| Summary: | Two whitefly transmitted cotton geminiviruses that differ in symptoms, but have similar ecological properties, were characterized and compared at the molecular level. The viruses, cotton leaf crumple (CLCrV) and cotton leaf curl (CLCuV) are found opposite sides of the world, CLCrV in the western hemisphere, including southwestern US, Mexico and Central America and CLCuV in Pakistan, other Asian countries and Africa. During recent years leaf curl has been a catastrophic disease being responsible for converting Pakistan to net importer rather than exporter of cotton. DNA A component of each virus was cloned with a polymerase chain reaction-based technique. The complete sequence of CLCrV and CLCuV DNA A were determined to be 2630 and 2725 nucleotides, respectively. Sequence analysis show that CLCrV and CLCuV CLCrV were most related to geminiviruses found in that part of the world from which they originated. Thus CLCrV was most closely related to 'New World' viruses such as bean dwarf mosaic and squash leaf curl viruses, while CLCuV was most closely related to 'Old World' viruses such as Indian cassava mosaic and tomato yellow leaf curl. CLCrV and CLCuV are least related to each other among the whitefly-transmitted geminiviruses. Genome organizations predicted from the nucleic acid sequences and phylogenetic analysis of whitefly-transmitted geminiviruses also reflect these relationship.
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