Véronique Sarilar

Publications (3)17.44 Total impact

• Article: Allopolyploidy has a moderate impact on restructuring at three contrasting transposable element insertion sites in resynthesized Brassica napus allotetraploids.

  Véronique Sarilar, Paulina Martinez Palacios, Agnès Rousselet, Céline Ridel, Matthieu Falque, Frédérique Eber, Anne-Marie Chèvre, Johann Joets, Philippe Brabant, Karine Alix
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  ABSTRACT: The role played by whole-genome duplication (WGD) in evolution and adaptation is particularly well illustrated in allopolyploids, where WGD is concomitant with interspecific hybridization. This 'Genome Shock', usually accompanied by structural and functional modifications, has been associated with the activation of transposable elements (TEs). However, the impact of allopolyploidy on TEs has been studied in only a few polyploid species, and not in Brassica, which has been marked by recurrent polyploidy events. Here, we developed sequence-specific amplification polymorphism (SSAP) markers for three contrasting TEs, and compared profiles between resynthesized Brassica napus allotetraploids and their diploid Brassica progenitors. To evaluate restructuring at TE insertion sites, we scored changes in SSAP profiles and analysed a large set of differentially amplified SSAP bands. No massive structural changes associated with the three TEs surveyed were detected. However, several transposition events, specific to the youngest TE originating from the B. oleracea genome, were identified. Our study supports the hypothesis that TE responses to allopolyploidy are highly specific. The changes observed in SSAP profiles lead us to hypothesize that they may partly result from changes in DNA methylation, questioning the role of epigenetics during the formation of a new allopolyploid genome.
  New Phytologist 02/2013; · 6.64 Impact Factor
• Article: BraSto, a Stowaway MITE from Brassica: recently active copies preferentially accumulate in the gene space.

  Véronique Sarilar, Anne Marmagne, Philippe Brabant, Johann Joets, Karine Alix
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  ABSTRACT: We characterized a Brassica miniature inverted repeat transposable element (MITE) from the Stowaway superfamily, designated BraSto (Bra ssica Sto waway). BraSto copy number was assessed using real-time quantitative PCR in the two diploid species B. rapa (genome A) and B. oleracea (genome C) and the corresponding allotetraploid species B. napus (genome AC). Phylogenetic relationships among a set of 131 BraSto copies were then analyzed. BraSto appears to have been only moderately amplified in the Brassica genome and was still active recently with marks of proliferation in both diploid Brassica species, which diverged 3.75 million years ago, but also in the allotetraploid species after reuniting of the two differentiated genomes. We characterized insertion sites for low-divergence BraSto copies among the gene space of the B. rapa genome using bioinformatics approaches. For BraSto copies localized nearby or within genes, we observed frequent associations of BraSto with putative promoters and regulatory regions of genes, but exclusion from coding regions. In addition, BraSto was significantly similar to several Brassica expressed sequence tags (ESTs), including stress-induced ESTs. We also demonstrated the enrichment of BraSto sequences in binding sites for transcription factors and other regulatory elements. Our results lead to the question of a role for BraSto in the regulation of gene expression: this putative role, if further confirmed experimentally, would help to obtain a new insight into the significance of MITEs in the functional plant genome.
  Plant Molecular Biology 05/2011; 77(1-2):59-75. · 4.15 Impact Factor
• Source

  Available from: Christian Parisod

  Article: Impact of transposable elements on the organization and function of allopolyploid genomes.

  Christian Parisod, Karine Alix, Jérémy Just, Maud Petit, Véronique Sarilar, Corinne Mhiri, Malika Ainouche, Boulos Chalhoub, Marie-Angèle Grandbastien
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  ABSTRACT: Transposable elements (TEs) represent an important fraction of plant genomes and are likely to play a pivotal role in fuelling genome reorganization and functional changes following allopolyploidization. Various processes associated with allopolyploidy (i.e. genetic redundancy, bottlenecks during the formation of allopolyploids or genome shock following genome merging) may allow accumulation of TE insertions. Our objective in carrying out a survey of the literature and a comparative analysis across different allopolyploid systems is to shed light on the structural, epigenetic and functional modifications driven by TEs during allopolyploidization and subsequent diploidization. The available evidence indicates that TE proliferation in the short or the long term after allopolyploidization may be restricted to a few TEs, in specific polyploid systems. By contrast, data indicate major structural changes in the TE genome fraction immediately after allopolyploidization, mainly through losses of TE sequences as a result of recombination. Emerging evidence also suggests that TEs are targeted by substantial epigenetic changes, which may impact gene expression and genome stability. Furthermore, TEs may directly or indirectly support the evolution of new functionalities in allopolyploids during diploidization. All data stress allopolyploidization as a shock associated with drastic genome reorganization. Mechanisms controlling TEs during allopolyploidization as well as their impact on diploidization are discussed.
  New Phytologist 12/2009; 186(1):37-45. · 6.64 Impact Factor