Annu. Rev. Phytopathol. 1994. 32:337-62

RNA-RNA RECOMBINATION AND EVOLUTION IN VIRUS-INFECTED PLANTS

A. E. Simon* and J. J. Bujarski#

*Department of Biochemistry and Molecular Biology and Program in Molecular and Cellular Biology, University of Massachusetts, Amherst, Massachusetts 01003-4505

#Department of Biological Sciences and Plant Molecular Biology Center, Northern Illinois University, DeKalb, Illinois 60115-2861

Viruses that depend on RNA-dependent RNA polymerases (RdRp) for replication of their genomic and subgenomic RNAs are subject to high inherent misincorporation of nucleotides that can lead to heterogeneous mixtures of related species. It has been proposed that RNA viruses evolved the means for correcting high error rates through an ability to recombine mutant genomes with wild-type genomes, thereby maintaining functional integrity. Although originally found only in a select number of animal viruses, RNA recombination is now thought to have been a major factor in the evolution of all viruses. This view is based on sequence comparisons that suggest past recombination events, as well as the detection of de novo recombinant molecules. The role of RNA recombination in virus evolution is also supported by studies indicating that recombinant viruses have a selective advantage over parental viruses in certain instances.