ABSTRACT
HMGR and DXR are key enzymes of terpenoids biosynthesis pathway. This study was aimed to discuss the effects of overexpression of HMGR and DXR from A momum villosum Lour. on the biosynthesis of terpenoids in transgenic tobacco. The real-time fluorescence quantitative PCR (RT-qPCR) was used to analyze the expression level of AvHMGR and AvDXR. Then, enzyme activities of HMGR and DXR were determined by spectrometer using the substrate-specific method. Different terpenoids were detected by GC-MS. The results showed that individual overex-pression of HMGR/DXR can inhibit the enzyme activities of HMGR and DXR but promote the biosynthesis of men-thene, neophytediene, cembrenene and sterol. The co-overexpression of HMGR and DXR had different enzyme activ-ities and can promote the biosynthesis of sterol and phytol, but inhibit the biosynthesis of neophytadiene. It was con-cluded that the overexpression of HMGR and DXR had diverse effects when regulating the biosynthesis of different terpenoids. This study provided the basis for using A vHMGR and A vDXR to regulate the metabolism of terpenoids.