DIFFERENTIATION OF 3 WHITEFLY-TRANSMITTED GEMINIVIRUSES FROM THE-REPUBLIC-OF-YEMEN

Three viruses collected in southern Yemen in 1990, infecting watermelo n, tobacco and tomato were shown to be transmitted by the whitefly Bem isia tabaci and to have particle morphologies typical of geminiviruses . Colonies of B. tabaci collected from different locations and from di fferent hosts were used in virus transmission tests with the same host range of plants. Colonies established from both watermelon and cotton in the Yemen were identified as the squash silverleaf-inducing 'B' bi otype. The culture host of the colony did not influence virus acquisit ion and transmission efficiencies to and from other hosts. The tobacco and tomato geminiviruses had a similar host range, but differed in th eir severity in some hosts. Both these viruses differed from the water melon geminivirus in host range and symptoms. Datura stramonium, an al ternative host for all three viruses, could be co-infected by the wate rmelon and tobacco viruses. B. tabaci was able to acquire both viruses from the co-infected D. stramonium and infect seedlings of either ori ginal host plant species with their respective viruses or D. stramoniu m with both. The viruses were identified as watermelon chlorotic stunt virus, tobacco leaf curl virus and tomato yellow leaf curl virus and were distinguished by cross hybridisation.