Abstract
During 1992 and 1993 growing seasons, 385 curcubit plant samples showing virus like symptoms have been collected for the purpose of identifying nine viruses that might cause cucurbit diseases in Riyadh, Gassim and Hail regions. The direct or indirect ELISA and agar double diffusion tests have been used for the identification. All the nine plant viruses to which the tests were performed have been identified in the central area of Saudi Arabia (Riyadh, Gassim and Hail regions). The zucchini yellow mosaic virus (ZYMV) was identified from all cultivated cucurbit species: cucumber (Cucumis sativus L.), melon (Cucumis melo L.), watermelon (Citrullus lanatus Thunb.), pumpkin (Cucurbita maxima Duch.), squash (Cucurbita pepo L.), bottlegourd (Lagenaria siceraria L.) and snake cucumber (Cucumis melo var flexuoses). The squash mosaic virus (CMV), watermelon mosaic virus-1 (WMV-1) which is known as papaya ringspot virus (PRSV) were identified from all previously mentioned cucurbit species except from bottlegourd, pumpkin and snake cucumber respectively. The watermelon mosaic virus-2 (WMV-2) was identified from all species except pumpkin and snake cucumber. The Prune dwarf virus (PDV) has been identified from cucumber, melon, squash, and pumpkin. The cucumber green mottle mosaic virus (CGMMV) was identified from watermelon, melon, and bottlegourd. The cucumber leaf spot virus (CLSV) was identified from the plants of squash, pumpkin and bottlegourd, while the beet western yellows virus (BtWYV) was identified from the bottlegourd plants only.
The results of this study confirmed that the ZYMV was the most detected virus affecting all the cucurbit species in the different locations of the central area of Saud Arabia, with 60.5% of detection. The lowest detection percentage (0.5%) was observed with BtWYV. The immunological tests revealed that most of the tested samples had mixed infections, also it revealed that about 25.7% of these samples gave negative reactions to all of the tested viruses.
This is the first complete and comprehensive study on viruses that infect cucurbits in Riyadh, Gassim and Hail regions which together form the central area of Saudi Arabia. In this study, the WMV-1 was identified in the central area for the first time, while four cucurbit viruses which include BtWYV, CLSV, PDV and WMV-2 were identified for the first time not only in the central area alone, but in Saudi Arabia as a whole.