No Statistic Correlation between Superoxide Dismutase and Peroxidase Activities and Aluminum-Induced Lipid Peroxidation in Maize, Implying Limited Roles of Both Enzymes in Prevention against Aluminum-Induced Lipid Peroxidation

摘要

Changes of and correlation among root tolerance index (RTI), root Aluminum (Al) content, root/shoot ratio (RSR), root malondialdehyde (MDA) content, and Superoxide dismutase (SOD) and peroxidase (POD) isoforms of maize YQ 7-96 were investigated under Al stress and removal of the stress (RS). Consequently, Al stress led to significant decreases in RTI, RSR, SOD and POD activities, but resulted in significant increase in root MD A and, Al accumulation in the tissues; Root SOD and POD activities did not correlate with Al and MDA contents in roots; The activities of SOD and POD were much lower in roots than in leaves. It can be concluded that (1) Al stress can lead to lipid peroxidation; (2) there is a larger POD family composed of different POD isoforms, some of which are of tissue-specific expression and play different roles in detoxification of Al in maize; (3) for POD isoforms, POD 2 is root-specific. POD 6 and POD 7 are all leaf-specific, POD 5 is not only root-specific but also RS-responsive; (4) high sensitivity of maize to Al is in part associated with much lower activities of both SOD and POD in roots; and (5) more importantly, both SOD and POD are therefore hinted to be not key players in prevention against Al-induced lipid peroxidation.