engleski

Expression of the tobacco retrotransposon Tto1 in the plant Arabidopsis thaliana L.

Retrotransposons are the commonest class of eukaryotic transposable elements and have recently been shown to occupy a large proportion (up to 12%) of all plant genomes. However, little can be said about their contribution (if any) to growth, development and biological fitness of the host organisms. An impediment to investigation of retrotransposons in native host is the considerable background of copies. To circumvent this problem we have tried to express tobacco retrotransposon Tto1 in the plant Arabidopsis thaliana. Heterologous expression of retrotransposons or reconstitution of individual steps of retrotransposon life cycle in heterologous hosts, might be a way to learn more about host-element interaction and might shed light on the interesting problem of horizontal transfer. It would be also very valuable to develop the system for gene tagging based on the retrotransposon particularly for the plant A. thaliana. In this study the roots of A. thaliana were transformed with Tto1 using agrobacterial system. In parallel with wild type, two derivates of Tto1 with mutations in integrase or protease domain have been tested. In order to asses the activity of Tto1 an intron was inserted into the integrase domain in both mutated constructs. In all calli lines derived from roots transformed with wild type Tto1, the homologous recombination between two long terminal repeats of the Tto1 copy in T-DNA has occured. The same has happened with the most protease minus derivates. The rest of the protease minus constructs did not show detectable activity of transposition. In contrary, no homologous recombination occured in integrase minus derivates and all of them underwent reverse transcription as PCR and Southern blot results showed. In this study Tto1 was able to complete its life cycle in heterologous host A. thaliana.

Arabidopsis thaliana L.; retrotransposons; gene expression

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