During meiosis, DNA double‐strand breaks undergo interhomolog repair to yield crossovers between homologous chromosomes. To investigate how interhomolog sequence polymorphism affects crossovers, we sequenced multiple recombinant populations of the model plant Arabidopsis thaliana. Crossovers were elevated in the diverse pericentromeric regions, showing a local preference for polymorphic regions. We provide evidence that crossover association with elevated diversity is mediated via the Class I crossover formation pathway, although very high levels of diversity suppress crossovers. Interhomolog polymorphism causes mismatches in recombining molecules, which can be detected by MutS homolog (MSH) mismatch repair protein heterodimers. Therefore, we mapped crossovers in a msh2 mutant, defective in mismatch recognition, using multiple hybrid backgrounds. Although total crossover numbers were unchanged in msh2 mutants, recombination was remodelled from the diverse pericentromeres towards the less‐polymorphic sub‐telomeric regions. Juxtaposition of megabase heterozygous and homozygous regions causes crossover remodelling towards the heterozygous regions in wild type Arabidopsis, but not in msh2 mutants. Immunostaining showed that MSH2 protein accumulates on meiotic chromosomes during prophase I, consistent with MSH2 regulating meiotic recombination. Our results reveal a pro‐crossover role for MSH2 in regions of higher sequence diversity in A. thaliana.

中文翻译：

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MSH2塑造了拟南芥中与同源多态性有关的减数分裂交叉景观。

在减数分裂过程中，DNA双链断裂经历同源间修复，从而在同源染色体之间产生交叉。为了研究同源序列间的多态性如何影响交叉，我们对模型植物拟南芥的多个重组种群进行了测序。交叉在不同的着丝粒区域中升高，显示出对多态区域的局部偏好。我们提供的证据表明，具有较高多样性的交叉关联是通过I类交叉形成途径介导的，尽管很高的多样性抑制了交叉。同源多态性导致重组分子错配，可以通过MutS同源物（MSH）错配修复蛋白异二聚体检测到。因此，我们在msh2中映射了分频器突变体，使用多个混合背景在错配识别方面存在缺陷。尽管在msh2突变体中总交换数没有变化，但重组已从多样的着丝粒向着不太多态的亚端粒区域进行了重塑。megabase杂合区和纯合区的并置导致在野生型拟南芥中向杂合区的交叉重塑，但在msh2突变体中则没有。免疫染色表明，MSH2蛋白在前期I期间积累在减数分裂染色体上，与MSH2调节减数分裂重组一致。我们的结果揭示了拟南芥中较高序列多样性的区域中MSH2的亲交叉作用。