The nucleotide sequence of an infectious clone of the geminivirus beet curly top virus

Abstract

A number of infectious clones of a Californian isolate of the leafhopper-transmitted geminivirus beet curly top virus (BCTV) have been constructed from virus-specific double-stranded DNA isolated from infected Beta vulgaris and used to demonstrate a single component genome. The nucleotide sequence of one infectious clone has been determined (2993 nucleotides). Comparison with other geminiviruses has shown that the organisation of the genome closely resembles DNA 1 of the whitefly-transmitted members. The four conserved coding regions of DNA 1 have highly homologous counterparts in BCTV with the exception of the putative coat protein which is more closely related to those of the leafhopper-transmitted geminiviruses suggesting a strong interrelationship between coat protein and insect vector. A BCTV component equivalent to DNA 2 is not required for virus infection or transmission and has not been isolated from infected plants.