Studies on whitefly-transmitted geminiviruses in Yemen
In Yemen, whitefly-transmitted viruses have caused increasing economic damage to crops. Three viruses collected in southern Yemen in 1990, on watermelon, tobacco and tomato have been studied and were shown to be transmitted by Bemisia tabaci. These viruses were identified as watermelon chlorotic stunt geminivirus, tobacco leaf curl geminivirus and tomato yellow leaf curl geminivirus (EPPO A2 quarantine pest). In addition, colonies of B. tabaci established on watermelon and cotton in Yemen have been found to induce squash silverleaf symptoms and are therefore considered as being the B biotype (B. argentifolii). Analysis of transmission efficiencies of the three viruses showed that tobacco leaf curl geminivirus and tomato yellow leaf curl geminivirus were transmitted more efficiently than watermelon chlorotic stunt geminivirus. The authors have found that the TYLCV isolate from Yemen presented the highest levels of homology with the Spanish isolate and showed also similarities with a Jordanian isolate. They concluded that the Yemen isolate of TYLCV could be provisionally classified within the complex of yellow leaf curl geminiviruses prevalent in the Middle East and Mediterranean region. According to the EPPO Secretariat, this is the first report of tomato yellow leaf curl geminivirus in Yemen.
Sources
Bedford, I.D.; Briddon, R.W.; Jones, P.; Alkaff, N.; Markham, P.G. (1994) Differentiation of three whitefly-transmitted geminiviruses from the Republic of Yemen.
European Journal of Plant Pathology, 100 (3-4), 243-257.