Oxidative stress response induced in an atrazine phytoremediating plant: physiological responses of Pennisetum glaucum to high atrazine concentrations.

This research presented here, for the first time, elucidates the responses of several antioxidants in Pennisetum leaves exposed to varying concentrations of atrazine (0 - 200 mg•kg-1). Pennisetum has been reported to be resistant to atrazine; however, its physiological response to high concentrations (≥ 50 mg•kg-1) of atrazine is not well documented. The contents of reduced (AsA) and oxidized (DHA) ascorbate increased significantly with increase in atrazine concentration and exposure time; but the increase was more evident under higher (50 and 100 mg•kg-1) atrazine concentrations. Increase in atrazine concentration to 200 mg•kg-1 significantly decreased AsA, but increased DHA content, throughout the experiment. Seedlings treated with 200 mg•kg-1 atrazine showed significantly lowest reduced glutathione (GSH) content; while oxidized glutathione (GSSG) was not significantly affected, after 68d. Seedlings treated with 100 mg•kg-1 atrazine showed increased Glutathione-S-Transferase (GST) activity after 48 d and 68 d; while treatment with 200 mg•kg-1 atrazine significantly increased Glutathione reductase (GR) after 58d. This result suggests that Pennisetum may tolerate lower atrazine concentrations; However, higher concentrations (≥50 mg•kg-1) which could have longer residency period in the soil, could induce more physiological damage to the plant.