MANIPULATION OF GLUTATHIONE-REDUCTASE IN TRANSGENIC PLANTS - IMPLICATIONS FOR PLANTS RESPONSES TO ENVIRONMENTAL-STRESS

The activities of a number of enzymes of the ascorbate-glutathione pat hway have been shown to rise under conditions of increased oxidative s tress. The potential to alter the expression of specific enzymes of th is pathway by genetic manipulation has provided the opportunity to att empt to develop transgenic plants with altered levels of oxidative str ess defense enzymes which should have improved stress tolerances. We h ave cloned a cDNA for glutathione reductase from a higher plant (Pisum sativum L.) and have used this to construct chimeric genes for the ex pression of the pea enzyme in the chloroplast, mitochondrion or cytoso l of transgenic tobacco plants. Some of the transformed lines with ele vated levels of expression of glutathione reductase accumulate higher concentrations of glutathione and show increased tolerance to paraquat , however, no evidence was found for elevated tolerance to ozone fumig ation.