title: The Impact of Open Pollination on the Structural Evolutionary Dynamics, Meiotic Behavior, and Fertility of Resynthesized AllotetraploidBrassica napusL.
abstract: Allopolyploidy, which results from the merger and duplication of two divergent genomes, has played a major role in the evolution and diversification of flowering plants. The genomic changes that occur in resynthesized or natural neopolyploids have been extensively studied, but little is known about the effects of the reproductive mode in the initial generations that may precede its successful establishment. To truly reflect the early generations of a nascent polyploid, two resynthesized allotetraploidBrassica napuspopulations were obtained for the first time by open pollination. In these populations, we detected a much lower level of aneuploidy (third generation) compared with those previously published populations obtained by controlled successive selfing. We specifically studied 33 resynthesizedB. napusindividuals from our two open pollinated populations, and showed that meiosis was affected in both populations. Their genomes were deeply shuffled after allopolyploidization: up to 8.5 and 3.5% of the C and A subgenomes were deleted in only two generations. The identified deletions occurred mainly at the distal part of the chromosome, and to a significantly greater extent on the C rather than the A subgenome. Using FluorescentIn SituHybridization (BAC-FISH), we demonstrated that four of these deletions corresponded to fixed translocations (via homeologous exchanges). We were able to evaluate the size of the structural variations and their impact on the whole genome size, gene content, and allelic diversity. In addition, the evolution of fertility was assessed, to better understand the difficulty encountered by novel polyploid individuals before the putative formation of a novel stable species.
authors.affiliation: Institut de Génétique, Environnement et Protection des Plantes (IGEPP), Institut National De La Recherche Agronomique (INRA), Université de Rennes 1, 35650 Le Rheu, France mathieu.rousseau-gueutin@inra.fr anne-marie.chevre@inra.fr.
authors.forename: Mathieu
authors.initials: M
authors.lastname: Rousseau-Gueutin
authors.affiliation: Institut de Génétique, Environnement et Protection des Plantes (IGEPP), Institut National De La Recherche Agronomique (INRA), Université de Rennes 1, 35650 Le Rheu, France.
authors.forename: Jérôme
authors.initials: J
authors.lastname: Morice
authors.affiliation: Institut de Génétique, Environnement et Protection des Plantes (IGEPP), Institut National De La Recherche Agronomique (INRA), Université de Rennes 1, 35650 Le Rheu, France.
authors.forename: Olivier
authors.initials: O
authors.lastname: Coriton
authors.affiliation: Institut de Génétique, Environnement et Protection des Plantes (IGEPP), Institut National De La Recherche Agronomique (INRA), Université de Rennes 1, 35650 Le Rheu, France.
authors.forename: Virginie
authors.initials: V
authors.lastname: Huteau
authors.affiliation: Institut de Génétique, Environnement et Protection des Plantes (IGEPP), Institut National De La Recherche Agronomique (INRA), Université de Rennes 1, 35650 Le Rheu, France.
authors.forename: Gwenn
authors.initials: G
authors.lastname: Trotoux
authors.affiliation: Institut de Génétique, Environnement et Protection des Plantes (IGEPP), Institut National De La Recherche Agronomique (INRA), Université de Rennes 1, 35650 Le Rheu, France.
authors.forename: Sylvie
authors.initials: S
authors.lastname: Nègre
authors.affiliation: Institut de Génétique, Environnement et Protection des Plantes (IGEPP), Institut National De La Recherche Agronomique (INRA), Université de Rennes 1, 35650 Le Rheu, France.
authors.forename: Cyril
authors.initials: C
authors.lastname: Falentin
authors.affiliation: Institut de Génétique, Environnement et Protection des Plantes (IGEPP), Institut National De La Recherche Agronomique (INRA), Université de Rennes 1, 35650 Le Rheu, France.
authors.forename: Gwennaëlle
authors.initials: G
authors.lastname: Deniot
authors.affiliation: Institut de Génétique, Environnement et Protection des Plantes (IGEPP), Institut National De La Recherche Agronomique (INRA), Université de Rennes 1, 35650 Le Rheu, France.
authors.forename: Marie
authors.initials: M
authors.lastname: Gilet
authors.affiliation: Institut de Génétique, Environnement et Protection des Plantes (IGEPP), Institut National De La Recherche Agronomique (INRA), Université de Rennes 1, 35650 Le Rheu, France.
authors.forename: Frédérique
authors.initials: F
authors.lastname: Eber
authors.affiliation: Institut de Génétique, Environnement et Protection des Plantes (IGEPP), Institut National De La Recherche Agronomique (INRA), Université de Rennes 1, 35650 Le Rheu, France.
authors.forename: Alexandre
authors.initials: A
authors.lastname: Pelé
authors.affiliation: French Plant Genomic Resource Center (CNRGV), INRA, 31326 Castanet Tolosan Cedex, France.
authors.forename: Sonia
authors.initials: S
authors.lastname: Vautrin
authors.affiliation: French Plant Genomic Resource Center (CNRGV), INRA, 31326 Castanet Tolosan Cedex, France.
authors.forename: Joëlle
authors.initials: J
authors.lastname: Fourment
authors.affiliation: Institut de Génétique, Environnement et Protection des Plantes (IGEPP), Institut National De La Recherche Agronomique (INRA), Université de Rennes 1, 35650 Le Rheu, France.
authors.forename: Maryse
authors.initials: M
authors.lastname: Lodé
authors.affiliation: French Plant Genomic Resource Center (CNRGV), INRA, 31326 Castanet Tolosan Cedex, France.
authors.forename: Hélène
authors.initials: H
authors.lastname: Bergès
authors.affiliation: Institut de Génétique, Environnement et Protection des Plantes (IGEPP), Institut National De La Recherche Agronomique (INRA), Université de Rennes 1, 35650 Le Rheu, France mathieu.rousseau-gueutin@inra.fr anne-marie.chevre@inra.fr.
authors.forename: Anne-Marie
authors.initials: AM
authors.lastname: Chèvre
mesh_terms: D029688:Brassica napus / Q000235:genetics; D032461:Chromosomes, Plant / Q000235:genetics; D019143:Evolution, Molecular; D005298:Fertility / Q000235:genetics; D018745:Genome, Plant; D006824:Hybridization, Genetic; D017404:In Situ Hybridization, Fluorescence; D008540:Meiosis / Q000235:genetics*; D054817:Pollination / Q000235:genetics*; D011123:Polyploidy
keywords: Brassica napus; allopolyploidy; fertility; genome dynamic; meiotic behavior