Increased Resistance to Oxidative Stress in Transgenic Plants that Overexpress Chloroplastic Cu/Zn Superoxide Dismutase

• Published in: Proceedings of the National Academy of Sciences - PNAS 1993-02, Vol.90 (4), p.1629-1633
• Main Authors: Gupta, Ashima Sen, Heinen, Jeanie L., Holaday, A. Scott, Burke, John J., Allen, Randy D.
• Format: Article
• Language: English
• Subjects: Base Sequence; Botany; Chimera; Chloroplasts; Chloroplasts - enzymology; Codon - genetics; Cold Temperature; Genes; Genotypes; Isoenzymes - genetics; Isoenzymes - isolation & purification; Isoenzymes - metabolism; Leaves; Light; Macromolecular Substances; Nicotiana - drug effects; Nicotiana - enzymology; Nicotiana - genetics; Nicotiana - physiology; Nicotiana tabacum; Oxidative stress; Paraquat - pharmacology; Peas; Photosynthesis; Plants; Plants, Genetically Modified; Plants, Toxic; Protein isoforms; Restriction Mapping; Superoxide Dismutase - genetics; Superoxide Dismutase - isolation & purification; Superoxide Dismutase - metabolism; Superoxides; Tobacco; Transgenic plants
• ISSN: 0027-8424; 1091-6490
• DOI: 10.1073/pnas.90.4.1629

Transgenic tobacco plants that express a chimeric gene that encodes chloroplast-localized Cu/Zn superoxide dismutase (SOD) from pea have been developed. To investigate whether increased expression of chloroplasttargeted SOD could alter the resistance of photosynthesis to environmental stress, these plants were subjected to chilling temperatures and moderate (500 μ mol of quanta per m2per s) or high (1500 μ mol of quanta per m2per s) light intensity. During exposure to moderate stress, transgenic SOD plants retained rates of photosynthesis ≈20% higher than untransformed tobacco plants, implicating active oxygen species in the reduction of photosynthesis during chilling. Unlike untransformed plants, transgenic SOD plants were capable of maintaining nearly 90% of their photosynthetic capacity (determined by their photosynthetic rates at 25⚬C) following exposure to chilling at high light intensity for 4 hr. These plants also showed reduced levels of light-mediated cellular damage from the superoxide-generating herbicide methyl viologen. These results demonstrate that SOD is a critical component of the active-oxygen-scavenging system of plant chloroplasts and indicate that modification of SOD expression in transgenic plants can improve plant stress tolerance.