Meiosis recombines genetic variation and influences eukaryote genome evolution. During meiosis, DNA double-strand breaks (DSBs) enter interhomolog repair to yield crossovers and non-crossovers. DSB repair occurs as replicated sister chromatids are connected to a polymerized axis. Cohesin rings containing the REC8-kleisin subunit bind sister chromatids and anchor chromosomes to the axis. Here we report the genomic landscape of REC8 using ChIP-seq in Arabidopsis. REC8 associates with regions of high nucleosome occupancy in multiple chromatin states, including histone methylation at H3K4 (expressed genes), H3K27 (silent genes) and H3K9 (silent transposons). REC8 enrichment is associated with suppression of meiotic DSBs and crossovers at the chromosome and fine scales. As REC8 enrichment is greatest in transposon-dense heterochromatin, we repeated ChIP-seq in kyp suvh5 suvh6 H3K9me2 mutants. Surprisingly, REC8 enrichment is maintained in kyp suvh5 suvh6 heterochromatin and no defects in centromeric cohesion were observed. REC8 occupancy within genes anti-correlates with transcription and is reduced in COPIA transposons that reactivate expression in kyp suvh5 suvh6. Abnormal axis structures form in rec8 that recruit DSB-associated protein foci and undergo synapsis, which is followed by chromosome fragmentation. Therefore, REC8 occupancy correlates with multiple chromatin states and is required to organize meiotic chromosome architecture and interhomolog recombination.

减数分裂重组遗传变异并影响真核生物基因组进化。在减数分裂期间，DNA双链断裂（DSB）进入同源同源物修复，从而产生交叉和非交叉。当复制的姐妹染色单体连接到聚合轴时，发生DSB修复。含有REC8-kleisin亚基的粘着素环将姐妹染色单体结合并锚定染色体至轴。在这里，我们报告了拟南芥中使用ChIP-seq的REC8的基因组格局。REC8与处于多个染色质状态的高核小体占有率区域相关，包括H3K4（表达的基因），H3K27（沉默的基因）和H3K9（沉默的转座子）处的组蛋白甲基化。REC8富集与减数分裂DSB的抑制和染色体和精细尺度上的交叉相关。由于REC8富集在转座子致密异染色质中最大，我们在kyp suvh5 suvh6 H3K9me2突变体中重复了ChIP-seq。出人意料的是，在kyp suvh5 suvh6异染色质中保持了REC8富集，未观察到着丝粒内聚力缺陷。基因中的REC8占用与转录反相关，并且在重新激活kyp suvh5 suvh6中表达的COPIA转座子中减少。在rec8中形成异常的轴结构，该结构募集与DSB相关的蛋白灶并进行突触，随后发生染色体断裂。因此，REC8占用与多个染色质状态相关，是组织减数分裂染色体结构和同源重组的必需条件。基因中的REC8占用与转录反相关，并且在重新激活kyp suvh5 suvh6中表达的COPIA转座子中减少。在rec8中形成异常的轴结构，该结构募集与DSB相关的蛋白灶并进行突触，随后发生染色体断裂。因此，REC8占用与多个染色质状态相关，是组织减数分裂染色体结构和同源重组的必需条件。基因中的REC8占用与转录反相关，并且在重新激活kyp suvh5 suvh6中表达的COPIA转座子中减少。在rec8中形成异常的轴结构，该结构募集与DSB相关的蛋白灶并进行突触，随后发生染色体断裂。因此，REC8占用与多个染色质状态相关，是组织减数分裂染色体结构和同源重组的必需条件。