Growth, photosynthetic efficiency and metabolic alterations associated with exogenous hydrogen peroxide in Artemisia annua: Overproduction of artemisinin

Abstract

Artemisinin, a sesquiterpene lactone with a peroxide linkage, has been held responsible for antimalarial activity of the Artemisia annua L. Recently, it was reported that reactive oxygen species (ROS) play important role in the biosynthesis of artemisinin by catalyzing some important intermediate steps. The effect of exogenously supplied hydrogen peroxide (1.00 mM and 2.00 mM H2O2), in two ways, foliar and as soil drench, was worked out in terms of growth, alteration in photosynthesis, oxidative damage, antioxidant defense enzymes and artemisinin level in exposed plants. Application of H2O2 positively affect the growth of the treated plants; and increment in net photo synthetic rate, stomatal conductance, internal CO2 and chlorophyll content in the H2O2 exposed A. annua plants was noted. A significant upregulation in antioxidant enzymes viz. catalase (CAT), peroxidase (POX) and superoxide dismutase (SOD) was observed as a result of exogenous H2O2 treatment when applied foliarly or as soil drench. H2O2application either by 1.00 mM or 2.00 mM stimulated artemisinin levels, however, 2.00 mM H2O2 applied as soil drench elicited artemisinin production more rapidly compared to other treatments. Therefore, results suggest that exogenous H2O2 may stimulate growth by inducing antioxidant defense system and increase the artemisinin levels in Artemisia annua plants.