Yang, G., S. Tolkowsky Laboratory, Department of Virology, Volcani Center, Bet Dagan 50250, Israel
Mawassi, M., S. Tolkowsky Laboratory, Department of Virology, Volcani Center, Bet Dagan 50250, Israel
Ashoulin, L., S. Tolkowsky Laboratory, Department of Virology, Volcani Center, Bet Dagan 50250, Israel
Gafny, R., S. Tolkowsky Laboratory, Department of Virology, Volcani Center, Bet Dagan 50250, Israel
Gaba, V., S. Tolkowsky Laboratory, Department of Virology, Volcani Center, Bet Dagan 50250, Israel
Gal-On, A., S. Tolkowsky Laboratory, Department of Virology, Volcani Center, Bet Dagan 50250, Israel
Bar-Joseph, M., S. Tolkowsky Laboratory, Department of Virology, Volcani Center, Bet Dagan 50250, Israel

A naturally occurring defective RNA of 2379 nt (D2.3) from the VT strain of citrus tristeza closterovirus (CTV) was cloned and sequenced. The D2.3 RNA is a fusion of two regions of 1521 and 858 nt from the 5' and 3' ends of the CTV genome, respectively. A cDNA clone of D2.3 RNA was tagged by the insertion of a 0.47 kb chimeric DNA fragment and the recombinant cDNA was inserted downstream of the cauliflower mosaic virus 35S promoter. The resulting construct was bombarded into CTV-infected tissue, which was then grafted onto virus-free plants. The presence of recombinant RNA in systemically infected leaves was demonstrated by RT-PCR. Sequencing the RT-PCR products synthesized from double-stranded RNA confirmed the presence of the chimeric segment used for tagging. This is the first report of an infectious cDNA molecule derived from CTV D-RNA.