Effects of exogenous methyl jasmonate and 2-isopentenyladenine on artemisinin production and gene expression in Artemisia annua

Artemisinin, produced in very low amounts in Artemisia annua L. plants, is one of the most effective drugs in treating malaria. In this study, the effect of exogenous applications of methyl jasmonate (MeJA) and 2-isopentenyladenine (2-iP) in artemisinin production and the main genes of its biosynthesis pathway within a 1-week time period were investigated. Both MeJA and 2-iP increased artemisinin content, but no correlation was found between gene expression and its content. In plants treated with 2-iP, despite increased gene expression following elicitor application, downregulation of gene expression was also observed, which might be attributed to the negative effects of rising artemisinin levels in gene expression. In plants treated with MeJA, the steady increase in artemisinin content was not explained by the few changes observed in gene expression, suggesting that some other mechanism may increase artemisinin. Our results indicate that the negative feedback mechanism of artemisinin is likely an obstacle for the selection of biotechnological strategies to increase artemisinin content. This may be overcome by studying the role of trichome in artemisinin production as a step toward achieving high yields of this valuable component.