Role of sulfate in detoxification of arsenate-induced toxicity in Zea mays L. (SRHM 445): Nutrient status and antioxidants

The study highlights the role of sulfur (S) in detoxification of arsenate-induced toxicity and the shift in essential element homeostasis in Zea mays L (SRHM 445). Overall growth of arsenate-treated plants under sulfur starvation (-S) was lower than that in the presence of excess sulfur (+S). Translocation of arsenate from roots to shoots, increased under As(-S) and decreased with As(+S). The level of micronutrients (Cu, Zn, Fe) increased in As(-S) plants. Whereas, the level of K and PO₄ was higher in As(-S) plants than in As(+S) plants. Higher malondialdehyde, protein carbonyl, and H₂O₂ levels in As(-S) plants are indicative of higher oxidative stress. Higher superoxide dismutase (SOD) and ascorbate peroxidase (APX) activities, in As(-S) plants coincided with higher H₂O₂ levels showing the activity of these enzymes are independent of S availability. Absence of reduced glutathione/oxidized glutathione pool in (-S) plants manifested into failure of ascorbate-glutathione detoxification pathway. Hence, S has dual role of protecting the plant against arsenate-induced toxicity (1) by restricting arsenic (As) translocation to the upper parts and (2) by increasing the activity SOD and APX.