Centromeric DNA characterization in the model grass Brachypodium distachyon provides insights on the evolution of the genus
Centromeric DNA characterization in the model grass Brachypodium distachyon provides insights on the evolution of the genus
复制标题
模型草 Brachypodium distachyon 的着丝粒 DNA 表征为该属的进化提供了见解。
DOI：
10.1111/tpj.13832
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发表时间：
2018-03-01
期刊：
影响因子：
7.2
通讯作者：
Wang, Kai
中科院分区：
文献类型：
--
作者：
Li, Yinjia;Zuo, Sheng;Wang, Kai
二穗短柄草（Brachypodium distachyon）是一种成熟的模式单子叶植物，其小而紧凑的基因组已被用作谷类植物（如燕麦（Avena sativa）（燕麦）、大麦（Hordeum vulgare）（大麦）和小麦（Triticum aestivum）（小麦））的大得多且通常为多倍体的基因组的准确参考。着丝粒是染色体中不可缺少的功能单位，在进化过程中的基因组多倍化事件中起着核心作用。由于短柄草属约有20个种，它们在基本染色体数目、基因组大小、倍性水平和生活策略方面存在显著差异，因此研究它们的着丝粒可能为了解这一有趣而重要的属的基因组结构和进化提供重要的见解。在这项研究中，我们分离的着丝粒DNA的B。二穗草参考线Bd 21，并通过含有着丝粒特异性组蛋白CENH 3的核小体的染色质免疫沉淀来表征其组成。结果表明，Bd 21的着丝粒具有典型的多细胞真核着丝粒的特征。引人注目的是，这些着丝粒含有相对较少的着丝粒卫星DNA;特别是，第5号染色体（Bd 5）的着丝粒仅由近似40 kb的DNA组成。此外，在B中，着丝粒反转录转座子。二穗子（CRBds）在进化上是年轻的。这些转座因子位于CENH 3结合结构域内和邻近CENH 3结合结构域，并且具有相似的组成。此外，基于着丝粒中CRBds的存在，本研究中的物种可以分为两个不同的谱系。这可能为短柄草属内的系统发育关系提供新的证据。
Brachypodium distachyon is a well-established model monocot plant, and its small and compact genome has been used as an accurate reference for the much larger and often polyploid genomes of cereals such as Avena sativa (oats), Hordeum vulgare (barley) and Triticum aestivum (wheat). Centromeres are indispensable functional units of chromosomes and they play a core role in genome polyploidization events during evolution. As the Brachypodium genus contains about 20 species that differ significantly in terms of their basic chromosome numbers, genome size, ploidy levels and life strategies, studying their centromeres may provide important insight into the structure and evolution of the genome in this interesting and important genus. In this study, we isolated the centromeric DNA of the B. distachyon reference line Bd21 and characterized its composition via the chromatin immunoprecipitation of the nucleosomes that contain the centromere-specific histone CENH3. We revealed that the centromeres of Bd21 have the features of typical multicellular eukaryotic centromeres. Strikingly, these centromeres contain relatively few centromeric satellite DNAs; in particular, the centromere of chromosome 5 (Bd5) consists of only similar to 40kb. Moreover, the centromeric retrotransposons in B. distachyon (CRBds) are evolutionarily young. These transposable elements are located both within and adjacent to the CENH3 binding domains, and have similar compositions. Moreover, based on the presence of CRBds in the centromeres, the species in this study can be grouped into two distinct lineages. This may provide new evidence regarding the phylogenetic relationships within the Brachypodium genus.