Retrotransposon-like elements are major constituents of most eukaryotic genomes.For example,they account for roughly 90% of the wheat (Triticum aestivum) genome.Previ-ous 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 bythe re-activation of Tyl-copia-like retrotransposons,implying that the mutagenic effects of low-energy ions might work through elevated activation of retrotransposons.In this paper an ex-pression profile of Tyl-copia-like retrotransposons in wheat treated by low-energy N+ ions isreported.The reverse transcriptase (RT) domains of these retrotransposons were amplified byreverse-transcriptional polymerase chain reaction (RT-PCR) and sequentially cloned.42 and 65clones were obtained from the treated (CL) and control materials (CK),respectively.Sequenceanalysis of each clone was performed by software.Phylogeny and classification were calculatedresponding to the sequences of the RT domains.All the results show that there is much differencein the RT domain between the control sample and the treated sample.Especially,the RT domainsfrom the treated group encode significantly more functional ORF (open reading frames) than thosefrom the control sample.This observation suggests that the treated sample has higher activationof retrotransposons,possibly as a consequence of low-energy ion beam irradiation.It also suggeststhat retrotransposons in the two groups impact the host gene expression in two different ways andcarry out different functions in wheat cells.
