An Introduction to Antioxidants and Their Roles in Plant Stress Tolerance
Various abiotic stresses lead to the formation of reactive oxygen species (ROS) in plants which are highly reactive and toxic in plant cell. The ROS comprises both free radical (superoxide radicals, O2 −; hydroxyl radical, OH−; perhydroxyl radical, HO2 −;
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An Introduction to Antioxidants and Their Roles in Plant Stress Tolerance Neeti Mehla, Vinita Sindhi, Deepti Josula, Pooja Bisht, and Shabir H. Wani
Abstract
Various abiotic stresses lead to the formation of reactive oxygen species (ROS) in plants which are highly reactive and toxic in plant cell. The ROS comprises both free radical (superoxide radicals, O2; hydroxyl radical, OH; perhydroxyl radical, HO2; and alkoxy radicals, RO) and non-radical (molecular) forms such as hydrogen peroxide (H2O2) and singlet oxygen (O2). Chloroplasts and mitochondria are the major sites for the generation of O2. Plant’s abiotic stress tolerance requires a number of physiological and biochemical mechanisms which includes enzymatic (superoxide dismutase, SOD; catalase, CAT; ascorbate peroxidase, APX; glutathione reductase, GR; monodehydroascorbate reductase, MDHAR; dehydroascorbate reductase, DHAR; glutathione peroxidase, GPX; guaiacol peroxidase, GPOX; and glutathione-S-transferase, GST) and non-enzymatic (ascorbic acid, ASH; glutathione, GSH; phenolic compounds; alkaloids; flavonoids; carotenoids; non-protein amino acids; and α-tocopherols). Increased environmental stresses imbalance the production of reactive oxygen species and thereby quench the activity of antioxidants and thus N. Mehla • P. Bisht Department of Botany, Sri Venkateswara College, University of Delhi, Delhi 110021, India V. Sindhi Biological Sciences, Sri Venkateswara College, University of Delhi, Delhi 110021, India D. Josula Life Sciences, Sri Venkateswara College, University of Delhi, Delhi 110021, India S.H. Wani (*) Division of Genetics and Plant Breeding, Faculty of Agriculture WADURA, Sher-e-Kashmir University of Agricultural Sciences and Technology, Srinagar, Jammu and Kashmir 191121, India Department of Plant, Soil and Microbial Sciences, Michigan State University, East Lansing, MI 48824-1325, USA e-mail: [email protected]; [email protected] # Springer Nature Singapore Pte Ltd. 2017 M.I.R. Khan, N.A. Khan (eds.), Reactive Oxygen Species and Antioxidant Systems in Plants: Role and Regulation under Abiotic Stress, DOI 10.1007/978-981-10-5254-5_1
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resulting in oxidative damage. ROS can cause damage to cell structures, nucleic acids, lipids and proteins. Certain ROS like OH- ions are said to react with all components of DNA and damage the purines and pyrimidines. The increased production of antioxidants thus helps the plant to withstand the environmental stress. This chapter focuses on the description of antioxidant defence system under abiotic stress in plants and its involvement in the removal of reactive oxygen species. Hence various types of antioxidants, their types and role will be discussed in detail. Keywords
Abiotic stress • Antioxidant defence system • Reactive oxygen species (ROS) • Oxidative stress
Abbreviations 1O
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ABA APX AsA AsA-GSH ASH ATP Ca2+ Car Cars CAT Cd Cu/ZnSOD Cys DHAR DNA FeSOD GB GDH GPOX GPX GR GSH GSSG GST
Singlet oxygen Abscisic acid Ascorbate peroxidase Ascorbate Ascorbate-glutathione
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