Oxidative Stress in Plants and Its Management
We all live in an oxygen-rich environment which has to deal with the danger of oxidative stress. During normal cell metabolism, reactive oxygen species (ROS) are constantly produced, mainly by respiratory and photosynthetic components. These species mainl
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Abstract
We all live in an oxygen-rich environment which has to deal with the danger of oxidative stress. During normal cell metabolism, reactive oxygen species (ROS) are constantly produced, mainly by respiratory and photosynthetic components. These species mainly include superoxide radicals (O2), singlet oxygen (1O2), hydrogen peroxide (H2O2), and hydroxyl radical (OH). The others are hydroperoxyl radical (HO2˙), alkoxy radical (RO˙), peroxyl radicals (ROO˙), and excited carbonyl (RO). But during stress conditions like salinity, drought, metal toxicity, herbicides, fungicides, air pollutants, hypoxia, and abnormal conditions of light, temperature, and topography, ROS are produced in excess amount. These highly reactive molecules can react with many cellular biomolecules and other components and damage DNA, proteins, and lipids. Thus, their concentration has to be tightly controlled. To counter the deleterious effects of ROS, aerobic organisms are equipped with antioxidant systems to scavenge ROS from the cells. Enzymatic antioxidants are mainly superoxide dismutase (SOD), catalase, ascorbate peroxidase, glutathione peroxidase, glutathione S-transferases, and peroxiredoxin, while the nonenzymatic antioxidants are mainly ascorbate, glutathione, proline, tocopherol, flavonoids, and carotenoids. These antioxidants protect against the oxidative damage by inhibiting or quenching free radicals and ROS. When the balance between the production of ROS and the quenching activities of antioxidants is disturbed, the cell faces the risk of oxidative stress and damage. These ROS creating stresses are numerous and often species or area specific. These stresses cause significant crop losses. There is a growing need to develop crops which can be resistant to the effects of various oxidative stresses. One such way is to develop transgenic plants overexpressing one or more
S. Teotia (*) D. Singh School of Biotechnology, Gautam Buddha University, Greater Noida 201312, India e-mail: [email protected] R.K. Gaur and P. Sharma (eds.), Approaches to Plant Stress and their Management, DOI 10.1007/978-81-322-1620-9_13, # Springer India 2014
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antioxidants, which can confer resistance towards particular stress. Another way is to develop mutants which are resistant towards certain stresses. Keywords
Reactive oxygen species Oxidative stress tolerance Enzymatic Antioxidants Nonenzymatic antioxidants Transgenic plants and mutants
Introduction Oxygen is the primary source of life. In an oxygen atmosphere, the generation of ROS, especially under metabolic stress, is unavoidable. ROS are also produced continuously as by-products of various metabolic pathways localized in different cellular compartments such as chloroplast, mitochondria, peroxisomes, and apoplast (del Rio et al. 2006; Panieri et al. 2013). Many metabolic processes normally produce ROS, which comprise mainly of superoxide radical, hydrogen peroxide, hydroxyl radical, and singlet oxygen. ROS may also be produced by abiotic stress such
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