Photosynthesis, Productivity, and Environmental Stress

Parvaiz Ahmad, Mohammad Abass Ahanger, Mohammed Nasser Alyemeni, Pravej Alam, Parvaiz Ahmad, Mohammad Abass Ahanger, Mohammed Nasser Alyemeni, Pravej Alam

• Publisher: Wiley-Blackwell
• Year: 2019
• Print ISBN: 9781119501770
• eBook ISBN: 9781119501824
• Edition: 1
• Topic: Biological Sciences
• Subtopic: Botany
• Index: Biological Sciences

A guide to environmental fluctuations that examines photosynthesis under both controlled and stressed conditions

Photosynthesis, Productivity and Environmental Stress is a much-needed guide that explores the topics related to photosynthesis (both terrestrial and aquatic) and puts the focus on the basic effect of environmental fluctuations. The authors—noted experts on the topic—discuss photosynthesisunder both controlled and stressed conditions and review new techniques for mitigating stressors including methods such as transgeneics, proteomics, genomics, ionomics, metabolomics, micromics, and more.

In order to feed our burgeoning world population, it is vital that we must increase food production. Photosynthesis is directly related to plant growth and crop production and any fluctuation in the photosynthetic activity imposes great threat to crop productivity. Due to the environmental fluctuations plants are often exposed to the different environmental stresses that cause decreased photosynthetic rate and problems in the plant growth and development. This important book addresses this topic and:

• Covers topics related to terrestrial and aquatic photosynthesis
• Highlights the basic effect of environmental fluctuations
• Explores common stressors such as drought, salinity, alkalinity, temperature, UV-radiations, oxygen deficiency, and more
• Contains methods and techniques for improving photosynthetic efficiency for greater crop yield

Written for biologists and environmentalists, Photosynthesis, Productivity and Environmental Stress offers an overview of the stressors affecting photosynthesis and includes possible solutions for improved crop production.

1
Effects of Organic Pollutants on Photosynthesis

Rupal Singh Tomar ¹, Bhupendra Singh ¹, and Anjana Jajoo ^1,2

¹ School of Life Science, Devi Ahilya University, Indore, Madhya Pradesh, India

² School of Biotechnology, Devi Ahilya University, Indore, Madhya Pradesh, India

1.1 Introduction to Organic Pollutants

Life on earth is powered by the process of photosynthesis. For more than billion years, life on earth has been transformed by the photosynthetic organisms. Photosynthetic organisms like cyanobacteria, algae, and plants harvest sunlight and produce oxygen and organic molecules, which are responsible for life on earth. Photosynthesis starts with the absorption of light of the visible region coming from the sun. It includes several partial processes such as splitting of water to molecular oxygen, electrons, and protons, which participate directly in the electrochemical reactions leading to phosphorylation and fixation of carbon dioxide into sugars.

Plants are sessile organisms that cannot move and thus cannot avoid exposure to fluctuating environmental conditions. Plants face several abiotic stress factors, such as water deficit (drought), excess water (flooding/water logging), extremes of temperatures (cold, chilling, frost, heat), high salt, mineral deficiency, and toxicity. Because of climate changes, it is predicted that these abiotic stresses may become more intense and frequent. Climate change, occurring either naturally or anthropogenically, poses serious challenges for agriculture all over the world.

During the last decades, environmental contamination has become one of the major problems on this planet. Anthropogenic activities have led to an abundance of soil, water, and air pollutants, factors that directly affect plants. Amongst these, environmental organic pollutants (OPs) have an immense effect on plant growth and development. OPs and their transformation products have been the most investigated environmental pollutants in last two decades. They accumulate in humans, animals, and plants as they are hydrophobic and lipid‐soluble, and they biomagnify as they move up the food chain. OPs can be found everywhere on earth as they can travel great distances in both air and water. OPs have been found to cause serious disorders in mammals such as cancer and endocrine disorders. It is therefore essential to understand how these contaminants enter and move in the ecosystem and environment. Plants are capable of taking up, transforming, and accumulating environmental pollutants such as OPs. Several physiological and biochemical reactions in plants are influenced by OPs in the same way as other toxic compounds such as metals. They can change the energetic metabolism of plants and are associated with growth and development. About 90% of the OPs accumulate in the soil due to their hydrophobic nature, because of which they rapidly associate with solid particles of soil and permeate to bottom sediments. Several studies have been carried out on the uptake of OPs by plants and their toxicity to plants cells. Here we present an updated account of these studies, focusing on (i) the uptake of OPs by the plants and (ii) their harmful effects on the photosynthetic reactions.

The rapid growth in chemical and agrochemical industries has resulted in the release of a large number of new and toxic chemical compounds into the environment. These OPs are getting significant attention in environmental and engineering research. Several countries and international organizations have published lists of harmful pollutants, which are at alarming levels and should be controlled immediately. The group of organic chemicals discussed here include the pesticides, antibiotics, bisphenol A (BPA) and polycyclic aromatic hydrocarbons (PAHs) (Figure 1.1). Several internal and external factors regulate normal development and productivity of plants. External factors include natural and man‐made chemicals that have detrimental effects on plants. OPs are a major threat in terrestrial as well as aquatic ecosystems. They quite easily cross the cell membrane of plant and animal cells due to their lipophilic character resulting in substantial bioconcentration. Plant roots and leaves serve as a major sink for these pollutants. Plants and bacteria are both involved in the biogeochemical cycling of OPs. Uptake of OPs depends on cell size, temperature, and their hydrophobicity (Dachs et al. 2002; Gang and Xitao 2005). The toxic effect of OPs may be a result of direct interaction, or some OPs may accumulate into the plant tissue to a toxic level and can affect the plant development at any stage (Hanano et al. 2015). OPs contaminate water, soil, and sediments and thus become a major environmental problem that needs to be rectified. In more recent years, the studies with these OPs are more focused on the characterization of toxicity response in a variety of plant and animal species. Scientists are also trying to explore some plants species to degrade or at least to detoxify (phytoremediation) these OPs to protect other organisms from the adverse effects of these compounds.

Figure 1.1 Broad classification of organic pollutants (OPs), based on their effects on plants and photosynthetic machinery.

1.2 Characteristics of the Organic Pollutants

All OPs are synthetic chemicals, many are pesticides, while some others are products or by‐products of industrial processes or of incomplete combustion. They are quite persistence in the environment, and it may take a long time, up to several decades or even centuries, for their degradation. OPs have been found in tissues or environmental samples from almost all parts of the world. They are lipophilic in nature and have a tendency to remain in lipid‐rich tissues. This affinity for the fat tissues suggests that most likely, OPs will accumulate, persist, and bioconcentrate, and eventually could reach toxicologically significant amounts. In nature, OPs enter the food chain and prove to be toxic to plants, animals, and human beings.

Because of their unique physicochemical characteristics, OPs are either adsorbed on atmospheric particles or exist in the vapor phase, which facilitates their transport over larger distances in the...

Table of contents

• Cover
• Table of Contents
• Copyright
• List of Contributors
• Preface
• About the Editors
• 1 Effects of Organic Pollutants on Photosynthesis
• 2 Cold Stress and Photosynthesis
• 3 High‐Temperature Stress and Photosynthesis Under Pathological Impact
• 4 Effect of Light Intensity on Photosynthesis
• 5 Regulation of Water Status, Chlorophyll Content, Sugar, and Photosynthesis in Maize Under Salinity by Mineral Mobilizing Bacteria
• 6 Regulation of Photosynthesis Under Metal Stress
• 7 Heavy Metals and Photosynthesis: Recent Developments
• 8 Toward Understanding the Regulation of Photosynthesis under Abiotic Stresses: Recent Developments
• 9 Current Understanding of the Regulatory Roles of miRNAs for Enhancing Photosynthesis in Plants Under Environmental Stresses
• 10 Mineral Mobilizing Bacteria Mediated Regulation of Secondary Metabolites for Proper Photosynthesis in Maize Under Stress
• 11 Role of Plant Hormones in Improving Photosynthesis
• 12 Promising Monitoring Techniques for Plant Science: Thermal and Chlorophyll Fluorescence Imaging
• 13 Introgression of C4 Pathway Gene(s) in C3 Plants to Improve Photosynthetic Carbon Assimilation for Crop Improvement: A Biotechnological Approach
• 14 Interaction of Photosynthesis, Productivity, and Environment
• End User License Agreement