Thesis (M.Sc.) - Cairo University - Faculty of Agriculture - Department of Genetics

Cucurbits are among the major vegetable crops especially in the developing countries. Cucurbits are infected with many diseases, one of the most dangerous casual agent that dramatically affect the yield production is the viral infection. In this research, two of the most important viruses affecting cucurbits, cucurbit yellow stunting disorder virus (CYSDV) and squash leaf curl virus (SLCV), were detected in many governorates in Egypt through a field survey during three successive years (2009, 2010 and 2011). The visual screening was confirmed using RT - PCR and PCR utilizing specific primers for each virus. The two viruses were molecularly and biologically characterized. The SLCV and CYSDV have been isolated and transmitted by using viruliferous whitefly to healthy cucurbits in glass cages under suitable conditions in an insect proof greenhouse. CYSDV and SLCV affect different hosts including a wide range of cucurbitacea family such as cucumber, squash, watermelon and melon as well as non - cucurbits. CYSDV symptoms were appeared on Nicotiana tabacum and chenopodium quinoa, but not appeared or transmitted to phaseolus vulgaris, Abelmoschus esculentus, Solanum lycopersicum or Morus Alba. While, SLCV infected chenopodium quinoa, pepper (capsicum annuum), eggplant (solanum melongena), phaseolus vulgaris and Nicotiana tabacum but did not infect tomato, white mulberry and okra. The CYSDV coat protein gene (CP) of the Egyptian isolate was amplified by RT - PCR then cloned and sequenced

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