Strategies for enhancing artemisinin production in Artemisia annua under changing environment

Abstract

Artemisia annua L. (family Asteraceae), is the only source of a potent anti-malarial drug, artemisinin. Artemisinin, a sesquiterpene lactone containing an endoperoxide bridge, has been recognized as an effective and safe remedy against malaria parasite Plasmodium falciparum. However, the concentration of artemisinin in the plant is very low, ranging from 0.01 to 0.8%. Exposure of A. annua plants to abiotic stresses, such as of light, temperature, salinity, heavy metals and UV light, have been reported to enhance ROS generation, which augment artemisinin yield by facilitating rapid conversion of artemisinic acid to artemisinin. In fact, generation rate of H2O2 increased consistently under abiotic stress conditions, suggesting a direct relationship between generation of H2O2 and artemisinin biosynthesis in A. annua. Various scientific approaches have been attempted to increase artemisinin production including chemical synthesis and genetic engineering of the pathway genes involved in artemisinin biosynthesis in A. annua; but, not much success has been accomplished till now due to high cost of procedure or complex nature of regulation and expression of the genes responsible for artemisinin biosynthesis. Plant growth regulators (PGRs) exhibit a broad spectrum of physiological effects in plants which may influence the inter-relationships between primary and secondary metabolism leading to increased biosynthesis of secondary metabolites. As per our study, employing pot and field experiments, some PGRs (gibberellic acid, salicylic acid, methyl jasmonate etc.) and radiation-processed polysaccharides (sodium alginate and carrageenan) proved as non-conventional elicitors that enhanced the overall yield of artemisinin under normal and abiotic stress conditions. In order to increase the desired production of artemisinin and utilize the land unsuitable for food crops, cultivation of A. annua might be employed with new scientific approaches and convenient strategies.