title: Features of the Arabidopsis recombination landscape resulting from the combined loss of sequence variation and DNA methylation.
abstract: The rate of meiotic crossing over (CO) varies considerably along chromosomes, leading to marked distortions between physical and genetic distances. The causes underlying this variation are being unraveled, and DNA sequence and chromatin states have emerged as key factors. However, the extent to which the suppression of COs within the repeat-rich pericentromeric regions of plant and mammalian chromosomes results from their high level of DNA polymorphisms and from their heterochromatic state, notably their dense DNA methylation, remains unknown. Here, we test the combined effect of removing sequence polymorphisms and repeat-associated DNA methylation on the meiotic recombination landscape of an Arabidopsis mapping population. To do so, we use genome-wide DNA methylation data from a large panel of isogenic epigenetic recombinant inbred lines (epiRILs) to derive a recombination map based on 126 meiotically stable, differentially methylated regions covering 81.9% of the genome. We demonstrate that the suppression of COs within pericentromeric regions of chromosomes persists in this experimental setting. Moreover, suppression is reinforced within 3-Mb regions flanking pericentromeric boundaries, and this effect appears to be compensated by increased recombination activity in chromosome arms. A direct comparison with 17 classical Arabidopsis crosses shows that these recombination changes place the epiRILs at the boundary of the range of natural variation but are not severe enough to transgress that boundary significantly. This level of robustness is remarkable, considering that this population represents an extreme with key recombination barriers having been forced to a minimum.
authors.affiliation: Groningen Bioinformatics Centre,  University of Groningen, 9747 AG Groningen,  The Netherlands.
authors.forename: Maria
authors.initials: M
authors.lastname: Colomé-Tatché
authors.forename: Sandra
authors.initials: S
authors.lastname: Cortijo
authors.forename: René
authors.initials: R
authors.lastname: Wardenaar
authors.forename: Lionel
authors.initials: L
authors.lastname: Morgado
authors.forename: Benoit
authors.initials: B
authors.lastname: Lahouze
authors.forename: Alexis
authors.initials: A
authors.lastname: Sarazin
authors.forename: Mathilde
authors.initials: M
authors.lastname: Etcheverry
authors.forename: Antoine
authors.initials: A
authors.lastname: Martin
authors.forename: Suhua
authors.initials: S
authors.lastname: Feng
authors.forename: Evelyne
authors.initials: E
authors.lastname: Duvernois-Berthet
authors.forename: Karine
authors.initials: K
authors.lastname: Labadie
authors.forename: Patrick
authors.initials: P
authors.lastname: Wincker
authors.forename: Steven E
authors.initials: SE
authors.lastname: Jacobsen
authors.forename: Ritsert C
authors.initials: RC
authors.lastname: Jansen
authors.forename: Vincent
authors.initials: V
authors.lastname: Colot
authors.forename: Frank
authors.initials: F
authors.lastname: Johannes
mesh_terms: D017360:Arabidopsis / Q000235:genetics*; D003433:Crosses, Genetic; D003434:Crossing Over, Genetic / Q000235:genetics*; D019175:DNA Methylation / Q000235:genetics*; D044127:Epigenesis, Genetic / Q000235:genetics*; D020869:Gene Expression Profiling; D014644:Genetic Variation