ROS and Antioxidants: Relationship in Green Cells

Abstract

The redox homeostasis of plant cell, which largely depends on prooxidant and antioxidant status, is perturbed under environmental assault. In fact, the imposition of abiotic and biotic stresses changes redox status or homeostasis of the plant cell toward prooxidants and leads to a condition called oxidative stress. Orchestrated antioxidative defense that largely comprises of information-rich redox buffers and enzymes ensues to combat the situation, specifically at the site of action of the stress. Thus, the functional roles of these antioxidative defense responses include the restoration of metabolic redox homeostasis, the protection of the photosynthetic machinery, the preservation of membrane integrity, the protection of nucleic acids and proteins, etc. Current progress of work suggests that complex regulatory mechanisms function at both the gene expression and protein level to coordinate antioxidant responses in plants. To ensure survival, particularly under stress, plants have developed both enzymatic and nonenzymatic defense systems which work hand in hand not only to scavenge ROS but also to tightly regulate the endogenous titer of ROS to induce the signaling role of ROS, required for stress acclimation. Growing body of evidence suggests the role of redox homeostasis under environmental stress in which ROS-antioxidant interaction acts at metabolic interface for signal derived from unfavorable environmental cues. The current research also suggest the function of antioxidants as key arbitrator of intracellular redox status and exhibit high degree of potential with their differential cellular status permitting antioxidant-driven vectorial signaling. In this chapter, an effort has been made to detail the different antioxidative defense mechanisms operating in the cellular and subcellular level for scavenging ROS and maintaining redox homeostasis under stressful conditions. Further, a descriptive account regarding antioxidant-based redox information which influences gene expression associated with unfavorable environmental conditions to maximize defense is also discussed.