阳春砂和在烟草中单独及共同过量表达调控萜类化合物的生物合成

摘要

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.%目的：HMGR 和DXR 分别是萜类生物合成途径---MVA和MEP途径的关键酶，本研究探讨阳春砂A vHMGR 和A vDXR 在转基因烟草中的过量表达对不同萜类化合物生物合成的影响。方法：采用实时荧光定量 PCR（RT-qPCR）技术分析A vHMGR 和 A vDXR 的表达水平，应用专一底物法测定 HMGR 和DXR 的酶活性，利用气相色谱-质谱（GC-MS）联用技术检测不同萜类化合物的变化。结果：A vHMGR 或A vDXR 单独过量表达抑制了HMGR 和DXR 的活性，提高了五针松烯、新植二烯、薄荷烯和甾醇的含量；而A vHMGR 和A vDXR 共同过量表达对不同植株中酶活性的影响有差异，提高了甾醇和植醇的含量，但抑制了新植二烯的积累。结论：A vHMGR 和A vDXR 单独或共同过量表达对烟草中不同萜类化合物的合成调控存在差异，同时也证明了MVA和MEP途径并不完全独立，而是有着相互交流，本研究为利用阳春砂A vHMGR 和A vDXR 进行萜类化合物的代谢调控提供了依据。