• Transposable elements (TEs) are the main reason for the high plasticity of plant genomes, where they occur as communities of diverse evolutionary lineages. Because research has typically focused on single abundant families or summarized TEs at a coarse taxonomic level, our knowledge about how these lineages differ in their effects on genome evolution is still rudimentary.
• Here we investigate the community composition and dynamics of 32 long terminal repeat retrotransposon (LTR‐RT) families in the 272‐Mb genome of the Mediterranean grass Brachypodium distachyon.
• We find that much of the recent transpositional activity in the B. distachyon genome is due to centromeric Gypsy families and Copia elements belonging to the Angela lineage. With a half‐life as low as 66 kyr, the latter are the most dynamic part of the genome and an important source of within‐species polymorphisms. Second, GC‐rich Gypsy elements of the Retand lineage are the most abundant TEs in the genome. Their presence explains > 20% of the genome‐wide variation in GC content and is associated with higher methylation levels.
• Our study shows how individual TE lineages change the genetic and epigenetic constitution of the host beyond simple changes in genome size.

中文翻译：

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模型草二穗短柄草中长末端重复反转录转座子的多样性、动态和效应。

• 
  转座元件（TE）是植物基因组具有高可塑性的主要原因，它们作为不同进化谱系的群落出现。由于研究通常集中在单个丰富的家族或在粗略的分类水平上总结 TE，因此我们对这些谱系对基因组进化的影响如何不同的了解仍然很初级。
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  在这里，我们研究了地中海草Brachypodium distachyon 272 Mb 基因组中 32 个长末端重复逆转录转座子 (LTR-RT) 家族的群落组成和动态。
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  我们发现B. distachyon基因组中最近的转座活动大部分归因于着丝粒Gypsy家族和属于 Angela 谱系的Copia元件。后者的半衰期低至 66 kyr，是基因组中最具活力的部分，也是种内多态性的重要来源。其次，Retand 谱系中富含 GC 的吉普赛元素是基因组中最丰富的 TE。它们的存在解释了 20% 以上的 GC 含量全基因组变异，并且与较高的甲基化水平相关。
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  我们的研究展示了个体 TE 谱系如何改变宿主的遗传和表观遗传构成，而不仅仅是基因组大小的简单变化。