Analysis of the plant retrotransposon Tto1 and its use for genetic manipulation

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Retroelements are pieces of DMA that can multiply more often than the host genome. To that end, the element-encoded enzyme reverse transcriptase uses retroelement RNA as a template to generate a DNA copy, which is inserted into the genome by another element-encoded protein, integrase. This process of retrotransposition is usually restricted to stressful conditions. Retroelements can make up more than half of the DNA content of animal and plant cells, but most of these elements are nonfunctional due to point mutations, deletions or insertions. We use biochemical and genetic methods to analyze a transpositioncompetent plant retrotransposon, Tto1. Our previous studies showed that current (textbook) knowledge of retroelement multiplication is surprisingly inadequate to understand transposition of Tto1. In addition to a more profound understanding of the retrotransposition process, our studies are directed towards application of this knowledge. Controlled (inducible) transposition in absence of the natural inducer, tissue culture stress, would turn Tto1 into a powerful tool for insertional mutagenesis, because Tto1 inserts preferentially into coding regions. Such a system would be particularly useful for plants with large genomes, where techniques such as positional cloning are not established or are too cumbersome.