HIGH EXPRESSION OF TRUNCATED VIRAL REP PROTEIN CONFERS RESISTANCE TO TOMATO YELLOW LEAF CURL VIRUS IN TRANSGENIC TOMATO PLANTS

A truncated version of the Cl gene of tomato yellow leaf curl geminivi rus (TYLCV), encoding the first 210 amino acids of the multifunctional Rep protein, was introduced by Agrobacterium transformation into Lyco persicon esculentum cv. Moneymaker plants under the transcriptional co ntrol of an enhanced cauliflower mosaic virus 35S promoter. One R-0 pl ant (line 47) carrying the Cl gene in two loci (A and B) and accumulat ing the truncated Rep protein (T-Rep), was crossed with either a wild- type plant, or a CI antisense plant (line 10). The wild type (wt) x 47 progeny were phenotypically homogeneous, contained either A or B locu s, expressed high levels of T-Rep protein, had a ''curled'' phenotype, and were resistant to TYLCV when challenged either by agroinfection o r by the vector Bemisia tabaci. In the 10 x 47 progeny, plants carryin g only the sense gene behaved like the wt x 47 progeny, while those co ntaining both sense and antisense transgenes did not accumulate the T- Rep protein, showed a normal phenotype, and were not resistant, showin g that accumulation of T-Rep protein is required to confer TYLCV resis tance. Plants accumulating T-Rep were susceptible to a distinct gemini virus, tomato leaf curl virus (ToLCV-Au).