Reactive Oxygen Species: Friend or Foe

Abstract

Climate change and associated unfavorable abiotic stress conditions, such as drought, salinity, heavy metals, water logging, extreme temperatures, oxygen deprivation, etc., influence plant growth and development to a great extent, eventually disturbing crop yield and quality, finally food security in general. Plant cells produce oxygen radicals and their derivatives, so-called reactive oxygen species (ROS), during different processes related with abiotic stress. Further, the ROS generation is a primary process in higher plants and operates to transmit signaling information at the cellular level in response to the change in environmental conditions. One of the most critical outcomes of abiotic stress is the disruption of the balance between the ROS generation and antioxidant defense systems inducing the excessive ROS accumulation and thus oxidative stress in plants. Remarkably, both enzymatic and nonenzymatic antioxidant defense mechanisms are known to maintain equilibrium between the detoxification and ROS generation under adverse environmental stresses. Even though this area of research has been captivated with massive attention, it mostly remains unfathomed, and our understanding of ROS signaling remains poorly understood. In this chapter, we have highlighted the current advancement demonstrating the detrimental effects of ROS, antioxidant defense systems implicated in ROS detoxification during various abiotic stresses, and molecular cross-talk with other key signal molecules such as reactive nitrogen, sulfur, and carbonyl species. Besides, state-of-the-art molecular strategies of ROS-mediated enhancement in antioxidant defense under the acclimation process in response to abiotic stresses in plants have also been covered.