Roulin Anne, Piegu Benoit, Fortune Philippe M, Sabot François, D'Hont Angélique, Manicacci Domenica, Panaud Olivier
Laboratoire Génome et Développement des Plantes, UMR CNRS/IRD/UPVD, Université de Perpignan, 52, avenue Paul Alduy, 66860 Perpignan, cedex, France.
BMC Evol Biol. 2009 Mar 16;9:58. doi: 10.1186/1471-2148-9-58.
Horizontal transfers (HTs) refer to the transmission of genetic material between phylogenetically distant species. Although most of the cases of HTs described so far concern genes, there is increasing evidence that some involve transposable elements (TEs) in Eukaryotes. The availability of the full genome sequence of two cereal species, (i.e. rice and Sorghum), as well as the partial genome sequence of maize, provides the opportunity to carry out genome-wide searches for TE-HTs in Poaceae.
We have identified an LTR-retrotransposon, that we named Route66, with more than 95% sequence identity between rice and Sorghum. Using a combination of in silico and molecular approaches, we are able to present a substantial phylogenetic evidence that Route66 has been transferred horizontally between Panicoideae and several species of the genus Oryza. In addition, we show that it has remained active after these transfers.
This study constitutes a new case of HTs for an LTR-retrotransposon and we strongly believe that this mechanism could play a major role in the life cycle of transposable elements. We therefore propose to integrate classe I elements into the previous model of transposable element evolution through horizontal transfers.
水平转移（HTs）是指在系统发育上距离较远的物种之间遗传物质的传递。尽管迄今为止描述的大多数水平转移案例都涉及基因，但越来越多的证据表明，在真核生物中有些水平转移涉及转座元件（TEs）。两种禾本科作物（即水稻和高粱）全基因组序列以及玉米部分基因组序列的可得性，为在禾本科中进行全基因组范围内的转座元件水平转移（TE-HTs）搜索提供了机会。
我们鉴定出一个长末端重复序列反转录转座子，命名为Route66，它在水稻和高粱之间具有超过95%的序列同一性。通过结合计算机模拟和分子方法，我们能够提供大量系统发育证据，证明Route66已在黍亚科和稻属的几个物种之间进行了水平转移。此外，我们表明它在这些转移之后仍然具有活性。
本研究构成了长末端重复序列反转录转座子水平转移的一个新案例，我们坚信这种机制可能在转座元件的生命周期中发挥重要作用。因此，我们建议通过水平转移将第一类元件整合到先前的转座元件进化模型中。
