Arsenic stress response and detoxification mechanism in arsenic hyperaccumulating and non-accumulating plants

Arsenic (As) contamination generated from both natural phenomena and excessive application of arsenical pesticides in agricultural lands has resulted in elevated levels of arsenic in soils. The USEPA listed arsenic as one of the most hazardous substances controlled due to its harmful effects of various arsenic compounds on plant and animal tissues. Remediation of arsenic-contaminated soil and water is necessary for protecting both human life and agricultural production. Phytoremediation becomes a viable option to remediate arsenic-contaminated soils, mainly because it is cost-effective and environmentally friendly. A hyper-accumulating plant (Pteris vittata) can tolerate and accumulate large amounts of As. Currently, little information is available regarding the physiological and biochemical mechanism of As hyper-accumulation in the plant. The research purpose was to investigate arsenic stress response and detoxification mechanisms in arsenic hyperaccumulating and non-accumulating plants. Both greenhouse and laboratory experiments were conducted. To determine arsenic uptake potential and response to stress, Oryza sativa and Pteris vittata were grown in various soils with various concentrations of sodium arsenate and dimethylarsenic acid (DMA). The experiment was a 2*2*2*2*3 randomized design. After 6-month planting, final growth, arsenic concentration, and enzymatic activities were detected. In addition, to investigate the rate of arsenic accumulation by monocot seedlings in response to inorganic and organic arsenic pesticide application, a laboratory-based study was carried out in Oryza sativa and Zea mays seedlings grown in DMA and sodium arsenate solutions. The effects of increasing concentrations of sodium arsenate and competing phosphate on laboratory-grown Oryza sativa and Zea mays seedlings were investigated. Growth inhibition and biochemical stress response represented by the activities of Superoxide dismutase (SOD), Glutathione peroxidase (GPx), and Catalase (CAT) enzymes was observed. The results showed the characteristics and detoxification pathway of Oryza sativa, Zea mays, and Pteris vittata on their growth behavior and antioxidative production that were important to consider in phytoremediation factors. These characteristics might be of direct benefit in remediating As in contaminated soils.