Excess Copper-Induced Changes in Antioxidative Enzyme Activity, Mineral Nutrient Uptake and Translocation in Sugarcane Seedlings.

Sugarcane is a potential species for use in heavy metal remediation. To analyze the effect of excess copper on sugarcane, the biomass, mineral nutrient content and activities of antioxidative enzymes were measured under copper stress. The results revealed that the biomass of roots and shoots significantly decreased with increasing copper concentration in solution. Most copper accumulated in the roots, and the translocation factor of copper decreased with an increase in copper stress. The MDA content in sugarcane roots notably increased under copper stress. The POD activity in sugarcane roots increased, and CAT activity decreased under copper stress. The Zn, Fe and Mn contents in shoots increased significantly under 200 µmol L-1 Cu2+ treatments. The Zn and Mg contents in roots notably decreased under copper stress, while the Zn and Mg translocation factors increased. These results indicated that the increase in POD activity and the modification of mineral nutrient uptake and transfer might play an important role in reducing the detrimental effects of excess copper.

Genotypic Differences in Growth and Antioxidant Enzyme Activities Under Cadmium Stress in Sugarcane.

To evaluate the genotypic differences of sugarcane in response to cadmium (Cd) stress, the growth, Cd content, antioxidant enzymes, malondialdehyde (MDA) and proline in the leaves of five sugarcane varieties were investigated under normal and Cd-contaminated soil at 90 days after treatment (DAT). Height, diameter, and biomass significantly decreased in all varieties under Cd stress, with the greatest reduction in HOCP07-613 and less effects on YT666 and YT94-128. The Cd content in sugarcane markedly increased under Cd stress. Cd stress induced a significant increase in MDA contents in HOCP07-613 and ROC22 at 90 DAT and a greater increase in proline content in YT94-128 and YT666. The activities of superoxide dismutase (SOD), guaiacol peroxidase (POD), catalase (CAT) and ascorbate peroxidase (APX) were affected by Cd stress in four varieties (excluding YT666). The increase in SOD and APX activities in the early stage of Cd stress (30 DAT) might help alleviate oxidative stress in sugarcane. These results suggested that the different responses of antioxidant systems to Cd stress might affect Cd tolerance of sugarcane.