Resistance to Active Oxygen Toxicity of Transgenic Nicotiana tabacum that Expresses the Gene for Glutathione Reductase from Escherichia coli

A chimeric gene consisting of a gene from Escherichia coli that encodes glutathione reductase (GR), the 35S promoter of cauliflower mosaic virus and the terminator sequences of the gene for nopaline synthase, was introduced into tobacco (Nicotiana tabacum SRI) cells via a Ti plasmid vector. Expression of the bacterial gene in transformed plants and their descendants was confirmed by immunochemical analysis. GR activity in leaf extracts varied among transgenic plants, ranging from about 1.0 to 3.5 times the control level. These transgenic plants exhibited lower susceptibility to paraquat than control plants in terms of the extent of visible foliar damage, a result that suggests that GR may play an important role in the detoxification of active oxygen in the cytoplasmic matrix of plant cells. However, the transgenic plants were no more resistant to ozone than were the controls, both in terms of the extent of visible foliar damage and with respect to photosynthetic activity.