[Cloning and induced expression analysis of 4-hydroxy-3-methyl-but-2-enyl diphosphate reductase gene (smHDR) of Salvia miltiorrhiza].

This study reported the obtainment of the full-length cDNA of Salvia miltiorrhiza hairy roots (Abbr: SmHDR, GenBank number: JX233817), via extracting Salvia miltiorrhiza hairy roots total RNA, designing specific primers according to the transcriptome data and using the RACE strategy, and then analyzed it with bioinformatics approaches. On this basis, using the real-time PCR to detect SmHDR gene expression after Ag+ induction, and testing tanshinones contents of corresponding samples by UPLC. SmHDR has 1 647 nucleotides, and an open reading frame (ORF) encoding a protein of 463 amino acid residues. The deduced protein has isoelectric point (pI) of 5.72 and a calculated molecular weight about 51.88 kD. In the secondary structure, the percentage of alpha helix, beta turn and random coil were 35.64%, 20.30% and 44.06%, respectively. Sequence alignment and phylogenetic analysis demonstrated that SmHDR had relative close relationship to the HDR of Picrorhiza kurrooa, similar to HDR from other species of plants. Real time PCR results indicated that elicitor of Ag+ stimulated the increase of mRNA expression of SmHDR. At the same time, results of ultra performance liquid chromatography (UPLC), used to examine the accumulation of diterpenoid tanshinones in hairy roots, showed that the contents of diterpenoid tanshinones in hairy roots of Salvia miltiorrhiza were increased dramatically at 12 h after treated with Ag+, and then decreased significantly. This result showed a positive correlation between the levels of mRNA expression and tanshinones accumulation in Salvia miltiorrhiza stimulated by Ag+. The content of tanshinones was gradually raised, and it had an obvious increase at 120 h. The bioinformatics analysis and gene expression indicated that SmHDR might be involved in tanshinones biosynthesis, which laid the foundation for further study of secondary metabolic regulation mechanism of tanshinones.