Transgenic Arabidopsis overexpressing Mn-SOD enhanced salt-tolerance

The Mn-SOD is a critical enzyme eliminating reactive oxygen species (ROS) in plant cells under environmental stresses, but the roles of Mn-SOD in plant cells under salt stress remains elusive. This study focuses on the effects of Mn-SOD overexpressed in transgenic Arabidopsis on salt tolerance. We have constructed the transgenic Arabidopsis overexpressing Mn-SOD, the activity of which was more than two-fold over that of wild type. When treated with 150mM NaCl, the transgenic plants grew well, while the wild type plants withered gradually, this indicated the transgenic Arabidopsis enhanced salt-tolerance. Further analyses showed that not only the activities of Mn-SOD but also the activities of other antioxidative enzymes such as Cu/Zn-SOD, Fe-SOD, catalase (CAT) and peroxidase (POD) of transgenic plants treated by 150mM NaCl were markedly higher than those of wild type plants, and the contents of malondialdehyde (MDA) were lower than those of wild type under 150mmol/L NaCl treatment, indicating the ability of eliminating ROS in transgenic Arabidopsis increased significantly. These results suggested that the Mn-SOD overexpressed in Arabidopsis played a pivotal role in preventing the over accumulation of ROS and protecting the cells against ROS caused by salt stress, as a result, enhanced salt-tolerance of the transgenic plants. This study will help explain the essential roles of Mn-SOD in adaptive responses of plant cells under environmental stresses. (C) 2004 Elsevier Ireland Ltd. All rights reserved.