Template switching can create complex LTR retrotransposon insertions in Triticeae genomes
1 MTT/BI Plant Genomics Laboratory, Institute of Biotechnology, Viikki Biocenter, University of Helsinki, P.O. Box 56, FIN-00014 University of Helsinki, Finland
2 Plant Genomics, Biotechnology and Food Research, MTT Agrifood Research Finland, Myllytie 10, FIN-31600 Jokioinen, Finland
BMC Genomics 2007, 8:247 doi:10.1186/1471-2164-8-247Published: 24 July 2007
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.