Department of Molecular Biology, Max Planck Institute for Biology Tübingen, Tübingen, 72076, Germany.
Genome Biol. 2024 Sep 16;25(1):244. doi: 10.1186/s13059-024-03388-3.
Telomeric repeat arrays at the ends of chromosomes are highly dynamic in composition, but their repetitive nature and technological limitations have made it difficult to assess their true variation in genome diversity surveys.
We have comprehensively characterized the sequence variation immediately adjacent to the canonical telomeric repeat arrays at the very ends of chromosomes in 74 genetically diverse Arabidopsis thaliana accessions. We first describe several types of distinct telomeric repeat units and then identify evolutionary processes such as local homogenization and higher-order repeat formation that shape diversity of chromosome ends. By comparing largely isogenic samples, we also determine repeat number variation of the degenerate and variant telomeric repeat array at both the germline and somatic levels. Finally, our analysis of haplotype structure uncovers chromosome end-specific patterns in the distribution of variant telomeric repeats, and their linkage to the more proximal non-coding region.
Our findings illustrate the spectrum of telomeric repeat variation at multiple levels in A. thaliana-in germline and soma, across all chromosome ends, and across genetic groups-thereby expanding our knowledge of the evolution of chromosome ends.
染色体末端的端粒重复序列在组成上具有高度动态性，但由于其重复性质和技术限制，很难在基因组多样性调查中评估其真实的变异情况。
我们全面描述了 74 个遗传多样性的拟南芥品系中染色体末端典型端粒重复序列附近的序列变异。我们首先描述了几种不同的端粒重复单元，然后确定了塑造染色体末端多样性的进化过程，如局部同质化和高阶重复形成。通过比较基本同基因型的样本，我们还确定了生殖系和体细胞水平上退化和变体端粒重复序列的重复数变异。最后，我们对单倍型结构的分析揭示了变体端粒重复在分布上的染色体末端特异性模式，以及它们与更接近的非编码区的连锁。
我们的研究结果说明了拟南芥中多个层次的端粒重复变异情况——在生殖系和体细胞中，在所有染色体末端，以及在遗传群体中——从而扩展了我们对染色体末端进化的认识。
