Evolution of the spinach sex-linked region within a rarely recombining pericentromeric region

文献类型： 外文期刊

第一作者： She, Hongbing

作者： She, Hongbing;Liu, Zhiyuan;Xu, Zhaosheng;Zhang, Helong;Cheng, Feng;Wu, Jian;Wang, Xiaowu;Qian, Wei;Li, Shufen;Deng, Chuanliang;Gao, Wujun;Charlesworth, Deborah

作者机构：

期刊名称：PLANT PHYSIOLOGY （ 影响因子：7.4； 五年影响因子：8.7 ）

ISSN： 0032-0889

年卷期： 2023 年

页码：

收录情况： SCI

摘要： Sex chromosomes have evolved independently in many different plant lineages. Here, we describe reference genomes for spinach (Spinacia oleracea) X and Y haplotypes by sequencing homozygous XX females and YY males. The long arm of 185-Mb chromosome 4 carries a 13-Mb X-linked region (XLR) and 24.1-Mb Y-linked region (YLR), of which 10 Mb is Y specific. We describe evidence that this reflects insertions of autosomal sequences creating a "Y duplication region" or "YDR" whose presence probably directly reduces genetic recombination in the immediately flanking regions, although both the X and Y sex-linked regions are within a large pericentromeric region of chromosome 4 that recombines rarely in meiosis of both sexes. Sequence divergence estimates using synonymous sites indicate that YDR genes started diverging from their likely autosomal progenitors about 3 MYA, around the time when the flanking YLR stopped recombining with the XLR. These flanking regions have a higher density of repetitive sequences in the YY than the XX assembly and include slightly more pseudogenes compared with the XLR, and the YLR has lost about 11% of the ancestral genes, suggesting some degeneration. Insertion of a male-determining factor would have caused Y linkage across the entire pericentromeric region, creating physically small, highly recombining, terminal pseudoautosomal regions. These findings provide a broader understanding of the origin of sex chromosomes in spinach. The spinach X and Y haplotypes are obtained through de novo homozygous XX female and YY males, deciphering the origin and evolution of sex chromosome in Spinacia oleracea.

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