Metabolic adaptations to arsenic-induced oxidative stress in Isatis cappadocica. Naser Karimi* and Zahra Souri

Arsenic is considered as one of the most important environmental contaminant elements. Some plant species can grow in arsenic contaminated soils and they are able to reduce arsenic toxicity. In this study, a hydroponic experiment was conducted on Isatis cappadocica, a newly-discovered As hyperaccumulator. Accordingly, we conducted this experiment to compare the interaction of effect of arsenic and phosphorus on total chlorophyll and antioxidant compounds (carotenoids, anthocyanin and proline) of I. cappadocica for better understanding the mechanisms applied by this species. Therefore, the plants were grown for 6 weeks in a medium, embedded with combinations of 50, 200, 800 and 1200 μmol l−1 arsenic and 5, 50, 200, 800 and 1600 μmol l−1 phosphorus, respectively. The highest concentration of arsenic was obtained in plants treated with 1200 μmol l−1 As and 5 μmol l−1 phosphorus. Increasing arsenic concentration in the medium led to increase in antioxidant compounds. The ability of Isatis to accumulate more than 700 mg kg-1 arsenic in the shoots, illustrates the high resistance of this plant to arsenic and the existence of efficient mechanisms including increase of antioxidant compounds.