The department “Dynamics and Expression of the Genome” employs genetics, cytology, molecular biology and protein biochemistry to investigate the essential mechanisms controlling the structure and function of the genome during meiosis (recombination) and genomic shock (polyploidism), and following biotic and abiotic stresses (control of transposable elements and variations in the epigenetic state of genes implicated in stress responses). Our department also studies the transcriptional (chromatin dynamics and the stability of epigenetic states) and posttranscriptional (processing of endogenous and exogenous aberrant RNAs by RNA Quality Control and RNA silencing pathways) mechanisms controlling gene expression. These studies are carried out in several model plants including the crucifers Arabidopsis thaliana and Brassica napus, the solanaceous species Nicotiana tabacum and Solanum esculentum and basal land plants such as the moss Physcomitrella patens.

Groups

- "Meiosis and Recombination" team studies the key steps of meiosis and meiotic recombination (meiotic cell cycle regulation, initiation of meiotic recombination, double strand break repair pathways, control of the crossing over/non crossover ratio, polyploidization mechanisms, control of recombination in polyploids, and the role of chromatin structure on the distribution of meiotic recombination events). A subset of our group also studies somatic homologous recombination with the aim of developing gene targeting strategies.

- "Transposon-Host Interactions and Plant Biodiversity" team examines the impact of retrotransposons in Solanaceae, from the control of their activities (particularly in response to stress or allopolyploidization) to their molecular evolution, as well as their evolutionary and functional impact. The group also looks at the impact of transcriptional activation of retrotransposons on the expression of cellular genes.

- "Epigenetic natural variation" team studies the role of transcriptional and post-transcriptional epigenetic modifications in the adaptability of plants to environmental stresses. The group is also interested in natural epigenetic variability related to stress responses.

- "Epigenetics" team is investigating the interactions among several RNA Quality Control pathways and RNA silencing, as well as the integration of these pathways during the control of endogenous or exogenous aberrant RNAs (deriving from viruses and transgenes, for example). The group also is interested in small RNA-induced changes in epigenetic chromatin states, the stability of these states and their role in natural variability.

- "Chromatin Dynamics" team studies LHP1 chromatin complexes as well as the mechanisms by which these complexes regulate gene expression. The group also is interested in nuclear architecture and the relationships between structure / function of the genome at the transition between differentiated and dedifferentiated states.

Selected Publications :

d'Erfurth, I., Jolivet, S., Froger, N., Catrice, O., Novatchkova, M., and Mercier, R.(2009). Turning meiosis into mitosis. PLoS Biol, 7 (6) : e1000124. (on-line)

De Muyt, A., Pereira, L., Vezon, D., Chelysheva, L., Gendrot, G., Chambon, A., Lainé-Choinard, S., Pelletier, G., Mercier, R., Nogué, F., and Grelon, M. (2009). A high throughput genetic screen identifies new early meiotic recombination functions in Arabidopsis thaliana. PLoS Genet 5=(9) : e1000654. (on-line)

Mallory, A., Hinze, A., Tucker, M., Bouché, N., Gasciolli, G., Elmayan, T., Lauressergues, D., Jauvion, V., Vaucheret, H., and Laux, T. (2009). Redundant and specific roles of the ARGONAUTE proteins AGO1 and ZLL in development and small RNA-directed gene silencing. PLoS Genet,5 (9) : e1000646. (on-line)

Nicolas, S.D., Leflon, M., Monod, H., Eber, F., Coriton, O., Huteau, V., Chevre, A.M., and Jenczewski, E. (2009). Genetic regulation of meiotic cross-overs between related genomes in Brassica napus haploids and hybrids. Plant Cell, 21 (2): 373-385. (pubmed)

Parisod, C., Salmon, A., Zerjal, T., Tenaillon, M., Grandbastien, M., and Ainouche, M. (2009). Rapid structural and epigenetic reorganization near transposable elements in hybrid and allopolyploid genomes in Spartina. New Phytol, 84 (4):1003-15. (pubmed).

Drouaud, J., Mercier, R., Chelysheva, L., Berard, A., Falque, M., Martin, O., Zanni, V., Brunel, D., and Mezard, C. (2007). Sex-Specific Crossover Distributions and Variations in Interference Level along Arabidopsis thaliana Chromosome 4. PLoS Genet, 3=(6) : e106. (on-line)

Petit, M., Lim, K.Y., Julio, E., Poncet, C., Dorlhac de Borne, F., Kovarik, A., Leitch, A.R., Grandbastien, M.A., and Mhiri, C. (2007). Differential impact of retrotransposon populations on the genome of allotetraploid tobacco (Nicotiana tabacum). Mol Genet Genomics, 278 (1) : 1-15. (pubmed)

Tessadori, F., Chupeau, M.C., Chupeau, Y., Knip, M., Germann, S., van Driel, R., Fransz, P., and Gaudin, V. (2007). Large-scale dissociation and sequential reassembly of pericentric heterochromatin in dedifferentiated Arabidopsis cells. J Cell Sci 120(Pt 7): 1200-1208. (pubmed)

Zhang, X., Germann, S., Blus, B.J., Khorasanizadeh, S., Gaudin, V., and Jacobsen, S.E. (2007). The Arabidopsis LHP1 protein colocalizes with histone H3 Lys27 trimethylation. Nat Struct Mol Biol, 14 (9) : 869-871. (pubmed)

Bouche, N., Lauressergues, D., Gasciolli, V., and Vaucheret, H.(2006). An antagonistic function for Arabidopsis DCL2 in development and a new function for DCL4 in generating viral siRNAs. Embo J, 25 (14) : 3347-3356. (pubmed)

Trouiller, B., Schaefer, D.G., Charlot, F., and Nogue, F. (2006). MSH2 is essential for the preservation of genome integrity and prevents homeologous recombination in the moss Physcomitrella patens. Nucleic Acids Res, 34 (1): 232-242. (pubmed)

Elmayan, T., Proux, F., and Vaucheret, H. (2005). Arabidopsis RPA2: a genetic link among transcriptional gene silencing, DNA repair, and DNA replication. Curr Biol, 15 (21) b : 1919-1925. (pubmed)

Vaucheret, H., Vazquez, F., Crete, P., and Bartel, D.P. (2004). The action of ARGONAUTE1 in the miRNA pathway and its regulation by the miRNA pathway are crucial for plant development. Genes Dev, 18 (10): 1187-1197. (pubmed)

Gaudin, V., Libault, M., Pouteau, S., Juul, T., Zhao, G., Lefebvre, D., and Grandjean, O. (2001). Mutations in LIKE HETEROCHROMATIN PROTEIN 1 affect flowering time and plant architecture in Arabidopsis. Development, 128 (23) : 4847-4858.(pubmed)

Melayah, D., Bonnivard, E., Chalhoub, B., Audeon, C., and Grandbastien, M.A. (2001). The mobility of the tobacco Tnt1 retrotransposon correlates with its transcriptional activation by fungal factors. Plant J, 28 (2): 159-168. (pubmed)

Mourrain, P., Beclin, C., Elmayan, T., Feuerbach, F., Godon, C., Morel, J.B., Jouette, D., Lacombe, A.M., Nikic, S., Picault, N., Remoue, K., Sanial, M., Vo, T.A., and Vaucheret, H. (2000). Arabidopsis SGS2 and SGS3 genes are required for posttranscriptional gene silencing and natural virus resistance. Cell, 101 (5): 533-542. (pubmed)