Chang Kai, Qiu Fei, Chen Min, Zeng Lingjiang, Liu Xiaoqiang, Yang Chunxian, Lan Xiaozhong, Wang Qiang, Liao Zhihua
Key Laboratory of Eco-environments in Three Gorges Reservoir Region (Ministry of Education), Chongqing Engineering and Technology Research Centre for Sweetpotato, School of Life Sciences, Southwest University, Chongqing, People's Republic of China; Chengdu Grain Storage Research Institute, State Administration of Grain Reserves, Chengdu, People's Republic of China.
Biotechnol Appl Biochem. 2014 May-Jun;61(3):249-55. doi: 10.1002/bab.1176. Epub 2014 Mar 18.
The 2-C-methyl-D-erythritol-4-phosphate (MEP) pathway genes encoding DXR and MECS from Taxus species and STR from Catharanthus roseus were used to genetically modify the ajmalicine biosynthetic pathway in hairy root cultures of C. roseus. As expected, the STR-overexpressed root cultures showed twofold higher accumulation of ajmalicine than the control. It was important to discover that overexpression of the single DXR or MECS gene from the MEP pathway also remarkably enhanced ajmalicine biosynthesis in transgenic hairy root cultures, and this suggested that engineering the MEP pathway by overexpression of DXR or MECS promoted the metabolic flux into ajmalicine biosynthesis. The transgenic hairy root cultures with co-overexpression of DXR and STR or MECS and STR had higher levels of ajmalicine than those with overexpression of a single gene alone such as DXR, MECS, and STR. It could be concluded that transgenic hairy root cultures harboring both DXR/MECS and STR possessed an increased flux in the terpenoid indole alkaloid biosynthetic pathway that enhanced ajmalicine yield, which was more efficient than cultures harboring only one of the three genes.
来自红豆杉属物种的编码1-脱氧-D-木酮糖-5-磷酸还原异构酶（DXR）和2-C-甲基-D-赤藓糖醇-2,4-环焦磷酸合酶（MECS）的2-C-甲基-D-赤藓糖醇-4-磷酸（MEP）途径基因以及来自长春花的异胡豆苷合成酶（STR）基因被用于对长春花毛状根培养物中的阿吗碱生物合成途径进行基因改造。正如预期的那样，过表达STR的根培养物中阿吗碱的积累量比对照高出两倍。重要的是发现，MEP途径中单个DXR或MECS基因的过表达也显著增强了转基因毛状根培养物中阿吗碱的生物合成，这表明通过过表达DXR或MECS对MEP途径进行工程改造促进了代谢流进入阿吗碱生物合成。同时过表达DXR和STR或MECS和STR的转基因毛状根培养物中的阿吗碱水平高于单独过表达单个基因（如DXR、MECS和STR）的培养物。可以得出结论，同时含有DXR/MECS和STR的转基因毛状根培养物在萜类吲哚生物碱生物合成途径中具有增加的通量，从而提高了阿吗碱产量，这比仅含有这三个基因之一的培养物更有效。
