on and on什么意思_Construction,of,cDNA,Phage,Expression,Library,of,Panax,Ginseng,Root,and,Differential,Expression,Analysis,of,cDNA,of,Dammarenediol,Synthase

　　（College of life science, Jilin Agriculture University, Changchun 130118,China）　　Abstract: Dammarenediol Synthase is the first key enzyme for ginsenoside biosynthesis, in Panax ginseng. In this study, cDNA cloning of DS was obtained from cDNA Phage Expression Library of P. ginseng root, and to detect expression level of DS gene in different years of panax ginseng roots. We constructed a cDNA phage expression library of five-year panax ginseng roots by SMART technique. 90 clones are randomly selected from the growth colony, and the bacterium solution is PCR identified. Then the recombinants are sequenced, followed by BLAST consistency search comparative analysis. The recombinant rate and titer of the library are computed. A relative fluorescent quantitative PCR method is adopted to detect the transcription expression level of mRNA of DS gene in panax ginsengs root of varying years. Results showed a cDNA phage expression library of five-year panax ginsengs is successfully constructed, with an recombinant rate of 95.17% and a titer of 8.38×106pfu. BLAST comparison analysis has found one recombinant fragment containing a conservative sequence of DS, which is a partial cDNA sequence of Dammarenediol Synthase. The fragment is 1473bp in size and it sequentially codes 491 amino acid residues. Relative fluorescent quantitative PCR analysis displayed that DS cDNA was distinctly up-regulated in root tissues of different years of panax ginsengs.
　　Key words: panax ginseng, phage, cDNA library, Dammarenediol Synthase , differential expression analysis