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Communication Dans Un Congrès Année : 2009

La première méiose des colzas resynthetisés, un mixeur de génome

Résumé

Chromosomal reshuffling occurs during meiosis in newly created polyploid species in Brassica, contributing to differentiation of parental genomes in the hybrid. In newly synthesized Brassica napus, studies have shown little effect of the very first meiosis in genomic restructuring. However, the frequent and non random fixation of translocations (HNRTs) in early generations of re-synthesized B. napus suppose a major role of the first meiosis in chromosome rearrangements. To study homeologous pairing and remodelling at the creation of the polyploidy, homeologous pair of chromosomes A1-C1 provide an appropriate model, being completely collinear in macrosynteny in B. napus and its progenitors and being the most rearranged pair in natural B. napus haploids. On multiple lineages of synthetic B.napus, we aimed to : (i) Establish the frequent pairing of A1-C1 during the first meiosis of neo-polyploids; (ii) Assess precisely the impact of this meiosis on the nature, the size and the frequency of rearrangements generated on A1 and C1; (iii) Determine the effect of A1-C1 rearrangements on the perturbation of regular meiotic behaviour in contrasted progeny. (i) Various S0 (colchicines doubled hybrids) lineages of resynthesized B. napus have been created from 4 different diploid parents to test genetic background as long as a reciprocal cross to test maternal cytoplasmic effect. By using BAC-FISH (Fluorescent In Situ Hybridisation) approach at meiosis of the first generation S0, it is possible to detect implication of A1-C1 in abnormal chromosome pairing. Evidence for A-C pairing at first meiosis exist, and this work will determine the A1-C1 pairing ability of the progenitors structure. (ii) To assess the impact of first meiosis on genome remodelling in gametes, crosses were performed between the 4 amphidiploids (S0) and a natural B. napus (92 ind. for each). We identified a contrasted behaviour of the B. rapa cytoplasm population, but all had highly frequent inherited chromosomes rearrangements using molecular markers from A1 and C1, and their nature (translocation vs. deletion) will be discussed on a subset of contrasted individuals using BAC FISH differentiating homeologous regions. (iii) By establishing the meiotic behaviour of this subset of plants, we will validate the effect of A1-C1 homogenisation on further genome instability. These data will bring new insight on genome restructuration in polyploids after genome duplication.
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Dates et versions

hal-01594338 , version 1 (26-09-2017)

Identifiants

  • HAL Id : hal-01594338 , version 1
  • PRODINRA : 391762

Citer

Emmanuel Szadkowski, Frederique Eber, Virginie Huteau, Olivier Coriton, Boulos Chalhoub, et al.. La première méiose des colzas resynthetisés, un mixeur de génome. 3. symposium du Groupement De Recherche « Cytogénomique Structurale et Evolutive» (GDR 3041), Institut National de Recherche Agronomique (INRA). UMR Amélioration des Plantes et Biotechnologies Végétales (0118)., Oct 2010, Le Rheu, France. ⟨hal-01594338⟩
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