Arsenic-induced changes in morphological, physiological, and biochemical attributes and artemisinin biosynthesis in Artemisia annua, an antimalarial plant.

Present study is the first to explore physiological, biochemical and molecular changes in the medicinal plant Artemisia annua under arsenic (As) stress. A. annua grown hydroponically in a nutrient solution was spiked with increasing doses of As (0, 1,500, 3,000 and 4,500 μg l(-1)) for 7 days. Plants accumulated As in a dose dependent manner with bioconcentration factor 13.4 and translocation factor 0.97. While a similar trend of As accumulation was observed under soil culture experiments, the transfer factor went up to 2.1, depicting high efficiency of As translocation from roots to shoots by A. annua. Plants raised in 0-3,000 μg l(-1) As containing nutrient solution registered increase in root length, biomass, and carotenoid contents without any visual toxicity symptoms. A dose dependent increase in the activities of enzymes such as superoxide dismutase, ascorbate peroxidase, glutathione reductase and guaiacol peroxidase followed by a gradual decline at higher concentrations suggested their role in alleviating oxidative stress. Significant increase in the levels of thiols, GSH, and pcs gene transcript up to 3,000 μg l(-1) As attested their roles in As detoxification. Enhanced artemisinin production (an antimalarial compound) under As stress and upregulation of the transcripts (measured by RT-PCR) of the genes HMGR, FDS, ADS, and CYP71AV1 involved in artemisinin biosynthesis reaffirmed induction of artemisinin biosynthesis in A. annua under As stress. The results of the present study vividly suggested that A. annua has considerable As tolerance, and thus can be successfully cultivated in As contaminated fields.