Geminiviruses - As with the Ti plasmid Agrobacterium and cauliflower mosaic virus, the potential of geminiviruses as gene-cloning vectors for plants, stems from the work on several plant diseases now recognized as being caused by these agents.

Both curly top virus (CTV) and maize streak disease virus (MSV) are geminiviruses characterized on the basis of their unique virion morphology and possession of single stranded DNA. Geminiviruses have a much wider host range than CaMV

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