Higher plants can be infected by a large number of viruses, most of which have RNA genomes. The family Geminiviridae is one of the only two plant virus families that have DNA genomes and replicate through DNA intermediates. These pathogens are a large and diverse group of angiospcrm viruses that are characterized by twin icosahedral capsids and circular single-stranded DNA (ssDNA) genomes. Each geminate particle encapsidates one ssDNA molecule (2.5 to 3.0 kb) that replicates in the nuclei of the infected cells via a double-stranded DNA (dsDNA) intermediate (Lazarowitz. 1992).