Glutathione homeostasis: Crucial for abiotic stress tolerance in plants

Abstract

Glutathione is a non-protein low molecular weight tripeptide that plays an important role in cell function and metabolism. The cellular glutathione/glutathione disulfide redox buffer provides homeostasis by maintaining the redox state of other thiol compounds, avoiding their unnecessary oxidation and thus keeping them in the reduced state. Besides involvement in ascorbate-glutathione cycle, glutathione is also critical for the detoxification of xenobiotics, sequestration of heavy metals and other processes involved in environmental stress tolerance. Involvement of glutathione in post-translational modification by the process of glutathionylation prevents proteins from oxidation. The reversible formation of a mixed disulfide between glutathione and cysteine residue on the target protein brings about conformational changes and alters the activity of several important proteins through signaling cascade. The precise mechanisms involved in the formation of mixed-disulfides in vivo are largely unknown especially in higher plants. Glutaredoxins catalyze the reverse reaction of glutathionylation which is known as deglutathionylation. Environmental stresses affect the redox status of the cell which 'in turn' triggers signaling cascade pathway(s) leading to the altered physiology of the plants. In this chapter, an attempt has been made to highlight the involvement of glutathione in redox regulation and its crosstalk with other pathways particularly under environmental stresses in plants. © 2010 Springer Science + Business Media B.V. All Rights Reserved.