Reactive Oxygen Species Generation, Scavenging and Signaling in Plant Defense Responses

Abstract

Plants grow in an environment of abiotic stresses such as drought, high light (HL) intensity, heat, salinity, metal/metalloid, or a combination of these environmental stresses requires a delicate balance between energy production and consumption, to mention normal energy. Reactive oxygen species (ROS), a by-product of aerobic metabolism, are key signaling molecules which play a significant role in plants’ responses to myriad of abiotic and biotic stresses. ROS initially evidenced as only damaging factors in plants further were found to play an important role in numerous signaling pathways that mediate plants’ acclimatory and defense responses. The production and scavenging of ROS are accomplished in various cellular compartments such as the apoplast, cell membrane, mitochondria, chloroplasts, peroxisomes, and endoplasmic reticulum. Under abiotic stresses, an imbalance between ROS biosynthesis and scavenging and elimination in favor of biosynthesis with certain consequences for plant cell physiology has been termed as “oxidative stress.” Regulation of redox environment and ROS signals via the cross talk of ROS with various signaling agents within plants’ cell requires a high degree of coordination in different cellular compartments. In this present chapter, we provide an update on ROS generation, scavenging, and redox signaling in the context of plant abiotic stress tolerance. Unraveling destabilizing and stabilizing factors of ROS homeostasis and signaling in plants under biotic and abiotic stress environment may provide a detailed exploration of ROS/antioxidative signature-related kinetics that can help in designing new and sustainable innovative ways and means for (a) mounting proper acclimation response, (b) monitoring/increasing overall plants’ fitness in improving health and productivity of plants under the influence of various stress conditions, and (c) identification and characterization of new targets and key regulator ROS-signaling transduction pathways which may provide excellent future candidates for breeding/engineering stress-resilient crop plants.