Glutathione in plants: an integrated overview

Abstract

Plants cannot survive without glutathione (g-glutamylcysteinylglycine) or g-glutamylcysteinecontaining homologues. The reasons why this small molecule is indispensable are not fully understood, but it can be inferred that glutathione has functions in plant development that cannot be performed by other thiols or antioxidants. The known functions of glutathione include roles in biosynthetic pathways, detoxification, antioxidant biochemistry and redox homeostasis. Glutathione can interact in multiple ways with proteins through thiol-disulphide exchange and related processes. Its strategic position between oxidants such as reactive oxygen species and cellular reductants makes the glutathione system perfectly configured for signalling functions. Recent years have witnessed considerable progress in understanding glutathione synthesis, degradation and transport, particularly in relation to cellular redox homeostasis and related signalling under optimal and stress conditions. Here we outline the key recent advances and discuss how alterations in glutathione status, such as those observed during stress, may participate in signal transduction cascades. The discussion highlights some of the issues surrounding the regulation of glutathione contents, the control of glutathione redox potential, and how the functions of glutathione and other thiols are integrated to fine-tune photorespiratory and respiratory metabolism and to modulate phytohormone signalling pathways through appropriate modification of sensitive protein cysteine residues.

Transcriptomics of induced defense responses to greenbug aphid feeding in near isogenic wheat lines

“…The GSTs in plants have antioxidant properties that can scavenge ROS and other toxic compounds, maintain redox homeostasis, and mediate biosynthesis of certain defense molecules; however, specific function vary by the class [66][67][68]. Our study identified altered expression of seven transcripts putatively associated with GSTs in response to greenbug infestation (Fig.…”

Nitric oxide affects salt-induced changes in free amino acid levels in maize

“…The protective effect of NO on tolerance to osmotic stress was mediated by GSH in Agropyron cristatum (Shan et al, 2012). NO-dependent changes in the amount and redox potential of glutathione may protect plants from stress-induced injuries directly by the removal of the excess of reactive oxygen species and indirectly by activation of defence mechanisms and adjustment of metabolism to the altered environmental conditions (Noctor et al, 2012). In addition, the role of the other components of redox system in the mediation of the effect of NO on the response to salt stress is indicated by the increased expression of GR and APX in the leaves of maize treated with DETA/NO + NaCl in the present study.…”

Glutathione – linking cell proliferation to oxidative stress

“…However, accumulating evidence demonstrates that GSH is required for the operation of a diverse range of processes that include growth, stress tolerance and cell suicide programs (1,2). Within this context, the requirement for GSH is undoubtedly linked to signalling function, particularly interactions with nitric oxide (NO) and participation in thiol-dependent post-translational protein modifications, which modulate activities, sub-cellular localization, stability or their interactions with partner proteins in plants and animals.…”

“…It is rather surprising therefore that the nuclear GSH pool is much more resistant to depletion than the cytosolic pool, a property that is particularly important during cell proliferation (5)(6)(7)(8). Although relatively little is known about the nuclear thioredoxins (TRX) and glutaredoxins (GRXs) or their functions in plants (9) it is probable that these redox proteins participate in the plethora of thiol-dependent redox regulation mechanisms and post-translational modifications that are required for plant growth and development, particularly through functions in the nuclei.The many important roles of glutathione in plants have been well documented in recent reviews (1,2,10) and hence the following discussion will focus on how GSH functions as a regulator of plant development, with a particular focus on the nuclear GSH and the regulation of mitosis.…”