Role of epigenetic and tranScripTomIc modifications in inteRspecific hybRids In chaNginG the rules of crossover regulation: the Brassica model


Meiotic recombination is the main mechanism allowing reshuffling the genetic diversity at each generation. It is thus critical to the introduction of genes of interest into crops, and in the process of reducing their environmental footprint, while at the same time maintaining both yield and quality. However, as meiosis is strictly controlled, the introduction of alleles of interest may take a decade and cannot be applied to the genomic regions that are deprived of recombination. Indeed, only one and rarely three crossovers (COs) per homologous chromosomes are formed during meiosis. These COs are not randomly distributed along the chromosomes (mainly in distal regions of the chromosomes). Recently, we showed that it is possible to change drastically both the number and localization of COs through interspecific hybridization and aneuploidy. By crossing the allopolyploid oilseed rape (Brassica napus, AACC, 2n=4x=38) crop with one of its progenitor, B. rapa (AA, 2n=2x=20), we obtained allotriploid hybrids (AAC, 2n=3x=29). In these hybrids, we observed a 3.4x increase of COs number and a modification of the CO landscape with CO formation in normally cold regions (pericentromeres) of the A chromosomes. The mechanisms involved in this modification of meiosis regulation remains totally unknown. In addition, it remains to be deciphered if these modified recombination rules may be maintained or reversed to normal.


The objectives of this project are to answer the following two questions:

1) What is the role of epigenomic/transcriptomic modifications in changing the recombination rules?
To answer this question, we will perform comparative genomic analyses (BS-Seq and RNA-Seq from flower buds) to explore the potential role of DNA methylation and transcriptomic modifications in modifying the recombination rules.

2) Can these modified recombination rules be maintained or reversed back to normal?
To answer this second question, we will combine genetic mapping and immunostaining approaches to determine the fate of this unique recombination pattern in allotriploid progenies.

Results from this project will provide major knowledge highlighting the natural mechanisms involved in meiotic (de)regulation, and will generate a major translational impact by providing novel and effective breeding strategies in a major crop, oilseed rape.



Modification date : 06 February 2023 | Publication date : 31 January 2022 | Redactor : IGEPP