Molecular characterisation of a cloned DNA from a tomato yellow leaf curl virus isolate form Sicily

A DNA molecule, 2773 nucleotides long, was isolated from tomato plants infected by tomato yellow leaf curl bigeminivirus in Sicily, Italy (TYLCV-Sc). The DNA was cloned and sequenced. Comparisons with other TYLCV isolates from Sardinia and Spain (western Mediterranean region) showed high total sequence homology (>90%), with lower homology levels (80-84%) in the intergenic regions. Total DNA homology dropped to 76% when TYLCV-Sc was compared with an isolate from Israel (TYLCV-Is). The lower homology was confirmed by the use of digoxigenin-labelled probes prepared from TYLCV-Sc and TYLCV-Is. In dot blot experiments on samples collected in different Mediterranean areas, the TYLCV-Sc probe reacted strongly with western Mediterranean isolates and moderately with those from eastern Mediterranean zones. When cloned TYLCV-Sc DNA were replicated in tobacco protoplasts, no differences were observed in viral DNA forms, compared with DNA of TYLCV-Sr (a Sardinian isolate).