Drought and Salt Stress Tolerance of an Arabidopsis Glutathione S-Transferase U17 Knockout Mutant Are Attributed to the Combined Effect of Glutathione and Abscisic Acid      

Abstract

Although glutathione S-transferases (GSTs) are thought to play major roles in oxidative stress metabolism, little is known about the regulatory functions of GSTs. We have reported that Arabidopsis (Arabidopsis thaliana) GLUTATHIONE S-TRANSFERASE U17 (AtGSTU17; At1g10370) participates in light signaling and might modulate various aspects of development by affecting glutathione (GSH) pools via a coordinated regulation with phytochrome A. Here, we provide further evidence to support a negative role of AtGSTU17 in drought and salt stress tolerance. When AtGSTU17 was mutated, plants were more tolerant to drought and salt stresses compared with wild-type plants. In addition, atgstu17 accumulated higher levels of GSH and abscisic acid (ABA) and exhibited hyposensitivity to ABA during seed germination, smaller stomatal apertures, a lower transpiration rate, better development of primary and lateral root systems, and longer vegetative growth. To explore how atgstu17 accumulated higher ABA content, we grew wild-type plants in the solution containing GSH and found that they accumulated ABA to a higher extent than plants grown in the absence of GSH, and they also exhibited the atgstu17 phenotypes. Wild-type plants treated with GSH also demonstrated more tolerance to drought and salt stresses. Furthermore, the effect of GSH on root patterning and drought tolerance was confirmed by growing the atgstu17 in solution containing L-buthionine-(S,R)-sulfoximine, a specific inhibitor of GSH biosynthesis. In conclusion, the atgstu17 phenotype can be explained by the combined effect of GSH and ABA. We propose a role of AtGSTU17 in adaptive responses to drought and salt stresses by functioning as a negative component of stress-mediated signal transduction pathways.

Influence of traumatic acid on growth and metabolism of Chlorella vulgaris under conditions of salt stress

“…The present study showed that C. vulgaris treated with NaCl at concentrations 10 -7 -10 -4 M was characterized by a smaller number of algae cells compared to the controls. This finding is consistent with data in literature according to which the salinity inhibits mitotic divisions, causes a slowdown in the elongation growth of cells, and, ultimately, reduces the rate of growth of leaves and roots (Munns and Tester 2008;Chen et al 2012).…”

Glutathione in plants: biosynthesis and physiological role in environmental stress tolerance

“…Moreover, Physiol Mol Biol Plants (April-June 2017) 23(2):249-268 253 supplementation of wild type plants with exogenous GSH resulted in higher ABA content and a similar phenotype to that seen in the mutant, as well as greater drought tolerance. Glutathione application induced higher levels of ABA, the plant hormone that controls seed germination, regulates stomatal aperture, and reduces transpiration rate (Chen et al 2012). Drought stress resulted in leaf rolling in Ctenanthe setosa (Rosc.)…”

“…GST expression in plants is induced by phytohormones such as SA, ethylene, cytokinin, auxin, ABA (Marrs 1996), methyl jasmonate (Moons 2003), and brassinosteroids (Deng et al 2007). Chen et al (2012) demonstrated that GST overexpressed in Arabidopsis thaliana plants had a signaling role and it regulated plant development by maintaining GSH pools. The mutant plant atgstu17 synthesized higher levels of GSH and ABA when compared to the wild type.…”

“…Exogenously applied GSH can improve abiotic stress tolerances in plants (Kattab 2007;Salama and AlMutawa 2009;Wang et al 2011;Wu et al 2011;Chen et al 2012;Nahar et al 2015a, b, c). In this review, we concentrate on the biosynthesis and metabolism of GSH and its roles in plants under environmental stress conditions, focusing on recent research findings on GSH and abiotic stress tolerance.…”

Glutathione S-Transferase activities and glutathione levels in needles of drought stressed Pinus brutia Ten. trees

“…This molecule has many other functions in plant cells including even the induction of the transcription of gst genes [19] Under environmental stress conditions, plants raise the concentration of GSH in especially foliar tissues as a part of their acclimation strategy via antioxidative defense systems [30]. However, Chen et al [31] concluded that the higher ratio of reduced to oxidized GSH or, glutathione / glutathione disulfide (GSH/GSSG), the rate of GSH biosynthesis and the capacity of its redox cycling, rather than GSH accumulation, might be essential for drought resistance in plants; so, one could/couldn't measure elevated glutathione levels, or even decreased levels might be detected. This means that, even if there observed little change in GSH amount during summer period, the GSH/GSSG redox state might be changed towards being more oxidized, more reduced, or not at all.…”