Enhanced Tolerance to Photooxidative Stress of Transgenic Nicotiana tabacum with High Chloroplastic Glutathione Reductase Activity

A gene from Escherichia coli that encodes glutathione reductase was connected to a gene for a chloroplastic transit-peptide and the 35S promoter of cauliflower mosaic virus. This chimeric gene was introduced into tobacco cells for generation of transgenic plants. Expression of the transgene in leaf cells and accumulation of the product of its translation in chloroplasts of the transgenic plants were confirmed immunochemically. Leaves of some transgenic plants had activities of glutathione reductase that were about 3-fold higher than those of control plants. These transgenic plants exhibited lower susceptibility both to paraquat and to sulfur dioxide in the light than the control plants in terms of the extent of visible foliar damage. These results suggest that the chloroplastic glutathione reductase, a component of the system for scavenging active oxygen, plays a role in the resistance of plants to photooxidative stress caused by paraquat or sulfur dioxide.