Pseudorecombination and complementation between potato yellow mosaic geminivirus and tomato golden mosaic geminivirus

Abstract

Pseudorecombinants made by exchanging the cloned, infectious genome components (DNAs A and B) of potato yellow mosaic geminivirus (PYMV) and the common strain (cs) of tomato golden mosaic geminivirus (csTGMV) are not infectious in their common host Nicotiana benthamiana. In an N. benthamiana leaf disc assay neither PYMV DNA A nor TGMV DNA A trans-replicated each other's DNA B component. The ability of TGMV to mediate the systemic movement of each other's DNA A was investigated following co-inoculation of N. benthamiana with both genome components of one virus (the helper virus) and DNA A of the other virus (the dependent virus). Movement of the dependent virus DNA A in both cases illustrates interchangeability between the DNA B-encoded movement proteins of New World geminiviruses which infect solanaceous hosts. We have studied this genetic interchangeability further in separate co-agroinoculation experiments with N. benthamiana plants using TGMV DNA A to complement mutations in PYMV open reading frame (ORF) AC2, which encodes a protein that trans-activates the expression of virion sense promoters, and in PYMV ORF AC3, which specfies a protein that enhances viral DNA replication. TGMV DNA A complemented a PYMV AC2 mutant and restored its infectivity and it also complemented a PYMV AC3 mutant and restored the reduced DNA phenotype

Recombination in Eukaryotic Single Stranded DNA Viruses

“…An important criterion that must be met for genome reassortants to be fully functional, however, is that their reassorted components and the genes they encode must interact efficiently with one another [96,110]. For example, the Rep and movement proteins expressed by a reassortant (Figure 1) must respectively trans-replicate and move all of its genome components.…”

Multitasking in Replication Is Common among Geminiviruses

“…Several factors have promoted the epidemics: transportation of plant material, increase and diversification of insect vector populations, and recombination between geminiviruses that coinfect host plants. Geminiviruses may contain monopartite or bipartite genomes (45), and consequently recombination may occur in two different ways: by exchange of viral chromosomes (interchromosomal recombination, or "pseudorecombination" as plant virologists call this type of reassortment) (54,55,61,62) or by crossover of chromosomes (intrachromosomal recombination) (5,6,17,19,38,46,68,69). Moreover, geminiviruses are able to adopt satellite-like DNA circles which have an additional impact on pathogenesis (7,12,47).…”

Analysis of watermelon chlorotic stunt virus and tomato leaf curl Palampur virus mixed and pseudo-recombination infections

“…Pseudo-recombinants can be produced between bipartite geminiviruses under experimental conditions by reassortment of the genomic components of closely related begomovirus strains [9,10,17,29,35,36,41,43] or distinct begomovirus species [2,12,19,31,45]. Homology sequence dependency in pseudo-recombination is due to the compatible interaction between the replication-associated protein (Rep) with the Rep-specific cis elements within the Virus Genes common region of bipartite begomoviruses genome.…”