Molecular studies on tomato yellow leaf curl geminivirus isolates from the Mediterranean region
So far, four tomato yellow leaf curl geminivirus (EPPO A2 quarantine pest) isolates from the Mediterranean region have been sequenced (2 from Israel, 1 from Italy (Sardinia), 1 from Spain). Studies have been carried out in Italy on a TYLCV isolate from Sicily, where the disease has been reported to reduce the tomato production since 1988. The DNA of this isolate has been cloned and sequenced. Comparisons with other isolates from western Mediterranean region (Sardinia and Spain) showed high total sequence homology (above 90;%), whereas with the isolate from the eastern Mediterranean region (Israel) a lower homology was obtained (76 %). These results were also confirmed by the use of digoxigenin-labelled probes prepared from the TYLCV isolates from Sicily and from Israel. In dot-blot experiments on samples prepared from TYLCV-infected tomatoes and collected in different Mediterranean areas (Sicily, Sardinia, Lebanon and Turkey), the TYLCV-Sicily probe reacted strongly with western Mediterranean isolates and moderately with those from the eastern Mediterranean. The authors noted that, in the Mediterranean Basin, it would be preferable to use a mixture of probes, in order to detect both western and eastern isolates. They concluded that these results confirmed that the isolate from Sicily belongs to the west Mediterranean group and they considered that it is unlikely that tomato yellow leaf curl disease reached western Europe through the Middle East (where it is indigenous). Therefore, further epidemiological studies will be necessary to identify the origin of TYLCV in the West Mediterranean Basin.
Sources
Crespi, S.; Noris, E.; Vaira, A.M.; Accotto, G.P. (1995) Molecular characterization of cloned DNA from a tomato yellow leaf curl virus isolate from Sicily.
Phytopathologia Mediterranea, 34 (2), 93-99.