Reciprocal exchanges of DNA (crossovers) that occur during meiosis are mandatory to ensure the production of fertile gametes in sexually reproducing species. They also contribute to shuffle parental alleles into new combinations thereby fuelling genetic variation and evolution. However, due to biological constraints, the recombination landscape is highly heterogeneous along the genome which limits the range of allelic combinations and the adaptability of populations. An approach to better understand the constraints on the recombination process is to study how it evolved in the past. In this work we tackled this question by constructing recombination profiles in four diverging bread wheat (Triticum aestivum L.) populations established from 371 landraces genotyped at 200,062 SNPs. We used linkage disequilibrium (LD) patterns to estimate in each population the past distribution of recombination along the genome and characterize its fine-scale heterogeneity. At the megabase scale, recombination rates derived from LD patterns were consistent with family-based estimates obtained from a population of 406 recombinant inbred lines. Among the four populations, recombination landscapes were positively correlated between each other and shared a statistically significant proportion of highly recombinant intervals. However, this comparison also highlighted that the similarity in recombination landscapes between populations was significantly decreasing with their genetic differentiation in most regions of the genome. This observation was found to be robust to SNPs ascertainment and demography and suggests a relatively rapid evolution of factors determining the fine-scale localization of recombination in bread wheat.

中文翻译：

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面包小麦不同种群重组景观的演变


减数分裂过程中发生的 DNA 相互交换（交叉）对于确保有性生殖物种产生可育配子是强制性的。它们还有助于将亲代等位基因重组为新的组合，从而促进遗传变异和进化。然而，由于生物学的限制，基因组上的重组景观具有高度异质性，这限制了等位基因组合的范围和群体的适应性。更好地了解重组过程的限制的一种方法是研究它在过去是如何演变的。在这项工作中，我们通过在 4 个不同的面包小麦 (Triticum aestivum L.) 群体中构建重组谱来解决这个问题，这些群体是由 371 个地方品种（在 200,062 个 SNP 进行基因分型）中建立的。我们使用连锁不平衡（LD）模式来估计每个群体中基因组重组的过去分布，并表征其精细尺度异质性。在兆碱基规模上，源自 LD 模式的重组率与从 406 个重组自交系群体获得的基于家族的估计值一致。在四个群体中，重组景观彼此呈正相关，并且共享高度重组间隔的统计显着比例。然而，这种比较还强调，随着群体在基因组大多数区域的遗传分化，群体之间重组景观的相似性显着降低。发现这一观察对于单核苷酸多态性（SNP）确定和人口统计学来说是稳健的，并且表明决定面包小麦中重组的精细定位的因素的相对快速的演变。