UMR Biologie et Génétique des Interactions Plante-Parasite
jeudi 26 janvier 2017
Grande salle de réunion de BGPI – 11h
Bât. K | Campus CIRAD-Baillarguet | Montpellier
Experimental evolution of genome organization
in a plant RNA virus
Anouk Willemsen
IRD, MIVEGEC, post-doc
The evolution of genome architecture – the dimensions and organization of an organism’s hereditary material – is poorly understood. There are clear differences in genome architecture over organisms, and it is clear that this complexity can be altered on relatively short time scales. Here, three specific processes of the evolution of genome architecture in viruses are studied: (i) the reshuffling of existing elements, (ii) the decrease of genome complexity through loss of redundant or unnecessary genetic material, (iii) and the increase of genome complexity through the acquisition of new genes. These topics were addressed in vivo using Tobacco etch virus, a plant RNA virus, as a model organism. Important changes in the viral genome were generated – from changes in gene order, to duplications of existing genes, to the introduction of exogenous sequences – followed by experimental evolution to observe how these changes were accommodated. The evolved and ancestral lineages were compared by next-generation sequencing and measurements of virulence, viral accumulation and within-host competitive fitness. First, we identified multiple barriers to the evolution of alternative gene orders. Second, we observed differences in the deletion dynamics of genetically and functionally redundant sequences and we developed a model to predict the stability of gene insertions. Third, we found an exogenous sequence that was evolutionary stable in the Tobacco etch virus genome that does not appear to affect viral fitness and can act as a backup in case of failure of the viral host defense mechanism. Lastly, we observed that a host species jump can be a game changer for evolutionary dynamics, allowing unstable viruses to be competitive in alternative hosts.
Recent publications:
- Willemsen, A., Zwart, M. P., Higueras, P., Sardany_es, J., and Elena, S. F. (2016) Predicting the Stability of Homologous Gene Duplications in a Plant RNA Virus. Genome Biology and Evolution 8(9):3065-3082.
- Willemsen, A., Zwart, M. P., Tromas, N., Majer, E., Daròs, J.-A., and Elena, S. F. (2016) Multiple barriers to the evolution of alternative gene orders in a positive-strand RNA virus. Genetics 202(4):1503-1521.
- Velasco, L., Salem, N., Willemsen, A., Lapidot, M., Mansour, A. N., Rubio, L., and Galipienso, L. (2016) Genetic variation and evolutionary forces shaping Cucumber vein yellowing virus populations: risk of emergence of virulent isolates in Europe. Plant Pathology 65(5):847-856.
Contact: Edwige Berthelot ;