Differentiation of three whitefly-transmitted geminiviruses from the Republic of Yemen

Three viruses collected in southern Yemen in 1990, infecting watermelon, tobacco and tomato were shown to be transmitted by the whiteflyBemisia tabaci and to have particle morphologies typical of geminiviruses. Colonies ofB. tabaci collected from different locations and from different 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 biotype. The culture host of the colony did not influence virus acquisition and transmission efficiencies to and from other hosts. The tobacco and tomato geminiviruses had a similar host range, but differed in their severity in some hosts. Both these viruses differed from the watermelon geminivirus in host range and symptoms.Datura stramonium, an alternative host for all three viruses, could be co-infected by the watermelon and tobacco viruses.B. tabaci was able to acquire both viruses from the co-infectedD. stramonium and infect seedlings of either original host plant species with their respective viruses orD. stramonium 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.