Overexpression of Allene Oxide Cyclase Improves the Biosynthesis of Artemisinin in Artemisia annua L.

Jasmonates (JAs) are important signaling molecules in plants and play crucial roles in stress responses, secondary metabolites' regulation, plant growth and development. In this study, the promoter of AaAOC, which was the key gene of jasmonate biosynthetic pathway, had been cloned. GUS staining showed that AaAOC was expressed ubiquitiously in A. annua. AaAOC gene was overexpressed under control of 35S promoter. RT-Q-PCR showed that the expression levels of AaAOC were increased from 1.6- to 5.2-fold in AaAOC-overexpression transgenic A. annua. The results of GC-MS showed that the content of endogenous jasmonic acid (JA) was 2- to 4.7-fold of the control level in AaAOC-overexpression plants. HPLC showed that the contents of artemisinin, dihydroartemisinic acid and artemisinic acid were increased significantly in AaAOC-overexpression plants. RT-Q-PCR showed that the expression levels of FPS (farnesyl diphosphate synthase), CYP71AV1 (cytochrome P450 dependent hydroxylase) and DBR2 (double bond reductase 2) were increased significantly in AaAOC-overexpression plants. All data demonstrated that increased endogenous JA could significantly promote the biosynthesis of artemisinin in AaAOC-overexpression transgenic A.annua.