[Identification and expression pattern analysis of a Moso Bamboo LTR retrotransposon]

To develop more active LTR retrotransposons in Phyllostachys edulis, a Ph. edulis LTR retrotransposon (Ph-LTR2) was identified, and the expression pattern of the transposon under stress was systematically analyzed. Ph-LTR2 transposon is 6 030 bp in length and belongs to the Reina subfamily in the Ty3-Gypsy family. With the similarity of 96.41% of both LTR sequences, the Ph-LTR2 transposon inserted the moso bamboo genome about 61.92 thousand years ago. There are 5 copies identified in the genome. The Ph-LTR2 transposon domain includes GAG (gag protein) protein domain, PR (Proteases) protein domain, RT (Reverse transcriptase) protein domain, RH (Ribonuclease H) protein domain, INT (Integrase) protein domain and CHR (Chromatin organization modifier) protein domain. The expression patterns of INT, RT and RH were detected by real-time quantitative PCR. The three domains were found to have specific expression patterns at different tissues of the bamboo. Under the conditions of low/high temperature, methylation inhibitors treatments, irradiation and high salt stress, transcription levels of the three domains of the Ph-LTR2 transposon increased with different degrees. Specifically, after treatment with low/high temperature and methylation inhibitors, the transcription level was up-regulated; after low dose radiation treatment and low concentration of salt solution treatment, the transcription level was also increased, but the expression level decreased with increasing dose of radiation and concentration of salt solution. These results indicate that the expression pattern of the Ph-LTR2 transposon responds to the changes of the external environment, but the exact mechanism is not yet known. The results of this study laid a certain theoretical foundation for the development of the genetic tool based on Ph-LTR2 transposons.