Cloning and expression analysis of geraniol synthase gene in Gentiana rigescens

GrGES（ geraniol synthase） gene was cloned and its expression characters were examined in Gentiana rigescens，which would lay foundations for studies of function of this gene in geraniol and gentiopicroside biosynthesis. GrGES was cloned from leaves of G. rigescens by RT-PCR according to the GrGES sequence of transcriptome of G. rigescens. As a result，GrGES with its GenBank accession number KJ917168 was obtained. Sequence analysis showed that GrGES gene had a length of 1 767 bp coding for 588 amino acids. Its relative molecular weight was 67.84 ku with the theoretical isoelectric point of 5.56. GrGES may localize in chloroplast，and it was a hydropholic unstable protein composed of mainly α-helix（ 62.41%） and loop（ 39.57%）. The active sites in other GESs， N-terminal domain of terpene synthase（ IPR001906，81-273），domain of terpene synthas（ IPR005630， 263-588） were all existed in GrGES. GrGES protein was close to CrGES in Catharanthus roseus. The results of prokaryotic expression of GrGES gene in E. coli indicated that the recombinant protein was approximately 78.22 ku，which was consistent with the presumptive size. The tissue-specific expression results showed that GrGES gene was mainly expressed in leaf.