Department of Horticulture, Oregon State University, Corvallis, OR, 97331- 7304, USA; USDA-ARS, 45 Wiltshire Road, Kearneysville, WV, 25430-9606, USA, Forestry & Natural Resource Department, Purdue University, West Lafayette, IN, 47907-2072, USA, Departme
Journal of Applied Horticulture, 2007, volume 9, issue 1, pages 3-8.
Abstract: Production of reactive oxygen species (ROS) is associated with a number of physiological disorders in plants. Superoxide dismutase (SOD) catalyzes the breakdown of superoxide (O2-) into O2 and H2O2 and provides the first line of defense against the toxic effects of elevated levels of ROS. The effect of increased expression of Mn superoxide dismutase (Mn-SOD) on salt stress tolerance was studied using transformed tomato (Lycopersicon esculentum cv. Zhongshu No. 5) plants. Northern blots confirmed expression of the heterologous Mn-SOD in transgenic plants. Strong Mn-SOD enzyme activity was detected by native PAGE in transformed plants. Transgenic plants showed resistance to the superoxide-generating herbicide methyl viologen (MV, 10-4 M). The total SOD activity was one and one half- to two-fold higher, and APX (ascorbate peroxidase) activity was six to seven fold higher in transgenic, than in wild-type (WT) plant under MV stress. Germination of transgenic tomato seeds at a NaCl concentration of 150 mM was greater than wild-type seeds. When exposed to salt stress, roots of transgenic plants were less stunted and leaf injury was lower than that observed in WT plants. Also, the total APX activity of transgenic plants was 4 to 5 fold higher than that of WT under NaCl (200 mM) stress.