Cloning and bioinformatics analysis of geranylgeranyl diphosphate synthase gene of Tripterygium wilfordii Clone and Expression Analysis of GGPPS1 Gene from Rehmannia glutinosa Cloning and expression analysis of GGPPS gene from Panax notoginseng Prokaryotic Expreesion and RNA Interference Vector Construction for Geranyl Diphosphate Synthase of Mentha haplocalyx Briq. Cloning and Expression Analysis of the SmGGPPS3 Gene from Salvia miltiorrhiza Cloning, sequence analysis, and prokaryotic expression of GrGPPS gene in Gentiana rigescens