Whole genome surveys of rice, maize and sorghum reveal multiple horizontal transfers of the LTR-retrotransposon Route66 in Poaceae.
BACKGROUND
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.


RESULTS
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.


CONCLUSIONS
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.
Roulin
Anne
A
Laboratoire Génome et Développement des Plantes, UMR CNRS/IRD/UPVD, Université de Perpignan, 52, avenue Paul Alduy, 66860 Perpignan, cedex, France. anne.roulin@univ_perp.fr
Piegu
Benoit
B
Fortune
Philippe M
PM
Sabot
François
F
D'Hont
Angélique
A
Manicacci
Domenica
D
Panaud
Olivier
O
D019295:Computational Biology; D019143:Evolution, Molecular; D018506:Gene Expression Regulation, Plant; D022761:Gene Transfer, Horizontal; D017343:Genes, Plant; D018745:Genome, Plant; D012275:Oryza / Q000235:genetics*; D010802:Phylogeny; D018626:Retroelements; D016415:Sequence Alignment; D045868:Sorghum / Q000235:genetics*; D020079:Terminal Repeat Sequences; D003313:Zea mays / Q000235:genetics*
D018626:Retroelements