Based on the transcriptome of Gentiana rigescens,a gene designated as GrSLS1(GenBank NO.KF941191) encoding secologanin synthase was cloned from young leaves of G.rigescens by RT-PCR technology.The sequence analysis results showed that the open reading frame of GrSLS1 gene has a length of 1 560 bp coding for 519 amino acids,and the relative molecular weight of GrSLS1 protein is 59.33 kD with its pI of 8.96.Bioinformatics analysis indicated that GrSLS1 protein belongs to the member of SLS family,and it has a transmembrane helix(10—32) in the N terminal.Results of secondary structure analysis suggested that GrSLS1 protein composes of mainly α-helix and irregular coils.Results of phylogenic analysis showed that GrSLS1 protein is close to MsSLS2 of Mitragyna speciosa.The prokaryotic expression of GrSLS1 gene was done after construction of its prokaryotic expression vector pGEX-4T-GrSLS1,and the SDS-PAGE results displayed that the expressed protein was consistent with the anticipated size.This study will lay a foundation for further functional research of GrSLS1 gene and the improvement of gentiopicroside content via overexpression of this gene in gentian.