Chromium detoxification mechanism induced growth and antioxidant responses in vetiver ( Chrysopogon zizanioides (L.) Roberty)

This study investigated the chromium (Cr) detoxification mechanism-induced changes in growth and antioxidant defence enzyme activities in Chrysopogon zizanioides . Plant growth decreased by 36.8% and 45.0% in the shoots and roots, respectively, in the 50 mg/L Cr treatment. Cr accumulation was higher in root (9807 μg/g DW) than in shoots (8730 μg/g DW). Photosynthetic pigments and malondialdehyde content increased up to the 30 mg/L Cr treatment, whereas they declined at higher doses. The activity of superoxide dismutase (SOD), catalase (CAT) and peroxidase (POX) were increased significantly with increasing of Cr dose but slightly declined at higher doses. Isozyme banding patterns revealed the expression of multiple bands for SOD, CAT and POX enzymes, and the band intensity decreased at high doses of Cr exposure. These results indicate that higher Cr doses increased the oxidative stress by over production of reactive oxygen species (ROS) in vetiver that had potential tolerance mechanism to Cr as evidenced by enhanced level of antioxidative enzymes, photosynthetic pigments, MDA contents. Therefore, vetiver has evolved a mechanism for detoxification and accumulates higher concentration of toxic Cr. This study provides a better understanding of how vetiver detoxifies Cr.