Dedication
To my Nana, Mohammad Habib (July 12, 1899–August 03, 1991)
A philanthropist, untold freedom fighter and retired as Treasury Officer from Azamgarh, in 1954. A Founder Member and Treasurer of Sukhpura Inter College, Ballia, India
Contributors xi
About the editor xv
Preface xvii
1. Plants and their unexpected response to environmental pollution: An overview
Shakeelur Rahman, Sahil Mehta, and Azamal Husen
1. Introduction 1
2. Plant response to air pollution 4
3. Plant response to photochemical oxidants 6
4. Plant response to light pollution 8
5. Plant response to soil pollution 10
6. Plant response to water pollution 11
7. Plant response to noise pollution 12
8 Plant response to nanoparticles 14
9. Conclusion 15
References 16
2. Effect of UV-B radiation on plants growth, active constituents, and productivity
Irina F. Golovatskaya and Nikolay I. Laptev
1. Introduction 26
2. Physiological reactions of plants in response to UV-B-radiation 28
3. UV-B signaling in the plant 35
4. Plants protection mechanisms from the negative effects of UV-B 45
5. Applications of UV-B radiation in practice 52
6. Conclusion 54
References 54
Further reading 60
3. Effect of elevated CO2 on plant growth, active constituents, and production
Harmanjot Kaur, Antul Kumar, Anuj Choudhary, Shivam Sharma, D.R. Choudhary, and Sahil Mehta
1. Introduction 61
2. Current status of CO2 and historical perspectives 62
3. Effect of high CO2 on plant growth 64
4. Effect on the production of active constituents 69
5. Deleterious effect of alleviated CO2 on the plant architecture 71
6. Conclusion 73
References 73
4. Effect of elevated O3 on plants growth, active constituents, and production
Priti Chauhan and Neeti Sharma
1. Introduction 79
2. Chemistry of tropospheric O3 formation 80
3. Mechanisms by which O3 damages plant tissue 81
4. Volatile organic compounds (VOCs) 82
5. Toxicology of plants 83
6. The effects of ozone on plants 83
7. Measurements of ozone-induced changes 85
8. Visible injury and physiological effects 85
9. Effects on plant growth 86
10. Biochemical effects of O3 87
11. Productivity measurements 88
12. The impact on crops and trees 89
13. Ozone and reactive oxygen species 89
14. Ozone as a disinfectant for the surface 89
15. ROS and plant cell metabolism 90
16. Conclusion 90
References 91
5. Plants response to SO2 or acid deposition
Suchisree Jha and Ashok Yadav
1. Introduction 99
2. Plant and SO2 or acid rain 100
3. Plants response to SO2 or acid deposition 100
4. Plants develops their defense system 105
5. Conclusion 106 References 106
6. Fly ash toxicity, concerned issues and possible impacts on plant health and production
Saurabh Sonwani, Anshu Gupta, Pallavi Saxena, and Anita Rani
1. Introduction 109
2. Fly ash composition 111
3. Causes of fly ash toxicity 112
4. Impact of fly ash on crop health and productivity 113
5. Effects of heavy metals on plant metabolism and physiology 117
6. Conclusion 119 References 120
7. Effect of coal-smoke pollution on plants growth, metabolism and production
Saumya Srivastava, Rajlaxmi Singh, and Prahlad Arya (Kumar)
1. Introduction 125
2. Principal phytotoxic gases of coal burning and their impact on flora 126
3. Other gases/release of coal burning and their impact on vegetation of the world 129
4. Conclusion 134 References 134
8. Effect of heavy metals on growth, physiological and biochemical responses of plants
Arslan Hafeez, Rizwan Rasheed, Muhammad Arslan Ashraf, Freeha Fatima Qureshi, Iqbal Hussain, and Muhammad Iqbal
1. Introduction 139
2. Effect of heavy metal pollution on plants 140
3. Cadmium (Cd) 142
4. Lead (Pb) 145
5. Arsenic (As) 147
6. Mercury (Hg) 149
7. Metal stress tolerance mechanisms in plants 150
8. Conclusion 151
References 151
9. Interaction of nanoparticles and nanocomposite with plant and environment
Chandrabose Selvaraj, Chandrabose Yogeswari, and Sanjeev Kumar Singh
1. Introduction 162
2. Sources of nanomaterials 162
3. Classification of nanoparticles 163
4. Organization of nanomaterials based on their sizes 165
5. Types of nanomaterials based on their source 165
6. Types of nanoparticles related to plants 166
7. Cerium NPs (CeO NPs) 168
8. Silicon NPs (SiNPs) 168
9. Titanium dioxide NPs (TiO2 NPs) 169
10. Nano pesticides 170
11. Nanoemulsion 173
12. Interaction of NMs with soil and rhizosphere 173
13. Interaction of NMs with overall environment 174
14. Factors influencing the uptake and translocation of NPs 175
15. NPs for plant pathogen detection 178
16. Transport and interaction 179
17. Nanoparticle-plant interaction pathways 180
18. Effects of ion-releasing NP 181
19. Impact of natural organic material on NP-induced effects 182
20. Concluding remarks 183
Acknowledgment 183
References 183
10. Toxic effects of essential metals on plants: From damage to adaptation responses
Shivam Sharma, D.R. Choudhary, Viveka Katoch, Antul Kumar, Anuj Choudhary, B.M. Harish, Harmanjot Kaur, and Sahil Mehta
1. Introduction 195
2. Metal toxicity in plants 197
3. Metal toxicity and its damage detection 200
4. Repair strategies and plant response 202
5. Adaptation responses 203
6. Conclusion 205
References 205
11. Phytoremediation strategies of plants: Challenges and opportunities
Poonam Sharma, Smita Rai, Krishna Gautam, and Swati Sharma
1. Introduction 211
2. Mechanism of heavy metal remediation 214
3. Phytoremediation of contaminated soil to grow food 218
4. Phytoremediation for bioenergy production 220
5. Valorization of phytoremediation by-products 221
6. Challenges associated with phytoremediation 223
7. Conclusion and future perspective 224
References 225
12. Pesticide toxicity and their impact on plant growth, active constituents and productivity
Himani Gautam, Shubhra Singh, Hema Prashad, Antul Kumar, Anuj Choudhary, Harmanjot Kaur, Om Prakash Narayan, Shambhu Krishan Lal, and Sahil Mehta
1. Introduction 232
2. Phytotoxicity effects on plants 233
3. Pesticides phytotoxicity symptoms on plants 236
4. Impact of pesticide toxicity on soil health and plant 237
5. Other measures for the prevention of pesticides phytotoxicity 246
6. Conclusion 246
References 247
13. Plant responses to water pollution
Nirmal Singh, Sourabh, Pramod Kumar, Preeti, and Sahil Mehta
1. Introduction 253
2. Water pollution: Definition, types, and extent of the problem 254
3. Plant and water pollution 257
4. Concluding remarks 261
References 261
Further reading 263
14. Plant response to industrial waste
Sana Ashraf, Ayesha Anwar, Qasim Ali, Azna Safdar, and Kehkashan
1. Introduction 265
2. Types of plants 268
3. Response of plant to industrial waste 270
4. Conclusion 276 References 277
15. Radioisotopes and their impact on plants
K.F. Abdelmotelb, Shri Hari Prasad, Shivaji Ajinath Lavale, Akash Ravindra Chichaghare, and Sahil Mehta
1. Introduction to radioisotopes 283
2. Radioisotopes as pollutants 285
3. Effects of radiation on plant diversity 286
4. Effects of radiation in plant morphology 287
5. Effects of radiation in plant physiology and molecular biology 288
6. Radio-adaptation by plants 292
7. Use of radioisotopes in crop improvement: A positive side 294
8. Conclusion 294 References 295
16. Effects of cell phone radiation on plants growth, active constituents and production
Ashok Yadav and Suchisree Jha
1. Introduction 299
2. Plants and cell phone radiation or GSM radiation 300
3. Effects of cell phone radiation on plant system 300
4. Conclusion 304 References 305
17.
Effects of major munitions compounds on plant health and function
Stephen M. Via and Paul V. Manley
1. Warfare and the environment 309
2. Global munitions issue 311
3. Chemical relics of war 312
4. Environmental behavior 313
5. Explosives and vegetation 316
6. Monitoring going forward 320
References 325
Further reading 331
18. Aquatic macrophytes and trace elements: Deleterious effects, biomarkers, adaptation mechanisms, and potential new wave of phytoremediation processes
Maha Krayem, Sami El Khatib, and Pascal Labrousse
1. Introduction 334
2. Trace elements and aquatic plants or macrophytes 335
3. Biomarkers and adaptation mechanisms of macrophytes 338
4. Macrophytes: A potential new wave of phytoremediation processes 353
5. Conclusion 365 References 366
19. Production and role of plants secondary metabolites under various environmental pollution
Phaniendra Alugoju and Tewin Tencomnao
1. Introduction 380
2. Effect of elevated CO2 (EC) levels on PSMs 380
3. Effect of ozone (O3) on PSMs 390
4. Effect of toxic gases on the production of PSMs 393
5. Effect of heavy metals on PSMs 395
6. Effect of particulate matter (PM) on PSMs 399
7. Conclusion 401 References 401
20. Plant proteomics and environmental pollution
B.M. Harish, Shivam Sharma, D.R. Choudhary, Antul Kumar, Anuj Choudhary, Harmanjot Kaur, Manisha Lakhanpal, Wajahat Ali Khan, and Sahil Mehta
1. Introduction 411
2. Approaches and challenges in crop plant proteomics 413
3. Plant proteomic technologies—Recent innovations and their applications 413
4. Cellular proteome to subcellular protein catalogues 415
5. Organ-specific proteome analysis of plants in concern to environmental pollutants 420
6. Conclusion 423
References 423
21. Genetic modification and genome engineering of plants for adverse environmental pollution
Khushboo Singh, Geeta Boken, and Sahil Mehta
1. Introduction 429
2. Current scenario of globe and human towards pollution 430
3. Pollution: Effects on plants 431
4. Engineering plants 433
5. Conclusion and future prospects 436
References 436
Index 441
Contributors
K.F. Abdelmotelb Department of Genetics, Faculty of Agriculture, Zagazig University, Zagazig, Egypt
Qasim Ali Department of Soil Sciences, Faculty of Agriculture and Environment, The Islamia University of Bahawalpur, Bahawalpur, Pakistan
Phaniendra Alugoju Natural Products for Neuroprotection and Anti-Ageing Research Unit; Department of Clinical Chemistry, Faculty of Allied Health Sciences, Chulalongkorn University, Bangkok, Thailand
Ayesha Anwar Institute of Soil and Environmental Sciences, University of Agriculture, Faisalabad, Pakistan
Prahlad Arya (Kumar) Department of Geology, Patna Science College, Patna University, Patna, Bihar, India
Muhammad Arslan Ashraf Department of Botany, Government College University Faisalabad, Faisalabad, Pakistan
Sana Ashraf College of Earth and Environmental Sciences, Quaid-e-Azam Campus, University of the Punjab, Lahore, Pakistan
Geeta Boken Department of Genetics and Plant Breeding, CCS Haryana Agricultural University, Hisar, Haryana, India
D.R. Choudhary Department of Vegetable Science and Floriculture, CSK HPKV, Palampur, Himachal Pradesh, India
Priti Chauhan Department of Biosciences and Biotechnology, Banasthali Vidyapith, Jaipur, Rajasthan, India
Akash Ravindra Chichaghare Department of Silviculture and Agroforestry, Kerala Agricultural University, Thrissur, Kerala, India
Anuj Choudhary Department of Botany, Punjab Agricultural University, Ludhiana, Punjab, India
Sami El Khatib LIU, Lebanese International University, Al Khyara-West Bekaa, Lebanon
Himani Gautam Department of Entomology, Dr. YS Parmar University of Horticulture and Forestry, Nauni Solan, Himachal Pradesh, India
Krishna Gautam Centre for Energy and Environmental Sustainability, Lucknow, Uttar Pradesh, India
Irina F. Golovatskaya Department of Plant Physiology, Biotechnology and Bioinformatics, National Research Tomsk State University, Tomsk, Russia
Anshu Gupta Department of Environmental Science, Government Degree College, Jammu, India
Arslan Hafeez Department of Botany, Government College University Faisalabad, Faisalabad, Pakistan
B.M. Harish Department of Vegetable Science and Floriculture, CSK HPKV, Palampur, Himachal Pradesh, India
Azamal Husen Wolaita Sodo University, Wolaita, Ethiopia
Iqbal Hussain Department of Botany, Government College University Faisalabad, Faisalabad, Pakistan
Muhammad Iqbal Department of Botany, Government College University Faisalabad, Faisalabad, Pakistan
Suchisree Jha Plant Nutrition Department, Indofil Industries Limited, Thane, Maharashtra, India
Contributors
Viveka Katoch Department of Seed Science and Technology, CSK HPKV Palampur, Himachal Pradesh, India
Harmanjot Kaur Department of Botany, Punjab Agricultural University, Ludhiana, Punjab, India
Kehkashan Institute of Soil and Environmental Sciences, University of Agriculture, Faisalabad, Pakistan
Wajahat Ali Khan International Centre for Genetic Engineering and Biotechnology, New Delhi, Delhi, India
Maha Krayem LIU, Lebanese International University, Al Khyara-West Bekaa, Lebanon
Antul Kumar Department of Botany, Punjab Agricultural University, Ludhiana, Punjab, India
Pramod Kumar Department of Agronomy, CCS Haryana Agricultural University, Hisar, Haryana, India
Pascal Labrousse Université de Limoges, PEIRENE EA 7500, Limoges, France
Manisha Lakhanpal Department of Forest Products (Medicinal and Aromatic Plants), Dr YS Parmar university of Horticulture and Forestry, Nauni, Himachal Pradesh, India
Shambhu Krishan Lal School of Genetic Engineering, ICAR–Indian Institute of Agricultural Biotechnology, Ranchi, Jharkhand; International Centre for Genetic Engineering and Biotechnology, New Delhi, India
Nikolay I. Laptev Department of Ecology, Nature Management and Environmental Engineering, National Research Tomsk State University, Tomsk, Russia
Shivaji Ajinath Lavale Centre for Plant Biotechnology and Molecular Biology, Kerala Agricultural University, Thrissur, Kerala, India
Paul V. Manley Department of Civil, Architectural and Environmental Engineering, College of Engineering and Computing, Missouri University of Science and Technology, Rolla, MO, United States
Sahil Mehta Department of Botany, Hansraj College, University of Delhi, New Delhi, India
Om Prakash Narayan BME Department, Tufts University, Medford, MA, United States
Shri Hari Prasad Centre for Plant Biotechnology and Molecular Biology, Kerala Agricultural University, Thrissur, Kerala, India
Hema Prashad Department of Entomology, Dr. YS Parmar University of Horticulture and Forestry, Nauni Solan, Himachal Pradesh, India
Preeti ICAR-National Bureau of Plant Genetic Resources, New Delhi, India
Freeha Fatima Qureshi Department of Botany, Government College University Faisalabad, Faisalabad, Pakistan
Shakeelur Rahman Prakriti Bachao Foundation, Ranchi, Jharkhand, India
Smita Rai Department of Biosciences, Integral University, Lucknow, Uttar Pradesh, India
Anita Rani Department of Botany, Dyal Singh College, University of Delhi, Delhi, India
Rizwan Rasheed Department of Botany, Government College University Faisalabad, Faisalabad, Pakistan
Azna Safdar Institute of Soil and Environmental Sciences, University of Agriculture, Faisalabad, Pakistan
Pallavi Saxena Department of Environmental Sciences, Hindu College, University of Delhi, Delhi, India
Chandrabose Selvaraj Computer-Aided Drug Design and Molecular Modeling Lab, Department of Bioinformatics, Science Block, Alagappa University, Karaikudi, Tamil Nadu, India
Neeti Sharma Department of Biosciences and Biotechnology, Banasthali Vidyapith, Jaipur, Rajasthan, India
Poonam Sharma Department of Bioengineering, Integral University, Lucknow, Uttar Pradesh, India
Shivam Sharma Department of Vegetable Science and Floriculture, CSK HPKV, Palampur, Himachal Pradesh, India
Swati Sharma Department of Biosciences, Integral University, Lucknow, Uttar Pradesh, India
Khushboo Singh School of Agricultural Sciences, K.R. Mangalam University, Gurugram, Haryana, India
Nirmal Singh Department of Seed Science and Technology, CCS Haryana Agricultural University, Hisar, Haryana, India
Rajlaxmi Singh Department of Botany, Patna University, Patna, Bihar, India
Sanjeev Kumar Singh Computer-Aided Drug Design and Molecular Modeling Lab, Department of Bioinformatics, Science Block, Alagappa University, Karaikudi, Tamil Nadu, India
Shubhra Singh Department of Entomology, Dr. YS Parmar University of Horticulture and Forestry, Nauni Solan, Himachal Pradesh, India
Saurabh Sonwani Department of Environmental Studies, Zakir Husain Delhi College, University of Delhi, Delhi, India
Sourabh ICAR – Central Arid Zone Research Institute, Jodhpur, Rajasthan, India
Saumya Srivastava Department of Botany, Patna University, Patna, Bihar, India
Tewin Tencomnao Natural Products for Neuroprotection and Anti-Ageing Research Unit; Department of Clinical Chemistry, Faculty of Allied Health Sciences, Chulalongkorn University, Bangkok, Thailand; Department of Physiology, University of Kentucky, Lexington, KY, United States
Stephen M. Via Department of Biology, College of Science, Engineering, and Technology, Norfolk State University, Norfolk, VA, United States
Ashok Yadav ICAR-Central Agroforestry Research Institute, Jhansi, Uttar Pradesh, India
Chandrabose Yogeswari Ezhilnala Siddha Varma Hospital and Research Centre, Madurai, Tamil Nadu, India
Plants and their unexpected response to environmental pollution: An overview
Shakeelur Rahmana, Sahil Mehtab, and Azamal Husenc
aPrakriti Bachao Foundation, Ranchi, Jharkhand, India, bDepartment of Botany, Hansraj College, University of Delhi, New Delhi, India, cWolaita Sodo University, Wolaita, Ethiopia
Abbreviations
ATP adenosine tri-phosphate
CFCs chloro fluoro carbons
dB decibel
FR far-red
H2S hydrogen sulfide
HCl hydrogen chloride
HF hydrogen fluoride
NO2 nitrogen dioxide
NPs nanoparticles
NMs nanomaterials
PAN peroxy acetyl nitrate
PAR photosynthetically active radiation
R red
ROS reactive oxygen species
SPL sound pressure level
SOD superoxide dismutases
UV ultraviolet radiation
1. Introduction
Environmental pollution is one of the most complex problems in the modern world. Combustion of fossil fuels, urbanization, chemicals used in agriculture, traffic load, war weapons, airplanes, and industrialization results in increased emission of toxic gases. These
1. Plants and their unexpected response to environmental pollution are the major sources of pollution responsible for numerous impacts on the flora and fauna (Husen, 2021a,b,c, 2022). As a result, the chemical composition of the atmosphere has been distorted. In the present scenario, the increase in the concentration of greenhouse gases such as carbon monoxide (CO), carbon dioxide (CO2), nitrous oxides (NOx), methane (CH4), chlorofluorocarbons (CFCs), and ozone (O3) in the atmosphere is among the most major threats to the biodiversity. Overall, environmental pollution has tremendous impacts on plant growth, development, and physiological performance at the cellular and molecular levels (Husen, 2022; Deepti et al., 2022a,b; Rahman and Husen, 2022) (Fig. 1). The global rise of environmental pollution also leads to climate change causing visible impacts on life cycles and distribution of various plant species. The raised level of CO2 and sulfur dioxide (SO2) in the atmosphere is also affecting the productivity and quality of plants species, showing major changes in their chemical composition (Husen, 1997, 2022; Husen et al., 1999; Idso et al., 2000; Iqbal et al., 2018).
Plants absorb pollutants on the surface of leaves, and onto the plant root-soil system to mitigate global warming and minimize the pollution load in a particular area. Moreover, forests act as a purification system of the planet earth by absorbing airborne chemicals and releasing oxygen. However, another aspect is that water pollution gives sufficient space for other plants to grow well because the nutrients they need for existence are collected in the polluted water. Water pollution also modifies the growing environment of plants, such as the removal of essential nutrients and bringing in new and hazardous ones. Acid rain (mainly NO2 and SO2 deposition), also harm by burning or killing plants in a specific location. Soils and freshwaters are naturally acidic (pH < 7) owing to the oxidation and respiration reactions in biotic and abiotic systems. During the twentieth century, the acidity of many regions of the world continuously increased as a consequence of energy and food production.
FIG. 1 Plant response to various types of environmental pollution.
The phenomena and impacts of acid rain on vegetation create a complex situation for plants which ends up with the plants being unable to flourish. Acidic conditions accumulate a lot of aluminum ions in the soil, which destroys roots systems and prevents the uptake of important nutrients and ions (Lal, 2016).
Some plants, such as species of cactus bloom only in the dark at night. They are pollinated by bats and moths and other nocturnal animals or insects. Increasing the duration of light in such areas will disrupt the pollination and this affects plant's ability to flower and reproduce and this will ultimately disrupt our food sources. It is amazing to know that plants, like animals, are sensitive to light, intensity, color, and duration of exposure. Photosynthesis, therefore, requires blue and red lights of high intensity. Low-intensity red and infrared lights are good for regulating biological rhythms and controlling processes like seed germination, flower development, leaf expansion, stem elongation, etc. thus, light pollution perhaps, therefore affects all these biological phenomena.
Air pollution can affect plants directly through the leaves, as well as indirectly by the acidification of the soil environment (Iqbal et al., 1987, 2010a,b, 2011; Husen and Iqbal, 2004; Kumar and Nandini, 2013). The impacts of atmospheric pollution are generally observed on leaves because they are the first receptors (Randhi and Reddy, 2012). It has also been observed in different studies that the majority of plants exposed to a polluted atmosphere start many physiological changes before visible injuries to the leaves (Abida and Harikrishna, 2010). The study on environmental pollution in relation to anatomical, morphological, physiological, and biochemical parameters of plants has been conducted by several researchers (Husen, 2021a,b,c). Some of the biochemical mechanisms assist to acclimatize plants to atmospheric pollutants. It can be assessed by several parameters or air pollution tolerance indexes such as total chlorophyll, relative water content, ascorbic acid, and pH. Similarly, the tolerance of plants to heavy metal toxicity has to be established to judge their possible application in soil phyto stabilization and plantation in mining areas contaminated with heavy metals (Nadgorska-Socha et al., 2013a,b; Iqbal et al., 2015). A plant in stress delays flowering as it uses all its resources to face the threat. For example, most of the plants exposed to vehicular pollution, delay in flowering as they are fighting the emissions.
Another important concern is the depletion in the stratospheric O3 layer causes ultraviolet radiation (UV-B) radiation which is harmful not only to human health but also to plants and sea biota. It physically injures the plant leaves, causing abnormal yellowing of leaves or chlorosis. These results in a deficiency in chlorophyll, meaning the plant will not be able to make its own food or energy. With a higher concentration of O3, plant leaves will simply die due to too much exposure. Destruction by the O3 in the lower atmosphere restricts respiration, obstructs stomata, prevents photosynthesis, and stunts plant growth (Deepti et al., 2022a).
Plants have shown immediate (acute) and long (chronic) impacts of environmental pollution on plant growth and developmental processes (Husen, 1997, 2021c, 2022), which may depend on the types of plant species, exposure duration, concentration, and types of pollutants. It has been suggested that the anthropogenic or naturally produced pollutants interact with various plant species, and alter plant growth, development, biochemical physiological, and molecular performance. Moreover, their impact may vary according to the pollution source, pollutant types, season, exposure duration, plant species, leaf types, leaf thickness, presence of leaf hair or trichomes, epicuticular wax, etc. (Husen, 2021c, 2022). Taken together,
1. Plants and their unexpected response to environmental pollution this chapter reports the effect of various environmental pollution on plant growth and development, cytological, biochemical, physiological, and molecular responses.
2. Plant response to air pollution
The most significant anthropogenic phytotoxic gaseous air pollutants include nitrogen dioxide (NO2), O3, CO2, SO2, hydrogen sulfide (H2S), hydrogen chloride (HCl), hydrogen fluoride (HF), chlorine (Cl2), ethylene (C2H4), peroxyacetyl nitrate (PAN), and ammonia (NH3). These gases can be categorized according to their biochemical and physiological activity in plant cells as given in Table 1 (De Kok and Stulen, 1998).
The air pollutants that cause plant injury are most common near large cities, refineries, smelters, electric power plants, incinerators, refuse dumps, pulp and paper mills, and coal, gas, petroleum burning furnaces, other industries, airports, and highways. Several factors administer the level of injury and the area where air pollution is a problem, these are type and concentration of pollutants, length of exposure, distance from the source, meteorological conditions, and maturity of plant tissues, species, and variety of plants (Husen, 2021c, 2022). The extreme temperature, light, soil moisture deficit, and humidity recurrently modify the response of the plant to air pollutants. The impacts of pollutants on plants include burning at leaf tips or margins, blotchy foliage, twig dieback, premature leaf drop, delayed maturity, early drop of blossoms, stunted growth, and reduced yield. Generally, the visible injury to plants is of three types collapse of leaf tissue with the development of necrotic patterns, alterations in growth or premature loss of foliage, and yellowing or other color changes.
Air pollution injuries can create confusion with the symptoms caused by bacteria, fungi, nematodes, insects, viruses, toxicities, nutritional deficiencies as well as the adverse effects of water, temperature, and wind. SO2 is one of the key air pollutants which can get enter in the plant parts through roots as well as stomatal opening during photosynthesis and respiration. Young plants and matured leaves are most susceptible to SO2. SO2 injury can be severe 30 miles or more from its source. Injury, however, is generally highest in the surrounding area of the source. The degree of injury increases as both the concentration of sulfur dioxide and the length of exposure increase. Different responses of the plants against SO2 exposure have been reported (Rahman and Husen, 2022). It also depends on the plant species and different environmental factors (Rahman and Husen, 2022).
TABLE 1 The main metabolic activities of phytotoxic air pollutants in plants.
Air pollutant
O3, PAN
SO2, NO2, HF, HCl
SO2
SO2, NO2, H2S
NH3, NH4 +, NO2, NO
O3, PAN, SO2, HF, C2H4
Metabolic activity
Oxidizing
Acidifying
Mutagenic
Reducing
N-eutrophying
Disturbing hormonal balance
Plants are most sensitive to SO2 during periods of high relative humidity, bright sun, and adequate plant moisture during the late spring and early summer. Some of the responses are damaging photosystem, changes in the stomatal density, and deviations in the efficiency of carbon fixation (Swanepoel et al., 2007; Haworth et al., 2012; Husen, 2022). The exposure of succulent, broad-leaved plants to SO2 and its by-product sulfuric acid generally results in dry, white, or straw papery spots. Chronic injury causes brown to reddish-brown or black blotches on both surfaces of the leaf of some plant species. A tan to reddish-brown banding or dieback occurs on conifer leaves with adjoining areas. SO2 from the atmosphere along with H2S works as a sulfur source that can be up-taken through stomata of the plants other than the sulfate uptake from the roots. This stomatal uptake affects the metabolic profile of the plant.
Glucosinolates are sulfur-containing secondary metabolites that play an important function in sulfur storage which helps in the redistribution of sulfur during the sulfur-deprived condition (Falk et al., 2007). Two members from the genus Brassica were exposed to the 0.25 μL 1 of SO2 for seven days to examine the deviations in the glucosinolate content (Aghajanzadeh et al., 2015). The glucosinolate content was observed negligible change in the shoot under sulfur deprived as well as sufficient conditions. It has been reported that the high concentration of hydrogen sulfide (H2S) is responsible for leaf lesions, defoliation, tissue death and decreased growth rate in some plant species. H2S is also a signaling molecule that is proven to endorse the antioxidant activities in many plants against abiotic stresses. The application of H2S increased the antioxidant potential and quality in plants. Brassica oleracea was applied with the incrementing levels of sodium hydrosulfide (as an H2S donor) to check the physiological and antioxidative changes. It was observed that the lower levels of treatment showed increased contents of anthocyanins, flavonols, total phenolics, sinigrin, and carotenoids (Montesinos-Pereira et al., 2016). H2S has been also noted to mediate nicotine biosynthesis in Nicotiana tabacum when the growth of plants is induced under high temperatures. The element fluorine is found in fluorides compounds. Injury by particulate or gaseous fluorides is either a reddish brown or tan or yellowish mottle blistering at the tips and margin of broadleaved plants. A narrow, chlorotic to the dark brown band is mostly found between living and dead tissues (Chen et al., 2016). Many explanations related to plant response to SO2 pollution have been discussed in detail in the chapters to follow.
Further, greenhouse gases are major environmental challenge for a range of plant species (Husen, 2022; Choudhary et al., 2022). In this connection, CO2 is one of the key causes of a terrific rise since industrialization took place. Overall, the performance of plants to elevated CO2have shown both positive and negative responses. In terms of positive response, elevated CO2increased photosynthesis and subsequently higher growth, biomass, and plant yield (Ainsworth and Long, 2005; De Souza et al., 2008; van der Kooi et al., 2016). Though, in terms of negative response, elevated CO2has decreased a variety of nutrients including protein concentrations, vitamins, and macro- and microelements in plants (Myers et al., 2014; Fernando et al., 2015; Broberg et al., 2017; Thompson et al., 2019). Therefore, it is essential to understand the effect of elevated CO2 on plant growth and production. The elevated CO2 significantly affects photosynthetic features, metabolism, and plant development (Nowak et al., 2004; Ainsworth and Long, 2005).
It is assumed that C4 photosynthesis was saturated at ambient CO2 and that C4 plants might be less and/or not at all affected by the increased level of CO2 in comparison to C3 plant species (Pearcy and Ehleringer, 1984; Bowes, 1993). Possibly, this assumption appeared
1. Plants and their unexpected response to environmental pollution
in the anatomical and functional variation of C3 and C4 plant species and higher CO2 levels in bundle sheath cells of C4 leaves. However, it has been also observed that the variation between C3 and C4 is not as important as anticipated and that C4 plants can also accelerate photosynthesis under elevated CO2. For example, Ziska and Bunce (1997) reported an increase in growth (3%–25%) and photosynthesis (4%–30%) in six different weed species namely, Amaranthus retrofexus, Echinochloa crus-galli, Panicum dichotomiforum, Setariafaberi, Setariaviridis, and Sorghum halapense; and also, inf our crop species namely, Amaranthus hypochondriacus, Saccharum offcinarum, Sorghum bicolor, and Zea mays under elevated CO2.
In some investigations, under abiotic stress (high temperature and drought) conditions it has been noticed that the elevated CO2 reduces the negative effects of stress by mitigating oxidative stress and improving water status in Arabidopsis thaliana (Abo Gamar et al., 2019). Balasooriya et al. (2020) has demonstrated that elevated CO2 (950 ppm) and higher temperature (30°C) increased the amounts of accessible bioactive compounds in strawberries plants. It has been also reported that the rice seed priming with salicylic acid (25 mg L 1) and ascorbic acid (100 mg L 1) increased germination rate, other seed quality features, α-amylase activity, and antioxidant enzyme activities under stress due to elevated CO2 and temperatures (Nedunchezhiyan et al., 2020).
Medicinal plants are good sources for plant secondary metabolites; they hold significant plasticity to acclimatize to the changing environments (Husen, 2021a,b, 2022). Digitalis lanata is known for its use in heart failures (Rahimtoola, 2004), when treated with elevated CO2, there was a 3.5-folds increase in digoxin, a cardenolide glycoside. The digoxin also enhances other three glycosides viz. digoxin-mono-digitoxoside, digitoxin, and digitoxigenin showing a decline in their concentration (Stuhlfauth et al., 1987). It was observed in an experiment on Hymenocallis littoralis whose bulbs are known for their antineoplastic and antiviral properties, the elevated CO2 resulted in an increase in three types of alkaloids (Pancratistatin, 7-deoxynarciclasine, and 7-deoxy-trans dihydronarciclasin) in the first year and decrease in their concentration for the subsequent year (Idso et al., 2000). Similarly, in Ginkgo biloba a traditional Chinese medicinal plant used in Alzheimer’s disease, vascular or mixed dementia (Weinmann et al., 2010) elevated CO2 and O3 together resulted in altered terpenoid content, increase in quercetin aglycon, and decrease in keampferol aglycon (Huang et al., 2010). In Zingiber officinale, elevated CO2 increased flavonoid and phenolic content (Ghasemzadeh et al., 2010). Many explanations and findings related to the aforementioned subject are discussed in Chapter 3.
3. Plant response to photochemical oxidants
The most important photochemical oxidants in the atmosphere include NO2, O3, and PAN. These oxidants are secondary pollutants that develop as a result of sunlight reacting with the products of fuel combustion. O3 is come down from the stratosphere by vertical winds or formed during electrical storms; more importantly, it is produced when sunlight reacts with nitrogen oxides and hydrocarbons formed by refuse burning and combustion of coal or petroleum fuels, especially the exhaust gases from internal-combustion engines. O3 is well known for its life-protective layer against ultra violet radiations. However, the ground level of O3 is increasing because of the rise in O3 precursor emissions in polluted areas. Plant performance
under elevated O3 has been reported by many investigators (Rai and Agrawal, 2012; Fuhrer et al., 2016; Jolivet et al., 2016; Li et al., 2017; Yendrek et al., 2017; Mills et al., 2018; Shang et al., 2019; Peng et al., 2019; Ghosh et al., 2020; Mohamed et al., 2021; Deepti et al., 2022a; Yin et al., 2022). They have shown that the young plants are generally the most sensitive to O3 whereas mature plants are relatively resistant.
O3 is most likely an important plant-toxic air pollutant and a very active form of oxygen that causes different types of symptoms on broad-leaved plants such as interveinal chlorosis, necrosis, scar on the upper surface of leaves, tissue collapse, flecking, bleaching, and mottling. O3 reduced the plant growth and slow down bud formation and flowering. Affected leaves of certain plants, such as tobacco, citrus, and grape shrink and drop early. Conifers recurrently express a yellow to brown mottling and tip burn, or flecking and banding of the needles (Stolte, 1996). The flecks may later combine to form larger, bleached white to yellowish dead areas. O3 usually attacks nearly mature leaves first, moving to younger and older leaves. The leaves tissues damaged by O3 are infected by certain fungi like Botrytis. O3 has several biochemical and physiological effects on plants.
At the biochemical level, O3 oxidizes sulfhydryl and fatty acid double bonds, increases membrane permeability, disrupts membrane-bound photosynthetic systems, and reduces foliar sugar and polysaccharide levels. At the physiological level, stomatal conductance, net photosynthesis, and water use efficiency are reduced, dark respiration is affected, carbon allocation is changed, leaf senescence is accelerated, foliar visible injuries and leaching are increased, floral yield is decreased, and fruit set is delayed. O3-induced reduction in growth rates and yield happens through impaired net photosynthesis and regeneration (Rai and Agrawal, 2012; Deepti et al., 2022a). O3 impacts changes in wood quality reduced wood density and tracheid length, resulting in reductions in wood strength, pulp yield, and quality. The oxidation products of atmospheric nitrogen (NOx) are chemically reactive gaseous pollutants with harmful effects on biological systems. NO2 is a precursor molecule for other NOx components and O3 (Chappelka and Samuelson, 1998). A reduction in the level of RNA transcript for the small subunit of RuBisCO, photosynthetic gene expression under ozone stress has been reported in rice plants (Agrawal et al., 2002).
In another report, Sarkar and Agrawal (2010) also reported reduced levels of mRNA (both small and large subunits of RuBisCO) in the same plant under ozone exposure. In an experiment, Ghosh et al. (2020) used two sowing dates (timely sown and late sown) to explore the effect of elevated O3 on Triticum aestivum cv. HD 2967 growth including biomass, leaf gas exchange rate and other yield features such as the length of the ear plant, weight of ears plant, number of grains plant, weight of grains plant, husk weight plant, straw weight plant, harvest index, test weight of the grains, and straw grain ratio. Ghosh et al. (2020) concluded that O3 stress affected growth and productivity and late sowing practice is not worthwhile for wheat cultivation. Many other investigations have exhibited that O3 stress adversely influences photosynthesis and other related physiological performance in wheat (Feng et al., 2008; Ghosh et al., 2020), soybean (Morgan et al., 2003), rice (Ainsworth, 2008), radish, and brinjal (Tiwari and Agrawal, 2011). The reduced rate of assimilation was attributed to decreased carboxylation efficiency and was associated with reduced RuBisCO activity (Leitao et al., 2007).
Sarkar and Agrawal (2010) reported that the degree of O3-induced foliar injury depends on the exposure duration and concentration. Reduced photosynthesis may also be noticed because of damage to thylakoids, which influenced photosynthetic transport of electrons and is
