ABSTRACT
Objective To clone and analyze 3-hydroxy-3-methylglutaryl coenzyme-A synthase (HMGS) and 3-hydroxy-3-methylglutaryl coenzyme-A reductase (HMGR) genes from Panax notoginseng of four-year old during the flowering period, the key genes involved in the mevalonic acid pathway for saponin biosynthesis. Methods The cDNA sequences of PnHMGS1 and PnHMGR2 were obtained by reverse transcription PCR (RT-PCR) and rapid amplification of cDNA ends (RACE) methods and were analyzed in their secondary structures, subcellular localizations, domains, and the three-dimensional structures of putative proteins by the bioinformatics tools. Fusion genes were constructed by the prokaryotic expression system. Results The two genes were cloned, named as PnHMGS1 and PnHMGR2, respectively, and were both predicted to be located in the chloroplast. PnHMGS1 (1410 bp) encoded a predictive unstable protein with 469 amino acids and covered hydroxymethylglutaryl-CoA synthase domain. PnHMGR2 (1690 bp) also encoded an unstable protein with 589 amino acids and possessed a hydroxymethylglutaryl-coenzyme A reductase domain and two transmembrane regions. Both of the genes were expressed most in flowers followed by roots, stems, and least in leaves. Conclusion PnHMGS1 and PnHMGR2 are firstly cloned from P. notoginseng as the new member of the HMGR family, and they show the same expression profile as P. ginseng and P. quinquefolius.