马克斯·普朗克植物育种研究所C. M. Ritz团队近日取得一项新成果。经过不懈努力，他们的研究报道了五倍体犬鼠的双峰着丝粒揭示了它们独特的减数分裂。这一研究成果于2025年6月18日发表在国际顶尖学术期刊《自然》上。

在这里，该团队分析了三种五倍体狗狗的单倍型染色体水平基因组组装。亚基因组相位显示一个二价形成的亚基因组具有两个高度纯合的染色体组，而三个不同的亚基因组缺乏同源的伴侣，因此解释了它们的减数分裂行为。染色体合性、系统发育关系和着丝粒组成的比较分析表明，亚基因组起源于蔷薇属的两个不同分支。花粉基因组分析表明，来自不同进化起源的亚基因组形成二价体，支持犬鼠的多个起源，并突出了亚基因组贡献的差异。课题组研究人员发现，形成二价体的着丝粒富含ATHILA反转录转座子，与主要存在于单价体中的较大的串联重复体为基础的着丝粒形成对比。这种着丝粒结构的双峰性可能有助于雌性减数分裂过程中的单价驱动。他们的发现为犬鼠独特的生殖策略提供了见解，促进了他们对基因组进化、着丝粒多样性和具有不对称遗传系统的生物减数分裂机制的理解。

据悉，有性生殖依靠减数分裂染色体配对形成二价体，由于存在多个亚基因组，这一过程在多倍体中比较复杂。不均匀倍性主要是由于减数分裂期间染色体配对和分离不平衡而导致不育。然而，五倍体狗鼬（Rosa节，犬科动物;2n=5x=35)通过一种独特的机制实现稳定的有性生殖：14条染色体形成二价体并通过双亲遗传，而其余21条染色体以一价体形式由母亲遗传。尽管研究了一个多世纪，着丝粒在这一过程中的作用仍不清楚。

附：英文原文

Title: Bimodal centromeres in pentaploid dogroses shed light on their unique meiosis

Author: Herklotz, V., Zhang, M., Nascimento, T., Kalfusov, R., Lunerov, J., Fuchs, J., Harpke, D., Huettel, B., Pfordt, U., Wissemann, V., Kovak, A., Marques, A., Ritz, C. M.

Issue&Volume: 2025-06-18

Abstract: Sexual reproduction relies on meiotic chromosome pairing to form bivalents, a process that is complicated in polyploids owing to the presence of multiple subgenomes1. Uneven ploidy mostly results in sterility due to unbalanced chromosome pairing and segregation during meiosis. However, pentaploid dogroses (Rosa sect. Caninae; 2n=5x=35) achieve stable sexual reproduction through a unique mechanism: 14 chromosomes form bivalents and are transmitted biparentally, while the remaining 21 chromosomes are maternally inherited as univalents2,3. Despite being studied for over a century, the role of centromeres in this process has remained unclear. Here we analyse haplotype-resolved chromosome-level genome assemblies for three pentaploid dogroses. Subgenome phasing revealed a bivalent-forming subgenome with two highly homozygous chromosome sets and three divergent subgenomes lacking homologous partners, therefore explaining their meiotic behaviour. Comparative analyses of chromosome synteny, phylogenetic relationships and centromere composition indicate that the subgenomes originated from two divergent clades of the genus Rosa. Pollen genome analysis shows that subgenomes from different evolutionary origins form bivalents, supporting multiple origins of dogroses and highlighting variation in subgenome contributions. We reveal that bivalent-forming centromeres are enriched with ATHILA retrotransposons, contrasting with larger tandem-repeat-based centromeres mainly found in univalents. This centromere structural bimodality possibly contributes to univalent drive during female meiosis. Our findings provide insights into the unique reproductive strategies of dogroses, advancing our understanding of genome evolution, centromere diversity and meiotic mechanisms in organisms with asymmetrical inheritance systems.

DOI: 10.1038/s41586-025-09171-z

Source: https://www.nature.com/articles/s41586-025-09171-z