Genome-wide landscape of Arabidopsis meiotic recombination initiation

Abstract

Meiotic recombination is initiated by formation of programmed DNA double strand breaks (DSBs). SPO11 topoisomerase-like complexes catalyze the DSB formation. Frequency of meiotic recombination initiation varies along eukaryotic chromosomes and is controlled by chromatin and DNA sequence. We mapped meiotic DSBs genome wide by purifying and sequencing SPO11-1-oligonucleotides in Arabidopsis. DSB hotspots occurred preferentially in gene promoters, terminators and introns, indicating that nucleosome occupancy is a major determinant of meiotic DSB landscape in plants. Retrotransposons and heterochromatic DNA transposons are coldspots, whereas strong DSB hotspots occur in nucleosome-depleted euchromatic DNA transposons. We also found that epigenetic control of meiotic DSBs occurred in the mutants of DNA methylation, H3K9me2, and H2A.Z deposition. Together, our work reveals complex interactions between chromatin and meiotic DSBs within genes and transposable elements, with significance for the diversity of plant genomes.