Enhancement of artemisinin biosynthesis by overexpressing dxr, cyp71av1 and cpr in the plants of Artemisia annua L

Artemisinin is extracted from a traditional Chinese medicinal herb Artemisia annua L., which is regarded as the most efficient drug against malaria in the world. In recent years, attention has been paid to increase the artemisinin content through transgenic methods because of the low content of artemisinin in wild plants. In this article, three functional artemisinin-related genes namely dxr, cyp71av1 and cpr, were used to genetically modify the artemisinin biosynthesis pathway in A. annua. Four independent transgenic lines of A. annua plants with overexpression of dxr and five independent transgenic A. annua lines with overexpression of both cyp71av1 and cpr were obtained and confirmed through genomic PCR. All the transgenic A. annua plants with overexpression of the dxr gene showed higher levels of artemisinin than the wild type. The content of artemisinin in the Line D24 with overexpression of dxr (1.21±0.01 mg·g DW) was more than two times compared with that in the wild type (0.52±0.01 mg·g DW). All the five lines of co-overexpressing cyp71av1 and cpr had an increase of artemisinin production compared with the wild-type A. annua. Line No. 16 with overexpression of cyp71av1 and cpr had the highest content of artemisinin (2.44±0.13 mg·g DW) at nearly three times of the wild-type A. annua (0.91±0.02 mg·g DW). Thus, the present study demonstrated that genetic modification of the upstream 2-C-methyl-D-erythritol 4-phosphate pathway or metabolic engineering of the artemisinin-specific pathway could, respectively, enhance artemisinin biosynthesis. These strategies could be applied to develop transgenic A. annua with higher levels of artemisinin.