Infection of Nicotiana benthamiana with Uncut Cloned Tandem Dimers of Tomato Golden Mosaic Virus DNA

Department of Pure and Applied Biology, Imperial College of Science and Technology, Prince Consort Road, London SW7 2BB, U.K. Recombinant plasmids containing dimeric inserts of tomato golden mosaic virus (TGMV) DNA component A (pA2), DNA component B (pB2) and both DNA components (pA2B2) were constructed. When inoculated onto Nicotiana benthamiana plants, mixtures of uncut pA2 and pB2, or uncut pA2B2 alone, induced symptoms typical of TGMV infection. Infections induced by the uncut dimeric clones were very similar to those induced by the excised monomeric clones, as judged by symptom development, production of capsid protein, immunological reaction with antiserum to TGMV, production of circular double-stranded DNA and single-stranded DNA of genome size, and restriction analysis of supercoiled DNA. Infection with the dimeric DNA clones gave rise to a subgenomic DNA, derived from DNA A, which was not observed in infections with monomeric clones. The infectivity of excised monomeric DNA was shown to be dependent on the cloning site, but the uncut dimeric clones were as infectious as the most infectious monomeric clones. Keywords: TGMV, uncut cloned dimers, geminivirus Present address: Department of Eukaryotic Molecular Genetics, National Institute for Medical Research, Mill Hill, London NW7 1AA, U.K. Received 19 August 1987; accepted 29 September 1987.