Transcriptome Of Dendrobium Officinale Under Cold Stress And Isolation And Expression Analysis Of Ty1-copio Group Retrotrarisposons

Dendrobium officinale Kimura et Migo is famous and rare traditional medicinal herbs andfrost is a bottleneck problem in the development of its industry. Therefore, transcriptome anddifferential gene expression patterns of D.offiecinale under cold stress using the second generationsequencing technology were studied in this study, and excavated cold resistance genes andexplored the relationship between Ty1-copia like retrotransposons and the defense mechanisms ofD.offiecinale. The results were showed as follows:The transcriptome of D.offiecinal C15from Zhejiang Lin’an which has strong cold resistancewere analyzed using the IlluminaHiSeq2000sequencing platform. Approximately77millionpaired-end reads were obtained. These reads were assembled into50,783Unigenes with anaverage length of838nt. Compared to the database, most cold resistance related genes areannotated from datebases. On the basis of transcriptome data, the C15were respectively cultivatedin different time at low temperature (4℃). The above samples were measured by Digital GeneExpression Profiling(DGE) and then analyzed gene expression pattern of D.offiecinale under coldstress.15cold resistance genes were filtered and a lot of stress-related transposons were found.Ty1-copia retrotransposon RT gene fragments were amplified PCR from genomic DNA ofC15and A39(Yunnan Guangnan) and their heterogeneity of RT sequences were analyzed. Theresults showed that these sequences contained many regulatory elements which related withdifferent stress conditions. All the sequences were translated into amino acids and then analyzedby phylogenic analysis, and the phylogenic tree showed they have high homology with otherplants (eg. Triticum aestivum, Eleocharis quinqueflora), which indicated that horizontaltransmission of retrotransposon occurred among the plants in the past.The transcriptional activity of Ty1-copia retrotransposon in D. officinale induced with100μmol·L-1exogenous abscisic acid (ABA) at different time. Ty1-copia like retrotransposon RTwith transcriptionally activatityand high heterogeneity were obtained． The difference withTy1-copia like retrotransposon RT of genome is that the regulatory elements induced by stressconditions of reverse transcriptase transcriptionally activated of Ty1-copia retrotransposons were significantly increased. Phylogenic analysis of their amino acid sequences found that they havelow homology with Ty1-copia like retrotransposon RT of genome.In order to study the relationship between the transcriptional activity of Ty1-copiaretrotransposon and defense mechanisms of D. officinale, Ty1-copia like retrotransposon RT wasamplified by RT-PCR from the C15induced under osmotic stress and cold stress. Analysis of allthe transcriptional activity sequences found that the regulatory elements induced by stressconditions were significantly increased. Phylogenic analysis of their amino acid sequences showedthat the sequences which respectively induced by cold stress and osmotic stress mixed togetherand they had obvious differences with Ty1-copia like retrotransposon RT of genome.