Mutagenesis of the virion-sense open reading frames of tomato leaf curl geminivirus.

A series of frame shift, deletion, and inversion mutants in the virion-sense open reading frames (ORFs) of the monopartite geminivirus tomato leaf curl virus have been constructed and their ability to replicate, produce single-stranded DNA, spread, and cause symptoms in tomato plants has been investigated. Disruptions in the V1 ORF lead to symptomless, systemic infections with a reduced titer of all viral DNA forms while interruptions in the V2 (coat protein) ORF disrupted spread of the virus. Mutagenesis of the virion-sense ORFs did not affect the replication of viral double-stranded DNA, although both V1 and V2 products appear to play a role in the accumulation of viral single-stranded DNA.