Antioxidant Defense Systems in Plants: Mechanisms, Regulation, and Biotechnological Strategies for Enhanced Oxidative Stress Tolerance

Abstract

Plants must contend with oxidative stress, a paradoxical phenomenon in which reactive oxygen species (ROS) can cause cellular damage while also serving as key signaling molecules. Environmental stressors, such as drought, salinity, and temperature extremes, promote ROS accumulation, affecting plant growth and productivity. To maintain redox homeostasis, plants rely on antioxidant systems comprising enzymatic defenses, such as superoxide dismutase, catalase, and ascorbate peroxidase, and non-enzymatic molecules, including ascorbate, glutathione, flavonoids, and emerging compounds such as proline and nano-silicon. This review provides an integrated overview of antioxidant responses and their modulation through recent biotechnological advances, emphasizing the role of emerging technologies in advancing our understanding of redox regulation and translating molecular insights into stress-resilient phenotypes. Omics approaches have enabled the identification of redox-related genes, while genome editing tools, particularly those based on clustered regularly interspaced short palindromic repeats (CRISPR) and CRISPR-associated (Cas) proteins, offer opportunities for precise functional manipulation. Artificial intelligence and systems biology are accelerating the discovery of regulatory modules and enabling predictive modeling of antioxidant networks. We also highlight the contribution of synthetic biology to the development of stress-responsive gene circuits and address current regulatory and ethical considerations. Overall, this review aims to provide a comprehensive perspective on molecular, biochemical, and technological strategies to enhance oxidative stress tolerance in plants, thereby contributing to sustainable agriculture and food security in a changing climate.

Keywords: CRISPR/Cas systems; ROS; antioxidant defense; crop resilience; omics; oxidative stress; redox signaling; synthetic biology.

Figure 1

Schematic representation of the ascorbate–glutathione cycle. Ascorbate scavenges ROS, leading to DHA formation. DHA is reduced back to ascorbate by DHAR using GSH as electron donor, while GR regenerates GSH from GSSG, sustaining redox homeostasis. Arrows indicate the direction of the reactions in the ascorbate–GSH cycle.

Figure 2

Epigenetic regulation of plant responses to abiotic (e.g., heat, drought, cold) and biotic (e.g., pathogens, herbivores) stress. These environmental cues induce chromatin modifications, including histone methylation (H3K4me3 for transcriptional activation, H3K27me3 for repression), histone acetylation (H3K9ac for chromatin relaxation), and DNA methylation changes. Together, these epigenetic marks modulate the transcription of stress-responsive genes, enabling redox regulation, priming, and the establishment of stress memory.

Figure 3

Integrated framework for antioxidant defense in plants. The three interconnected gears represent Multilayered Regulation (ROS signaling, hormonal integration, epigenetics), Omics and Validation (genomics, transcriptomics, metabolomics), and Applications (transgenic lines, CRISPR editing, synthetic biology, MAS/AI-based breeding), highlighting their continuous interaction to enhance oxidative stress tolerance.

Figure 4

Integration of omics sciences and AI for plant genetic optimization under stress conditions. Multi-omics platforms (genomics, transcriptomics, proteomics, and metabolomics) generate high-dimensional datasets that, when analyzed using AI and machine learning algorithms, support the identification of key genes, regulatory networks, and stress-responsive traits. This integrated approach enables targeted breeding and genetic optimization of plants for improved resilience to environmental stressors.