RECOMBINATION BETWEEN VIRAL-DNA AND THE TRANSGENIC COAT PROTEIN GENE OF AFRICAN CASSAVA MOSAIC GEMINIVIRUS

Nicotiana benthamiana was transformed with three different constructs (pCRA1, pCRA2 and pJC1) containing the coat protein coding sequence of African cassava mosaic virus (ACMV). Transformed plants were inoculat ed with a coat protein deletion mutant of ACMV that induces mild syste mic symptoms in control plants. Several inoculated plants of transgeni c lines CRA1/3, CRA1/4, CRA2/1 and CRA2/2 developed severe systemic sy mptoms typical of ACMV, DNA analysis revealed that, in these plants, r ecombination had occurred between the mutant viral DNA and the integra ted construct DNA, resulting in the production of recombinant virus pr ogeny with 'wild-type' characteristics. No reversion of mutant to 'wil d-type' virus was observed in pJC1-transformed plants. Recombinant vir us from several transgenic plants was analysed by PCR and parts of DNA A of virus progeny were cloned. Sequence analysis revealed that only a few nucleotides were changed from the published sequence.