Cerium Oxide Nanoparticles Modify the Antioxidative Stress Enzyme Activities and Macromolecule Composition in Rice Seedlings

摘要

Cerium oxide nanoparticles (nCeO_2) have been shown to have significant interactions in plants; however, there are limited reports on their impacts in rice (Oryza sativa). Given the widespread environmental dispersal of nCeO_2 it is paramount to understand its biochemical and molecular impacts on a globally important agricultural crop, such as rice. This study was carried out to determine the impact of nCeO_2 on the oxidative stress, membrane damage, antioxidant enzymes' activities, and macromolecular changes in the roots of rice seedlings. Rice seeds (medium amylose) were grown for 10 days in nCeO_2 suspensions (0-500 mg L~(-1)). Results showed that Ce in root seedlings increased as the external nCeO_2 increased without visible signs of toxicity. Relative to the control, the 62.5 mg nCeO_2 L~(-1) reduced the H_2O_2 generation in the roots by 75%. At 125 mg nCeO_2 L~(-1) the roots showed enhanced lipid peroxidation and electrolyte leakage, while at 500 mg L~(-1), the nCeO_2 increased the H_2O_2 generation in roots and reduced the fatty acid content. The lignin content decreased by 20% at 500 mg nCeO_2 L~(-1), despite the parallel increase in H_2O_2 content and peroxidase activities. Synchrotron μ-XRF confirmed the presence of Ce in the vascular tissues of the roots.