Effect of Ascorbate on the Arsenic Uptake, ROS-scavenging Capacity, and Antioxidant Homeostasis in Rice

Environmental pollution with arsenic (As) in croplands causes agricultural and health problems worldwide. Rice is an important crop in South Korea, and many studies have evaluated the relationship between As and glutathione (GSH) to alleviate As uptake from the soil into plants. However, information about the relationship between As and ascorbate (AsA) in rice seedlings is still limited with regard to As phytotoxicity. We therefore investigated changes in reactive oxygen species (ROS) and antioxidant levels in rice (Oryza sativa L. cv 'Dasan') seedlings with toxic As and/or AsA application. The exposure of rice seedlings to $15{\mu}M$ As inhibited plant growth and resulted in increased contents of superoxide, hydrogen peroxide, and malondialdehyde, and induced As uptake by the roots and leaves. Application of AsA to As-exposed seedlings ameliorated As-induced oxidative stress by enhancing the capacity of AsA-GSH cycle in applied plants and increasing As transfer from the roots to leaves. These results suggest that AsA application alleviated As-induced oxidative damage by maintaining sufficient levels of AsA and GSH.