Engelhardt Institute of Molecular Biology, Russian Academy of Sciences, Moscow, Russia.
Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, Moscow, Russia.
BMC Evol Biol. 2019 Feb 26;19(Suppl 1):49. doi: 10.1186/s12862-019-1375-6.
Members of different sections of the genus Linum are characterized by wide variability in size, morphology and number of chromosomes in karyotypes. Since such variability is determined mainly by the amount and composition of repeated sequences, we conducted a comparative study of the repeatomes of species from four sections forming a clade of blue-flowered flax. Based on the results of high-throughput genome sequencing performed in this study as well as available WGS data, bioinformatic analyses of repeated sequences from 12 flax samples were carried out using a graph-based clustering method.
It was found that the genomes of closely related species, which have a similar karyotype structure, are also similar in the repeatome composition. In contrast, the repeatomes of karyologically distinct species differed significantly, and no similar tandem-organized repeats have been identified in their genomes. At the same time, many common mobile element families have been identified in genomes of all species, among them, Athila Ty3/gypsy LTR retrotransposon was the most abundant. The 30-chromosome members of the sect. Linum (including the cultivated species L. usitatissimum) differed significantly from other studied species by a great number of satellite DNA families as well as their relative content in genomes.
The evolution of studied flax species was accompanied by waves of amplification of satellite DNAs and LTR retrotransposons. The observed inverse correlation between the total contents of dispersed repeats and satellite DNAs allowed to suggest a relationship between both classes of repeating sequences. Significant interspecific differences in satellite DNA sets indicated a high rate of evolution of this genomic fraction. The phylogenetic relationships between the investigated flax species, obtained by comparison of the repeatomes, agreed with the results of previous molecular phylogenetic studies.
不同亚麻属节的成员在大小、形态和染色体组型的染色体数目方面具有广泛的可变性。由于这种可变性主要由重复序列的数量和组成决定，因此我们对形成蓝色亚麻聚类的四个节的物种的重复组进行了比较研究。基于本研究中进行的高通量基因组测序的结果以及可用的 WGS 数据，使用基于图的聚类方法对来自 12 个亚麻样本的重复序列进行了生物信息学分析。
发现具有相似核型结构的密切相关的物种的基因组在重复组组成上也相似。相比之下，染色体上明显不同的物种的重复组差异很大，并且在它们的基因组中没有鉴定出类似的串联组织的重复。同时，在所有物种的基因组中都鉴定出了许多常见的移动元件家族，其中 Athila Ty3/gypsy LTR 反转录转座子最为丰富。属 Linum 节的 30 条染色体成员（包括栽培种亚麻 L. usitatissimum）与其他研究物种的差异很大，其基因组中卫星 DNA 家族的数量及其相对含量都很大。
研究中亚麻物种的进化伴随着卫星 DNA 和 LTR 反转录转座子的扩增浪潮。观察到分散重复序列的总含量与卫星 DNA 之间的负相关关系，表明这两类重复序列之间存在关系。卫星 DNA 组的显著种间差异表明该基因组部分的进化速度很高。通过比较重复组获得的调查亚麻物种的系统发育关系与以前的分子系统发育研究结果一致。
