Artemisinin, an effective drug against Plasmodium species that cause malaria, is a sesquiterpene lactone isolated from Artemisia annua. The yield of artemisinin in plants is relatively low, and it is influenced by various environmental growing conditions. In Arabidopsis, cryptochrome 1 (CRY1) is one of the key receptors that perceive light signals, and its overexpression promotes accumulation of secondary metabolites. In this study, overexpression of Arabidopsis CRY1 in A. annua resulted in increased accumulation of both artemisinin and anthocyanins. Under blue light, transgenic plants expressing high level of AtCRY1 showed a variety of blue light-induced responses, including inhibition of hypocotyl elongation and cotyledon expansion, dwarfism, and purpuring of aerial organs. Reverse transcription polymerase chain reaction analysis revealed that expression levels of the phenylalanine ammonia-lyase- and chalcone synthase-encoding genes were elevated and that anthocyanin accumulation was increased. Expression analysis of genes encoding farnesyl diphosphate synthase (FPS), amorpha-4,11-diene synthase (ADS), and CYP71AV1, three important enzymes in artemisinin biosynthesis, indicated that transcript abundance of all three genes, FPS, ADS, and CYP71AV1, increased in AtCRY1 plants. Based on high performance liquid chromatography analysis, artemisinin content in these plants increased by 30 similar to 40%, when compared to control. These results have demonstrated that alteration of light signaling components could provide a viable approach for enhancing production of the secondary metabolite artemisinin.
