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Master Thesis

La distribution des évènements de crossing-over, un paramètre modulable chez les Brassicas

Abstract : Meiotic recombination by Crossover (CO) is the primary mechanism for the genetic mixing of diversity in the production of offspring in breeding programs. However, the number and distribution of COs are strictly regulated. Indeed, there is still a CO per chromosome, but rarely more and their distribution is not uniform along the chromosome. Yet in Brassicas, it is possible to increase by a factor of 6 the rate of recombination between the genomes A in AAC triploid hybrid (2n = 29) compared with the AA diploid (2n = 20), due to the nature of C chromosomes in addition, particularly to the C9. It is now possible to make a physical connection with these changes in the frequency of recombination with the recent sequencing of the genomes of B. rapa and B. napus. The purpose of this study is to understand how the genomic structure of chromosome A07 determines the formation of COs and to determine the effect of the addition of C9 chromosome and the 9 chromosomes C in a diploid AA on COs distribution. To make this, we have (1) selected three areas contrasted for the frequency of recombination on chromosome A07 on AA, AA+1C9 and AAC populations, and (2) densified and mapped microsatellite markers physically anchored every 300 Kb to characterize these areas. We have shown that the distribution of COs along chromosome A07 is explained by the genomic structure in AA diploid. New points of recombination occur in the presence of C9 chromosome and 9 chromosome C in cold regions in the AA control and especially in pericentromeric regions. These findings offer the prospect of breaking some linkage disequilibrium and stir retained loci in plant breeding.
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Master Thesis
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Alexandre Pelé. La distribution des évènements de crossing-over, un paramètre modulable chez les Brassicas. Sciences agricoles. 2013. ⟨dumas-00966024⟩

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