Over-expression of Sub1A, a submergence tolerance gene from rice, confers enhanced hypoxic stress tolerance in transgenic tobacco plants
Sub1A, an ethylene-response-factor-like (ERE-like) gene, mediates the extinguished submergence tolerance of rice. To gain further insight into the function of Sub1A in other species, we transformed tobacco plants with the gene under the control of the ubiquitin promoter. Compared to the wild-type plants, transgenic plants over-expressing Sub1A exhibited a greater ability to adapt to hypoxia, as evidenced by the highly induced activities of enzymes (pyruvate decarboxylase and alcohol dehydrogenase) regulating ethanolic fermentation. Furthermore, Sub1A upregulated activities of the main antioxidant enzymes, such as superoxide dismutase, ascorbate peroxidase and catalase, making the transgenic plants scavenge reactive oxygen species (ROS) more effectively. This was further confirmed by the less accumulation of malondialdehyde, an end product of lipid peroxidation. Taken together, our results suggest that Sub1A promotes plants hypoxic stress tolerance by regulating genes involved in anaerobic metabolism as well as ROS amelioration. In addition, it also suggests that Sub1A can be used potentially to improve hypoxic stress tolerance in plant breeding.
Key words: Hypoxic stress, Sub1A, Tobacco, transgenic plants.