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This book describes nitric oxide (NO) and hydrogen peroxide (H2O2) functions in higher plants. Much progress has been made in the field of NO and H2O2 research regarding the various mechanisms and functions of these two molecules, particularly regarding stress tolerance and signaling processes, but there are still gaps to be filled. NO and H2O2 are both crucial regulators of development, and act as signaling molecules at each step of the plant lifecycle, while also playing important roles in biotic and abiotic responses to environmental cues. The book summarizes key advances in the field of NO and H2O2 research, focusing on a range of processes including: signaling, metabolism, seed germination, development, sexual reproduction, fruit ripening, and defense.

This book provides an overview of antioxidants and antioxidant enzymes and their role in the mechanisms of signaling and cellular tolerance under stress in plant systems. Major reactive oxygen species (ROS)-scavenging/modulating enzymes include the superoxide dismutase (SOD) that dismutates O2 into H2O2, which is followed by the coordinated action of a set of enzymes including catalase (CAT), ascorbate peroxidase (APX), glutathione peroxidase (GPX) and peroxiredoxins (Prx) that remove H2O2. In addition to the ROS scavenging enzymes, a number of other enzymes are found in various subcellular compartments, which are involved in maintaining such redox homeostasis either by directly scavenging particular ROS and ROS-byproducts or by replenishing antioxidants. In that respect, these enzymes can be also considered antioxidants. Such enzymes include monodehydroascorbate reductase (MDAR), dehydroascorbate reductase (DHAR), glutathione reductase (GR), alternative oxidases (AOXs), peroxidases (PODs) and glutathione S-transferases (GSTs). Some non-enzymatic antioxidants, such as ascorbic acid (vitamin C), carotenes (provitamin A), tocopherols (vitamin E), and glutathione (GSH), work in concert with antioxidant enzymes to sustain an intracellular steady-state level of ROS that promotes plant growth, development, cell cycles and hormone signaling, and reinforces the responses to abiotic and biotic environmental stressors. Offering a unique compilation of information on antioxidants and antioxidant enzymes, this is a valuable resource for advanced students and researchers working on plant biochemistry, physiology, biotechnology, and signaling in cell organelles, and those specializing in plant enzyme technology.

This book provides an up-to-date overview of redox signaling in plant cells and its key role in responses to different stresses. The chapters, which are original works or reviews, focus on redox signaling states; cellular tolerance under different biotic and abiotic stresses; cellular redox homeostasis as a central modulator; redox homeostasis and reactive oxygen species (ROS); redox balance in chloroplasts and mitochondria; oxidative stress and its role in peroxisome homeostasis; glutathione-related enzyme systems and metabolism under metal stress; and abiotic stress-induced redox changes and programmed cell death. The book is an invaluable source of information for plant scientists and students interested in redox state chemistry and cellular tolerance in plants.

This book provides detailed and comprehensive information on oxidative damage caused by stresses in plants with especial reference to the metabolism of reactive oxygen species (ROS).In plants, as in all aerobic organisms, ROS are common by-products formed by the inevitable leakage of electrons onto O2 from the electron transport activities located in chloroplasts, mitochondria, peroxisomes and in plasma membranes or as a consequence of various metabolic pathways confined in different cellular loci. Environmental stresses such as heat, cold, drought, salinity, heavy-metal toxicity, ozone and ultraviolet radiation as well as pathogens/contagion attack lead to enhanced generation of ROS in plants due to disruption of cellular homeostasis. ROS play a dual role in plants; at low concentrations they act as signaling molecules that facilitate several responses in plant cells, including those promoted by biotic and abiotic agents. In divergence, at high levels they cause damage to cellular constituents triggering oxidative stress. In either case, small antioxidant molecules and enzymes modulate the action of these ambivalent species.

Plants possess a range of potential cellular mechanisms that may be involved in the detoxification of heavy metals and thus tolerance to metal stress. Metal toxicity causes multiple direct and indirect effects in plants that concern practically all physiological functions. The main purpose of this book is to present comprehensive and concise information on recent advances in the field of metal transport and how genetic diversity affects heavy metal transport in plants. Other key futures of the book are related to metal toxicity and detoxification mechanisms, biochemical tools for HM remediation processes, molecular mechanisms for HM detoxification, how metallomics and metalloproteomics are affected by heavy metal stress in plants, and the role of ROS metabolism in the alleviation of heavy metals. Some chapters also focus on recent developments in the field of phytoremediation. Overall the book presents in-depth information and the most essential advances in the field of heavy metal toxicity in plants in recent years.