A near-complete genome assembly of Brassica rapa provides new insights into the evolution of centromeres

文献类型： 外文期刊

第一作者： Zhang, Lei

作者： Zhang, Lei;Liang, Jianli;Chen, Haixu;Zhang, Zhicheng;Wu, Jian;Wang, Xiaowu

作者机构：

关键词： Brassica rapa; near-complete genome assembly; LTRs; centromeres; evolution

期刊名称：PLANT BIOTECHNOLOGY JOURNAL （ 影响因子：13.8； 五年影响因子：13.2 ）

ISSN： 1467-7644

年卷期： 2023 年

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收录情况： SCI

摘要： Brassica rapa comprises many important cultivated vegetables and oil crops. However, Chiifu v3.0, the current B. rapa reference genome, still contains hundreds of gaps. Here, we presented a near-complete genome assembly of B. rapa Chiifu v4.0, which was 424.59 Mb with only two gaps, using Oxford Nanopore Technology (ONT) ultralong-read sequencing and Hi-C technologies. The new assembly contains 12 contigs, with a contig N50 of 38.26 Mb. Eight of the ten chromosomes were entirely reconstructed in a single contig from telomere to telomere. We found that the centromeres were mainly invaded by ALE and CRM long terminal repeats (LTRs). Moreover, there is a high divergence of centromere length and sequence among B. rapa genomes. We further found that centromeres are enriched for Copia invaded at 0.14 MYA on average, while pericentromeres are enriched for Gypsy LTRs invaded at 0.51 MYA on average. These results indicated the different invasion mechanisms of LTRs between the two structures. In addition, a novel repetitive sequence PCR630 was identified in the pericentromeres of B. rapa. Overall, the near-complete genome assembly, B. rapa Chiifu v4.0, offers valuable tools for genomic and genetic studies of Brassica species and provides new insights into the evolution of centromeres.

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