Abstract

Plant growth and development and interactions with the environment are regulated by phytohormones and other signaling molecules. During their evolution, plants have developed strategies for efficient signal perception and for the activation of signal transduction cascades to maintain proper growth and development, in particular under adverse environmental conditions. Abscisic acid (ABA) is one of the phytohormones known to regulate plant developmental events and tolerance to environmental stresses. The role of ABA is mediated by both its accumulated level, which is regulated by its biosynthesis and catabolism, and signaling, all of which are influenced by complex regulatory mechanisms. Under stress conditions, plants employ enzymatic and non-enzymatic antioxidant strategies to scavenge excess reactive oxygen species (ROS) and mitigate the negative effects of oxidative stress. Glutathione (GSH) is one of the main antioxidant molecules playing a critical role in plant survival under stress conditions through the detoxification of excess ROS, maintaining cellular redox homeostasis and regulating protein functions. GSH has recently emerged as an important signaling molecule regulating ABA signal transduction and associated developmental events, and response to stressors. This review highlights the current knowledge on the interplay between ABA and GSH in regulating seed dormancy, germination, stomatal closure and tolerance to drought.

Highlights

  • Plants are sessile in nature and are constantly exposed to a variety of environmental conditions that negatively affect their growth, development and productivity

  • Genetic studies have revealed that the loss of function of genes involved in Abscisic acid (ABA) metabolism or signaling affects plant developmental processes and leads to a decrease in stress tolerance [6,7]

  • ABA signaling in plants involves three core components, namely, pyrabactin resistance (PYR)/pyrabactin resistance-like (PYL)/regulatory component of ABA receptors (RCAR) (PYR/PYL/RCAR), type 2C protein phosphatases (PP2Cs), which act as negative regulators of ABA signaling, and sucrose non-fermenting-1-(SNF1)-related protein kinase 2 (SnRK2) that acts as a positive regulator of ABA signaling [28,29]

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Summary

Introduction

Plants are sessile in nature and are constantly exposed to a variety of environmental conditions that negatively affect their growth, development and productivity. Glutathione is a water-soluble low molecular weight non-protein tripeptide (γ-glutamylcysteinyl-glycine) that serves as the most abundant thiol source in plant cells [10] It is involved in several plant growth and developmental processes including regulation of cellular redox homeostasis and gene expression, and plant response to biotic and abiotic stress factors [11,12,13]. Several studies have demonstrated the role of GSH in enhancing plant tolerance to a variety of abiotic stressors including drought, cold, salinity, high temperature and metal toxicity [19,20,21] Plant hormones such as ABA are implicated in modulating the intracellular GSH/GSSG ratios under abiotic stress conditions [22,23]. Inactive ABA-GEs can be rapidly converted to active ABA by ABA-GE hydrolyzing enzymes, beta-glycosidases [27]

ABA Signaling
Glutathione Biosynthesis and Metabolism
Glutathione-Mediated ABA Signaling in Drought Tolerance
Conclusions and Future Prospects
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