title: DNA Crossover Motifs Associated with Epigenetic Modifications Delineate Open Chromatin Regions in Arabidopsis.
abstract: The rate of crossover, the reciprocal exchanges of homologous chromosomal segments, is not uniform along chromosomes differing between male and female meiocytes. To better understand the factors regulating this variable landscape, we performed a detailed genetic and epigenetic analysis of 737 crossover events in Arabidopsis thaliana. Crossovers were more frequent than expected in promoters. Three DNA motifs enriched in crossover regions and less abundant in crossover-poor pericentric regions were identified. One of these motifs, the CCN repeat, was previously unknown in plants. The A-rich motif was preferentially associated with promoters, while the CCN repeat and the CTT repeat motifs were preferentially associated with genes. Analysis of epigenetic modifications around the motifs showed, in most cases, a specific epigenetic architecture. For example, we show that there is a peak of nucleosome occupancy and of H3K4me3 around the CCN and CTT repeat motifs while nucleosome occupancy was lowest around the A-rich motif. Cytosine methylation levels showed a gradual decrease within ∼2 kb of the three motifs, being lowest at sites where crossover occurred. This landscape was conserved in the decreased DNA methylation1 mutant. In summary, the crossover motifs are associated with epigenetic landscapes corresponding to open chromatin and contributing to the nonuniformity of crossovers in Arabidopsis.
authors.affiliation: Plant and Environmental Sciences Department, The Weizmann Institute of Science, Rehovot 76100, Israel.
authors.forename: Shay
authors.initials: S
authors.lastname: Shilo
authors.affiliation: Plant and Environmental Sciences Department, The Weizmann Institute of Science, Rehovot 76100, Israel.
authors.forename: Cathy
authors.initials: C
authors.lastname: Melamed-Bessudo
authors.affiliation: Plant and Environmental Sciences Department, The Weizmann Institute of Science, Rehovot 76100, Israel Département de Biologie, Ecole Normale Supérieure de Lyon, Lyon 69007, France.
authors.forename: Yanniv
authors.identifier: http://orcid.org/0000-0001-6092-8386
authors.initials: Y
authors.lastname: Dorone
authors.affiliation: Department of Molecular Genetics, The Weizmann Institute of Science, Rehovot 76100, Israel.
authors.forename: Naama
authors.initials: N
authors.lastname: Barkai
authors.affiliation: Plant and Environmental Sciences Department, The Weizmann Institute of Science, Rehovot 76100, Israel avi.levy@weizmann.ac.il.
authors.forename: Avraham A
authors.identifier: http://orcid.org/0000-0002-3097-1540
authors.initials: AA
authors.lastname: Levy
mesh_terms: D017360:Arabidopsis / Q000235:genetics*; D002843:Chromatin / Q000235:genetics*; D003434:Crossing Over, Genetic; D019175:DNA Methylation; D044127:Epigenesis, Genetic; D008969:Molecular Sequence Data; D059372:Nucleotide Motifs; D011401:Promoter Regions, Genetic; D018911:Trinucleotide Repeats
chemical_list: D002843:Chromatin