Plants are sessile organisms that live under a constant barrage of biotic and abiotic insults. Both biotic and abiotic stress factors have been shown to affect various aspects of plant system including the acceleration in the formation of reactive oxygen species (ROS). The ascorbate (AsA)-glutathione (GSH) pathway is a key part of the network of reactions involving enzymes and metabolites with redox properties for the detoxification of ROS, and thus to avert the ROS-accrued oxidative damage in plants. The present book mainly deals with the information gained through the cross-talks and inter-relationship studies on the physiological, biochemical and molecular aspects of the cumulative response of various components of AsA-GSH pathway to stress factors and their significance in plant stress tolerance.

Ascorbic acid (AsA), vitamin C, is one of the most abundant water-soluble antioxidant in plants and animals. In plants AsA serves as a major redox buffer and regulates various physiological processes controlling growth, development, and stress tolerance. Recent studies on AsA homeostasis have broadened our understanding of these physiological events. At the mechanistic level, AsA has been shown to participate in numerous metabolic and cell signaling processes, and the dynamic relationship between AsA and reactive oxygen species (ROS) has been well documented. Being a major component of the ascorbate-glutathione (AsA-GSH) cycle, AsA helps to modulate oxidative stress in plants by controlling ROS detoxification alone and in co-operation with glutathione. In contrast to the single pathway responsible for AsA biosynthesis in animals, plants utilize multiple pathways to synthesize AsA, perhaps reflecting the importance of this molecule to plant health. Any fluctuations, increases or decreases, in cellular AsA levels can have profound effects on plant growth and development, as AsA is associated with the regulation of the cell cycle, redox signaling, enzyme function and defense gene expression. Although there has been significant progress made investigating the multiple roles AsA plays in stress tolerance, many aspects of AsA-mediated physiological responses require additional research if AsA metabolism is to be manipulated to enhance stress-tolerance. This book summarizes the roles of AsA that are directly or indirectly involved in the metabolic processes and physiological functions of plants. Key topics include AsA biosynthesis and metabolism, compartmentation and transport, AsA-mediated ROS detoxification, as well as AsA signaling functions in plant growth, development and responses to environmental stresses. The main objective of this volume is therefore to supply comprehensive and up-to-date information for students, scholars and scientists interested in or currently engaged in AsA research.

Glutathione (γ-glutamyl-cysteinyl-glycine) is a ubiquitously distributed sulfurcontaining antioxidant molecule that plays key roles in the regulation of plant growth, development, and abiotic and biotic stress tolerance. It is one of the most powerful low-molecular-weight thiols, which rapidly accumulates in plant cells under stress. Recent in-depth studies on glutathione homeostasis (biosynthesis, degradation, compartmentalization, transport, and redox turnover) and the roles of glutathione in cell proliferation and environmental stress tolerance have provided new insights for plant biologists to conduct research aimed at deciphering the mechanisms associated with glutathione-mediated plant growth and stress responses, as well as to develop stress-tolerant crop plants. Glutathione has also been suggested to be a potential regulator of epigenetic modifications, playing important roles in the regulation of genes involved in the responses of plants to changing environments. The dynamic relationship between reduced glutathione (GSH) and reactive oxygen species (ROS) has been well documented, and glutathione has been shown to participate in several cell signaling and metabolic processes, involving the synthesis of protein, the transport of amino acids, DNA repair, the control of cell division, and programmed cell death. Two genes, gamma-glutamylcysteine synthetase (GSH1) and glutathione synthetase (GSH2), are involved in GSH synthesis, and genetic manipulation of these genes can modulate cellular glutathione levels. Any fluctuations in cellular GSH and oxidized glutathione (GSSG) levels have profound effects on plant growth and development, as glutathione is associated with the regulation of the cell cycle, redox signaling, enzymatic activities, defense gene expression, systemic acquired resistance, xenobiotic detoxification, and biological nitrogen fixation. Being a major constituent of the glyoxalase system and ascorbate-glutathione cycle, GSH helps to control multiple abiotic and biotic stress signaling pathways through the regulation of ROS and methylglyoxal (MG) levels. In addition, glutathione metabolism has the potential to be genetically or biochemically manipulated to develop stress-tolerant and nutritionally improved crop plants. Although significant progress has been made in investigating the multiple roles of glutathione in abiotic and biotic stress tolerance, many aspects of glutathione-mediated stress responses require additional research. The main objective of this volume is to explore the diverse roles of glutathione in plants by providing basic, comprehensive, and in-depth molecular information for advanced students, scholars, teachers, and scientists interested in or already engaged in research that involves glutathione. Finally, this book will be a valuable resource for future glutathione-related research and can be considered as a textbook for graduate students and as a reference book for frontline researchers working on glutathione metabolism in relation to plant growth, development, stress responses, and stress tolerance.

Presents the latest knowledge of improving the stress tolerance, yield, and quality of rice crops One of the most important cereal crops, rice provides food to more than half of the world population. Various abiotic stresses—currently impacting an estimated 60% of crop yields—are projected to increase in severity and frequency due to climate change. In light of the threat of global food grain insecurity, interest in molecular rice breeding has intensified in recent years. Progress has been made, but there remains an urgent need to develop stress-tolerant, bio-fortified rice varieties that provide consistent and high-quality yields under both stress and non-stress conditions. Molecular Breeding for Rice Abiotic Stress Tolerance and Nutritional Quality is the first book to provide comprehensive and up-to-date coverage of this critical topic, containing the physiological, biochemical, and molecular information required to develop effective engineering strategies for enhancing rice yield. Authoritative and in-depth chapters examine the molecular and genetic bases of abiotic stress tolerance, discuss yield and quality improvement of rice, and explore new approaches to better utilize natural resources through modern breeding. Topics Include rice adaptation to climate change, enriching rice yields under low phosphorus and light intensity, increasing iron, zinc, vitamin and antioxidant content, and improving tolerance to salinity, drought, heat, cold, submergence, heavy metals and Ultraviolet-B radiation. This important resource: Contains the latest scientific information on a wide range of topics central to molecular breeding for rice Provides timely coverage molecular breeding for improving abiotic stress tolerance, bioavailability of essential micronutrients, and crop productivity through biotechnological methods Features detailed chapters written by internationally-recognized experts in the field Discusses recent progress and future directions in molecular breeding strategies and research Molecular Breeding for Rice Abiotic Stress Tolerance and Nutritional Quality is required reading for rice researchers, agriculturists, and agribusiness professionals, and the ideal text for instructors and students in molecular plant breeding, abiotic stress tolerance, environmental science, and plant physiology, biochemistry, molecular biology, and biotechnology.

Ascorbate acid (AsA) is an important antioxidant in plants, playing important roles in various physiological processes. Humans have lost the ability to synthesize AsA because of the lack of L-gulono-1,4-lactone oxidoreductase, and thus have to absorb ascorbate from diet including fresh fruits and vegetables, as they are the major sources of ascorbate. Several pathways for AsA biosynthesis and metabolism have been identified in plants since 1998. More attention has been paid to improving ascorbate content in plants especially in fruits and vegetables. Significant progresses have been made on key enzymes and genes involved in the AsA biosynthesis and metabolism. Recently, more interests have arised in the regulation of AsA biosynthesis, as it is constantly regulated by the plant development and the environmental factors, e.g. light. Ascorbic acid is also frequently reported to affect plant growth and development e.g. flowering time and fruit ripening. The scope of the book is to cover the biological role, biosynthesis and metabolism, regulation, and metabolic modification of ascorbate in plants.

A guide to the chemical agents that protect plants from various environmental stressors Protective Chemical Agents in the Amelioration of Plant Abiotic Stress offers a guide to the diverse chemical agents that have the potential to mitigate different forms of abiotic stresses in plants. Edited by two experts on the topic, the book explores the role of novel chemicals and shows how using such unique chemical agents can tackle the oxidative damages caused by environmental stresses. Exogenous application of different chemical agents or chemical priming of seeds presents opportunities for crop stress management. The use of chemical compounds as protective agents has been found to improve plant tolerance significantly in various crop and non-crop species against a range of different individually applied abiotic stresses by regulating the endogenous levels of the protective agents within plants. This important book: Explores the efficacy of various chemical agents to eliminate abiotic stress Offers a groundbreaking look at the topic and reviews the most recent advances in the field Includes information from noted authorities on the subject Promises to benefit agriculture under stress conditions at the ground level Written for researchers, academicians, and scientists, Protective Chemical Agents in the Amelioration of Plant Abiotic Stress details the wide range of protective chemical agents, their applications, and their intricate biochemical and molecular mechanism of action within the plant systems during adverse situations.

Abiotic stress cause changes in soil-plant-atmosphere continuum and is responsible for reduced yield in several major crops. Therefore, the subject of abiotic stress response in plants - metabolism, productivity and sustainability - is gaining considerable significance in the contemporary world. Abiotic stress is an integral part of “climate change,” a complex phenomenon with a wide range of unpredictable impacts on the environment. Prolonged exposure to these abiotic stresses results in altered metabolism and damage to biomolecules. Plants evolve defense mechanisms to tolerate these stresses by upregulation of osmolytes, osmoprotectants, and enzymatic and non-enzymatic antioxidants, etc. This volume deals with abiotic stress-induced morphological and anatomical changes, abberations in metabolism, strategies and approaches to increase salt tolerance, managing the drought stress, sustainable fruit production and postharvest stress treatments, role of glutathione reductase, flavonoids as antioxidants in plants, the role of salicylic acid and trehalose in plants, stress-induced flowering. The role of soil organic matter in mineral nutrition and fatty acid profile in response to heavy metal stress are also dealt with. Proteomic markers for oxidative stress as a new tools for reactive oxygen species and photosynthesis research, abscisic acid signaling in plants are covered with chosen examples. Stress responsive genes and gene products including expressed proteins that are implicated in conferring tolerance to the plant are presented. Thus, this volume would provides the reader with a wide spectrum of information including key references and with a large number of illustrations and tables. Dr. Parvaiz is Assistant Professor in Botany at A.S. College, Srinagar, Jammu and Kashmir, India. He has completed his post-graduation in Botany in 2000 from Jamia Hamdard New Delhi India. After his Ph.D from the Indian Institute of Technology (IIT) Delhi, India in 2007 he joined the International Centre for Genetic Engineering and Biotechnology, New Delhi. He has published more than 20 research papers in peer reviewed journals and 4 book chapters. He has also edited a volume which is in press with Studium Press Pvt. India Ltd., New Delhi, India. Dr. Parvaiz is actively engaged in studying the molecular and physio-biochemical responses of different plants (mulberry, pea, Indian mustard) under environmental stress. Prof. M.N.V. Prasad is a Professor in the Department of Plant Sciences at the University of Hyderabad, India. He received B.Sc. (1973) and M.Sc. (1975) degrees from Andhra University, India, and the Ph.D. degree (1979) in botany from the University of Lucknow, India. Prasad has published 216 articles in peer reviewed journals and 82 book chapters and conference proceedings in the broad area of environmental botany and heavy metal stress in plants. He is the author, co-author, editor, or co-editor for eight books. He is the recipient of Pitamber Pant National Environment Fellowship of 2007 awarded by the Ministry of Environment and Forests, Government of India.