Viral dynamics: notes from plant-infecting ssDNA viruses
Over the past five years an overwhelming diversity of plant–infecting circular single stranded DNA viruses (ssDNA) has been catalogued. This has primarily been attributed to new molecular tools for non-specifically amplification of circular DNA coupled with cheap sequencing. The high resolution of data, for example for mastreviruses and begomoviruses, has enabled our team to address important aspects of viral evolution and spread using Bayesian phylogeographic analysis to reconstruct the plausible history and diversification of these viruses at a continental and global scale. For example, 1) Maize streak virus strain-A (MSV-A) which seems to have emerged in Southern Africa in the 1860s though recombination of mastreviruses infecting indigenous grasses (MSV-B and ancestral MSV-F/G-likes) an, has spread transcontinentally at an average rate of 32.5 km/year, 2) Tomato yellow leaf curl virus (TYLCV) a pathogen crippling tomato production globally most probably arouse in the Middle East between 1930s and 1950s, with a global spread occurring in the 1980s and recombination playing a major role in its evolution. One of the more striking discoverers, from our evolution experiments and also analysis of sequences available in public databases by others, is that plant-infecting ssDNA viruses are evolving at rates (between 2 and 3 x 10-4 substitutions/site/year) similar to those of RNA viruses. Our recombination experiments on mastreviruses reveal that these viruses are extremely efficient at exploring fitness landscapes, the mechanistic predispositions of different genomic regions to recombination can strongly influence the accessibility of high-fitness recombinants and the frequency with which these genomes arise correlates directly with the escalating selection pressures imposed by increasingly resistant host varieties. To add to the evolutionary complexity of ssDNA viruses, we have found multi-component nanoviruses, primarily Banana bunchy top virus (BBTV), to be evolving through, not only genetic drift, but also through a degree of intra- and inter component recombination and reassortment. In summary, plantinfecting ssDNA viruses are highly capable of exploring sequences space efficiently.
| Main Authors: | , , , , , , , , , , , |
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| Format: | conference_item biblioteca |
| Language: | eng |
| Published: |
IITA
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| Subjects: | H20 - Maladies des plantes, U30 - Méthodes de recherche, |
| Online Access: | http://agritrop.cirad.fr/581453/ http://agritrop.cirad.fr/581453/3/Page%2085%20de%20IPVE%20-%2012th%20-%202013-01-28_2013-02-01-%20BOOK%20OF%20ABSTRACTS.pdf |
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| Summary: | Over the past five years an overwhelming diversity of plant–infecting circular single stranded DNA viruses (ssDNA) has been catalogued. This has primarily been attributed to new molecular tools for non-specifically amplification of circular DNA coupled with cheap sequencing. The high resolution of data, for example for mastreviruses and begomoviruses, has enabled our team to address important aspects of viral evolution and spread using Bayesian phylogeographic analysis to reconstruct the plausible history and diversification of these viruses at a continental and global scale. For example, 1) Maize streak virus strain-A (MSV-A) which seems to have emerged in Southern Africa in the 1860s though recombination of mastreviruses infecting indigenous grasses (MSV-B and ancestral MSV-F/G-likes) an, has spread transcontinentally at an average rate of 32.5 km/year, 2) Tomato yellow leaf curl virus (TYLCV) a pathogen crippling tomato production globally most probably arouse in the Middle East between 1930s and 1950s, with a global spread occurring in the 1980s and recombination playing a major role in its evolution. One of the more striking discoverers, from our evolution experiments and also analysis of sequences available in public databases by others, is that plant-infecting ssDNA viruses are evolving at rates (between 2 and 3 x 10-4 substitutions/site/year) similar to those of RNA viruses. Our recombination experiments on mastreviruses reveal that these viruses are extremely efficient at exploring fitness landscapes, the mechanistic predispositions of different genomic regions to recombination can strongly influence the accessibility of high-fitness recombinants and the frequency with which these genomes arise correlates directly with the escalating selection pressures imposed by increasingly resistant host varieties. To add to the evolutionary complexity of ssDNA viruses, we have found multi-component nanoviruses, primarily Banana bunchy top virus (BBTV), to be evolving through, not only genetic drift, but also through a degree of intra- and inter component recombination and reassortment. In summary, plantinfecting ssDNA viruses are highly capable of exploring sequences space efficiently. |
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