Sabot François, Schulman Alan H
MTT/BI Plant Genomics Laboratory, Institute of Biotechnology, Viikki Biocenter, University of Helsinki, Helsinki, Finland.
BMC Genomics. 2007 Jul 24;8:247. doi: 10.1186/1471-2164-8-247.
The LTR (long terminal repeat) retrotransposons of higher plants are replicated by a mutagenic life cycle containing transcription and reverse transcription steps. The DNA copies are often subject to recombination once integrated into the genome. Complex elements, where two elements share an LTR, are not uncommon. They are thought to result from heterologous recombination between two adjacent elements that occurs following their integration.
Here, we present evidence for another potential mechanism for the creation of complex elements, involving abnormal template switching during reverse transcription. The template switching creates a large, complex daughter element, formed by the fusion of two parent sequences, which is then inserted into the genome.
Those complex elements are part of the genome structure of plants in the Poaceae, especially in the Triticeae, but not of Arabidopsis. Hence, retrotransposon dynamics shaping the genome are lineage-specific.
高等植物的长末端重复（LTR）逆转座子通过包含转录和逆转录步骤的诱变生命周期进行复制。DNA拷贝一旦整合到基因组中，通常会发生重组。两个元件共享一个LTR的复合元件并不罕见。它们被认为是由两个相邻元件整合后发生的异源重组产生的。
在这里，我们提供了另一种产生复合元件的潜在机制的证据，该机制涉及逆转录过程中异常的模板转换。模板转换产生了一个由两个亲本序列融合形成的大的复合子元件，然后该子元件被插入到基因组中。
那些复合元件是禾本科植物，特别是小麦族植物基因组结构的一部分，但不是拟南芥基因组结构的一部分。因此，塑造基因组的逆转座子动态是谱系特异性的。
