Comparative profiling and dynamics of artemisinin related metabolites using efficient protocol and expression of biosynthetic pathway genes during developmental span of two elite varieties of Artemisia annua L

Abstract

Artemisinin a natural sesquiterpenoid isolated from Artemisia annua, is of great interest in the treatment of malaria. In this study important artemisinin and related metabolites were profiled throughout the defined developmental period by utilizing efficient reversed-phase HPLC method with UV detection in two elite varieties CIM-Arogya and Jeevan raksha of Artemisa annua L. Further to gain insight in to the regulation of artemisinin biosynthesis and accumulation during plant ontogeny, expression profiling of eight genes of artemisinin biosynthetic pathway were performed in both the varieties. We found higher expression of all transcripts of artemisinin biosynthetic pathway during plant ontogeny. High level of up regulation of these genes during plant ontogeny was associated with higher level of secondary metabolite content. Relative dynamics of artemisinin metabolites followed an increasing pattern till the month of November. A. annua CIM-Arogya variety had higher accumulation mainly in upper leaves. Interestingly, dihydroartemisinic acid accumulation was at variance with that of artemisinin and arteannuin B, suggesting later months of development preferred equilibrium towards artemisinin accumulation mediated through uncharacterized catalytic transformation. This behavioural dynamics might have some eco-physiological role to play for the plant.