chang et al 2010), some of them have been shown to be mechanically sap transmitted to their original hosts. A strain of ToLCNDV causing yellow mosaic and leaf distortion symptoms in potato in India was sap transmitted to Nicotiana benthamiana Domin and potato plants (Usharani et al 2004).…”