Repetitive sequences are ubiquitous and fast-evolving elements responsible for size variation and large-scale organization of plant genomes. Within tribe Phaseoleae (Fabaceae), some genera, such as Phaseolus, Vigna, and Cajanus, show small genome and mostly stable chromosome number. Here, we applied a combined computational and cytological approach to study the organization and diversification of repetitive elements in some species of these genera. Sequences were classified in terms of type and repetitiveness and the most abundant were mapped to chromosomes. We identified long terminal repeat (LTR) retrotransposons, especially Ogre and Chromovirus elements, making up most of genomes, other than P. acutifolius and Vigna species. Satellite DNAs (SatDNAs) were less representative, but highly diverse among species, showing a clear phylogenetic relationship. In situ localization revealed preferential location at pericentromeres and centromeres for both types of sequences, suggesting a heterogeneous composition, especially for centromeres. Few elements showed subterminal accumulation. Copy number variation among chromosomes within and among species was observed for all nine identified SatDNAs. Altogether, our data pointed two main elements (Ty3/Gypsy retrotransponsons and SatDNAs) to the diversification on the repetitive landscape in Phaseoleae, with a typical set of repeats in each species. The high turnover of these sequences, however, did not affect total genome size.

中文翻译：

---

菜豆和相关属Cajanus L.和Vigna Savi紧密基因组内重复序列的多样性。

重复序列是普遍存在且快速发展的元件，其负责植物基因组的大小变化和大规模组织。在菜豆属（豆科）中，有些属，如菜豆，Vi豆和卡雅努斯，显示出小的基因组，且染色体数大多稳定。在这里，我们应用了一种计算和细胞学相结合的方法来研究这些属某些物种中重复元件的组织和多样化。根据类型和重复性对序列进行分类，最丰富的序列被定位到染色体上。我们确定了长末端重复（LTR）逆转录转座子，尤其是食人魔和染色体病毒元件，这些基因构成了除拟青霉和Vigna物种以外的大部分基因组。卫星DNA（SatDNA）代表性较低，但物种间差异很大，显示出明确的系统发育关系。原位定位揭示了两种类型序列在着丝粒和着丝粒处的优先定位，这表明异质组成，特别是着丝粒。几乎没有元素显示出亚末端积累。对于所有九种已鉴定的SatDNA，在物种内部和物种之间的染色体之间的拷贝数变化均得到观察。总之，我们的数据指出了两个主要元素（Ty3 /吉普赛逆转录应答子和SatDNA）指向菜豆科重复性景观的多样化，每个物种都有典型的重复序列。这些序列的高周转率，但是，不影响总基因组大小。几乎没有元素显示出亚末端积累。对于所有九种已鉴定的SatDNA，在物种内部和物种之间的染色体之间的拷贝数变化均得到观察。总之，我们的数据指出了两个主要元素（Ty3 /吉普赛逆转录应答子和SatDNA）指向菜豆科重复性景观的多样化，每个物种都有典型的重复序列。这些序列的高周转率，但是，不影响总基因组大小。几乎没有元素显示出亚末端积累。对于所有九种已鉴定的SatDNA，在物种内部和物种之间的染色体之间的拷贝数变化均得到观察。总之，我们的数据指出了两个主要元素（Ty3 /吉普赛逆转录应答子和SatDNA）指向菜豆科重复性景观的多样化，每个物种都有典型的重复序列。这些序列的高周转率，但是，不影响总基因组大小。