Impact of Low-Energy Ion Beam Implantation on the Expression of Ty1-copia-like Retrotransposons in Wheat (Triticum aestivum)

Retrotransposon-like elements are major constituents of most eukaryotic genomes. For example, they account for roughly 90% of the wheat (Triticum aestivum) genome. Previous study on a wheat strain treated by low-energy N+ ions indicated the variations in AFLP (Amplified Fragment Length Polymorphism ) markers. One such variation was caused by the re-activation of Ty1-copia-like retrotransposons, implying that the mutagenic effects of low-energy ions might work through elevated activation of retrotransposons. In this paper an expression profile of Ty1-copia-like retrotransposons in wheat treated by low-energy N+ ions is reported. The reverse transcriptase (RT) domains of these retrotransposons were amplified by reverse-transcriptional polymerase chain reaction (RT-PCR) and sequentially cloned. 42 and 65 clones were obtained from the treated (CL) and control materials (CK), respectively. Sequence analysis of each clone was performed by software. Phylogeny and classification were calculated responding to the sequences of the RT domains. All the results show that there is much difference in the RT domain between the control sample and the treated sample. Especially, the RT domains from the treated group encode significantly more functional ORF (open reading frames) than those from the control sample. This observation suggests that the treated sample has higher activation of retrotransposons, possibly as a consequence of low-energy ion beam irradiation. It also suggests that retrotransposons in the two groups impact the host gene expression in two different ways and carry out different functions in wheat cells