COMPARISON OF A BEET CURLY TOP VIRUS ISOLATE ORIGINATING FROM THE OLD-WORLD WITH THOSE FROM THE NEW-WORLD

The complete nucleotide sequence of an infectious, insect-transmissibl e clone of a beet curly top virus isolate originating from Iran (BCTV- I) has been determined. The nucleotide sequence of BCTV-I shows high l evels of similarity to the sequences of BCTV strains isolated from Nor th America, and is nearly identical to the CFH strain of BCTV. The sym ptoms produced by BCTV-I in Nicotiana benthamiana and Beta vulgaris mo st closely resemble those of the CFH strain and are distinct from the other isolates. The significance of these findings with respect to the possible geographic origins and evolution of BCTV are discussed.