Table_S7_linear_model results.xlsx from Recombination landscape dimorphism and sex chromosome evolution in the dioecious plant <i>Rumex hastatulus</i>

There is growing evidence from diverse taxa for sex differences in the genomic landscape of recombination, but the causes and consequences of these differences remain poorly understood. Strong recombination landscape dimorphism between the sexes could have important implications for the dynamics of sex chromosome evolution because low recombination in the heterogametic sex can favour the spread of sexually antagonistic alleles. Here, we present a sex-specific linkage map and revised genome assembly of <i>Rumex hastatulus</i> and provide the first evidence and characterization of sex differences in recombination landscape in a dioecious plant. We present data on significant sex differences in recombination, with regions of very low recombination in males covering over half of the genome. This pattern is evident on both sex chromosomes and autosomes, suggesting that pre-existing differences in recombination may have contributed to sex chromosome formation and divergence. Our analysis of segregation distortion suggests that haploid selection due to pollen competition occurs disproportionately in regions with low male recombination. We hypothesize that sex differences in the recombination landscape have contributed to the formation of a large heteromorphic pair of sex chromosomes in <i>R. hastatulus</i>, but more comparative analyses of recombination will be important to investigate this hypothesis further.This article is part of the theme issue ‘Sex determination, sex chromosome evolution, and the role of sexual differentiation in land plants’.

目前已有越来越多来自不同类群的研究证据表明，重组基因组格局存在性别差异，但此类差异的成因与后果仍未得到充分阐释。两性间显著的重组格局二态性可能对性染色体演化动态产生重要影响——异配性别（heterogametic sex）中的低重组水平会促进性拮抗等位基因的扩散。本研究构建了长柄酸模（Rumex hastatulus）的性别特异性连锁图谱与修订版基因组组装，并首次在雌雄异株植物（dioecious plant）中揭示并表征了重组格局的性别差异。本研究数据显示，两性重组存在显著差异：雄性体内重组率极低的区域覆盖了超过一半的基因组。该特征在性染色体与常染色体（autosomes）上均有体现，表明重组率的预先差异可能推动了性染色体的形成与分化。我们对分离扭曲（segregation distortion）的分析表明，由花粉竞争（pollen competition）引发的单倍体选择（haploid selection）在雄性低重组区域的发生比例不成比例地偏高。我们提出假说：重组格局的性别差异推动了长柄酸模中大型异形性染色体对的形成，但未来需开展更多重组相关比较分析以进一步验证该假说。本文隶属于"性别决定、性染色体演化及陆地植物性别分化作用"专题栏目。