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