White campion (Silene latifolia, Caryophyllaceae) was the first vascular plant where sex chromosomes were discovered. This species is a classic model for studies on plant sex chromosomes due to presence of large, clearly distinguishable X and Y chromosomes that originated de novo about 11 million years ago (mya), but lack of genomic resources for this relatively large genome (∼2.8 Gb) remains a significant hurdle. Here we report S. latifolia female genome assembly integrated with sex-specific genetic maps of this species, focusing on sex chromosomes and their evolution. The analysis reveals a highly heterogeneous recombination landscape with strong reduction in recombination rate in the central parts of all chromosomes. Recombination on the X chromosome in female meiosis primarily occurs at the very ends, and over 85% of the X chromosome length is located in a massive (∼330 Mb) gene-poor, rarely recombining pericentromeric region (Xpr). The results indicate that the non-recombining region on the Y chromosome (NRY) initially evolved in a relatively small (∼15 Mb), actively recombining region at the end of the q-arm, possibly as a result of inversion on the nascent X chromosome. The NRY expanded about 6 mya via linkage between the Xpr and the sex-determining region, which may have been caused by expanding pericentromeric recombination suppression on the X chromosome. These findings shed light on the origin of sex chromosomes in S. latifolia and yield genomic resources to assist ongoing and future investigations into sex chromosome evolution.

白坎皮（Silene latifolia，石竹科）是第一个发现性染色体的维管植物。该物种是植物性染色体研究的经典模型，因为存在大约 1100 万年前从头起源的大型、可清晰区分的 X 和 Y 染色体 (mya)，但缺乏这个相对较大的基因组的基因组资源 (∼2.8 Gb) 仍然是一个重大障碍。在这里我们报告S. latifolia女性基因组组装与该物种的性别特异性遗传图谱整合，重点关注性染色体及其进化。分析揭示了高度异质的重组景观，所有染色体中心部分的重组率大幅降低。雌性减数分裂中 X 染色体上的重组主要发生在末端，超过 85% 的 X 染色体长度位于大量（∼330 Mb）基因贫乏、很少重组的着丝粒周围区域 (Xpr)。结果表明，Y 染色体上的非重组区域 (NRY) 最初是在 q 臂末端相对较小 (∼15 Mb) 的活跃重组区域中进化的，这可能是新生 X 染色体倒位的结果。染色体。NRY 通过 Xpr 和性别决定区之间的连接扩增了约 6 mya，这可能是由于 X 染色体上着丝粒周围重组抑制的扩大所致。这些发现揭示了性染色体的起源S. latifolia并产生基因组资源，以协助正在进行和未来的性染色体进化研究。