Evaluation of different levels of arsenic and phosphorus on antioxidant compounds content in Isatis cappadocica

Metalloid arsenic is considered as one of the most important environmental contaminant compounds. Some plants with high concentrations of arsenic accumulation in their shoots، have the ability to purify arsenic-contaminated areas. Due to the chemical similarity between arsenic and phosphate، similar behavior has been observed by plant uptake system. In this study، hydroponic experiment was conducted on Isatis cappadocica، as a newly-discovered hyperaccumulator. Accordingly، we conducted this experiment to compare the interaction of arsenic and phosphorus on antioxidant compounds of I. cappadocica. Therefore، the plants were grown for 6 weeks in a medium، embedded with combinations of 50، 200، 800 and 1200 μmol arsenic and 5، 50، 200، 800 and 1600 μmol phosphorus، respectively. The dry weight، hydrogen peroxide، antioxidant compounds and the arsenic and phosphorus concentration of harvestable parts were determined. The highest concentration of arsenic was obtained in plants treated with 1200 μmol As and 5 μmol phosphorus. Along with a marked increase in arsenic concentration in the media، a built up hydrogen peroxide was observed. Increasing arsenic concentration in the medium lead to increase of antioxidant compounds (carotenoids، anthocyanin and flavonoid). The accumulation of more than 700 mg kg-1 arsenic in the shoots، demonstrated the high resistance of I. cappadocica to arsenic stress and the existence of efficient mechanisms for reduced oxidative stress.