Manipulation of glutathione reductase in transgenic plants: implications for plants' responses to environmental stress

Abstract

SynopsisThe activities of a number of enzymes of the ascorbate–glutathione pathway have been shown to rise under conditions of increased oxidative stress. The potential to alter the expression of specific enzymes of this pathway by genetic manipulation has provided the opportunity to attempt to develop transgenic plants with altered levels of oxidative stress defense enzymes which should have improved stress tolerances. We have cloned a cDNA for glutathione reductase from a higher plant (Pisum sativum L.) and have used this to construct chimeric genes for the expression of the pea enzyme in the chloroplast, mitochondrion or cytosol of transgenic tobacco plants. Some of the transformed lines with elevated 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 fumigation.

Dissecting the integrative antioxidant and redox systems in plant mitochondria. Effect of stress and S-nitrosylation

“…Similarly, the regulation of the GR has been proved to efficiently respond to different stresses ( Creissen et al, 1994 ). A cytosolic GR gene was found induced in a pea salt tolerant, but not in the salt-sensitive, cultivar ( Hernández et al, 2000 ) and the induction of the symplastic GR activity was higher in the tolerant plants, at the same time as increased DHAR and MDHAR activities.…”

Bitkilerde Tuz Toleransının Fizyolojik ve Biyokimyasal Bileşenleri

“…GR, APOD gibi askorbat-glutatyon döngüsünde rol oynayan bir enzimdir ve indirgenmiş glutatyon havuzunu besleyerek AOT' lere karşı savunmanın önemli bir parçasını oluşturur. GR büyük oranda kloroplastlarda bulunmasına ragmen, mitokondri ve sitoplazmada da gözlenmiştir [180]. GR, okside durumdaki glutatyonu (GSSG) NADPH molekülünden aldığı bir elektronu kullanarak indirgenmiş forma (GSH) dönüştürür [181].…”

Antioxidative responses to drought and salinity stress in plants, a comprehensive review

“…GR catalyzes the rate-limiting last step of asorbateglutathione cycle and maintains high ratio of reduced to oxidized glutathione (Noctor and Foyer, 1998). It is localized predominantly in chloroplasts, but small amount of this enzyme has also been found in mitochondria and cytosol (Creissen et al, 1994). …”