Isolation and characterization of a 3-hydroxy-3-methylglutaryl coenzyme A reductase 2 promoter from Salvia miltiorrhiza

The aim of the present study was to isolate and characterize the 5′ regulatory region of Salvia miltiorrhiza 3-hydroxy-3-methylglutaryl coenzyme A reductase 2 gene. The entire fragment is 2696 bp long and consists of the promoter, 5′UTR and 85 nucleotide 5′ fragments of the CDS region. The results of in silico bioinformatic tests indicate that the promoter region contains repetitions of many potential cis-active elements serving as the recognition sites for transcription factors. Data obtained from the in silico tests are verified by co-expression studies based on A. thaliana microarray data to make them more probably to occur. The bioinformatic analysis indicated no tandem repeats or CpNpG islands in the promoter. However, potential target sites for miRNA 156 and miRNA 159 were found in the 5′ UTR segment. In addition, two possible polymorphic sites, A2719G and A2744C, were found in the CDS region. Finally, the activity of isolated fragment was evaluated experimentally by quantitative RT–PCR. The promoter activity of the isolated 2696 bp HMGR2 gene fragment was confirmed by RT–PCR studies of in vitro cultured, transformed S. miltiorrhiza plants. Analysis of the RT–PCR results revealed temporal changes in the promoter activity occurring in response to treatment by five abiotic factors: auxin, gibberellin, salicylic acid, abscisic acid and 100 mM NaCl.