The effect of over-expression of rate limiting enzymes on the yield of artemisinin in Artemisia annua

Medicinal plants are rich source of bioactive compounds which are important for human healthcare. The production of bioactive compounds such as artemisinin is limited in plants. Novel antimalarial drug artemisinin was obtained from leaves of Artemisia annua L. plants. The content of artemisinin in the natural plant is 0.01-1.1 % on dry weight basis. Due to its low content, the drug could not be commercialized in the global market to explore the artemisinin-based combined therapies in the world. The economic limitations of chemical synthesis is unfeasible due to its complexity and cost effectiveness. In this article, we have studied the effect of rate limiting enzymes/genes expression, HMG-Co A reductase and amorpha-4,11-diene synthase on physiochemical changes in terms of total biomass, chlorophyll, total protein, artemisinin content and yield in transgenic lines of A. annua L. plants. The shoot length (42.00 %), number of leaves (86.89 %), the number of root (39.82 %) root length (83.61 %), total biomass accumulation (100 %), total chlorophyll level (138.14 %), total protein level (73.36 %) in TR4 at in vitro level while artemisinin (93.54 %) and its yield (237.26 %) were maximum in TR5 at polyhouse conditions, followed by TR1, TR2, TR3, TR7 and TR9 as compared to non-transgenic Artemisia annua L. plants. A similar trend in leaf biomass, stem biomass and leaf:stem ratio was also recorded in polyhouse condition.