Impact of DNA methylation on meiotic recombination in Arabidopsis thaliana – MeioMeth

Genetic maps will be established using natural variations of DNA sequences among populations of plants. More local modifications will be studied using the reassociation of linked fluorescent markers on chromosome segments. Ponctual modifications of recombination rates will be studied by molecular biology techniques that allow the analysis at precise position on the genome.

Since the beginning of the ANR (1-10-2011), we have produced the matreial needed for the project. Unfortunately, since the beginning of 2012, 4 papers have been published on the tpoic using appraoches that are similar to ours. The results obtained are concording and show that DNA methylation has a weak impact on meiotc recombination. Our preliminary results go in the same way, Thus we have decided to stop this part of the project. However, we are going to coninue the analysis on DNA methylation and meiotic recombination hotspots as it has not been studied in the published works (the tools used would not allow to see an effect) and as it is with a similiar analysis that an effect has been observed on a filamentus fungus

The analysis of the effect of DNA methylation on meiotic recombinaiton hotpsot is beiing done

ND

A key aspect of meiotic recombination is the formation of crossovers (COs), which is essential for the proper segregation of homologous chromosomes at opposite poles during the first meiotic division. In all species where this has been studied, including the reference plant Arabidopsis thaliana, CO frequency and distribution vary along chromosomes. This variation has major impact in plant and animal breeding, as it affects the efficiency with which genes of agronomical interest can be introgressed.
Considerable progress has been made over the last ten years in our molecular understanding of CO formation. However, we still know very little about the factors that control the non-random distribution of COs along chromosomes, except that both DNA sequence and chromatin are likely involved.
Here, we propose to address specifically the effect of DNA methylation, a classical epigenetic mark, on CO frequency and distribution in Arabidopsis. To this end, we will take advantage of a population of epigenetic recombinant inbred lines (epiRILs) that are genotypically wild type but differ from each other by their pattern of DNA methylation at many loci across the genome. The epiRILs will serve as parents for a series of crosses designed to investigate genome wide different aspects of the impact of DNA methylation on CO. The main objectives of the project are 1) to test the effect of DNA hypomethylation on the frequency and distribution of COs in a sex-dependent manner; 2) to distinguish local and long-range effects of DNA hypomethylation and 3) to analyze the effect of local and forced DNA methylation of well-characterized recombination hotspots on CO frequency.
To our knowledge, this project is the first of its kind and should therefore provide major insights into chromatin-level control of CO formation in higher eukaryotes. In turn, this new knowledge may pave the way for the development of breeding strategies based on the modulation of CO frequency and position through targeted changes in DNA methylation.