Approaches for Enhancing Abiotic Stress Tolerance in Plants

Mirza Hasanuzzaman, Kamrun Nahar, Masayuki Fujita, Hirosuke Oku, Tofazzal Islam

• Publisher: CRC Press
• Year: 2019
• eBook ISBN: 9781351104708
• Edition: 1
• Topic: Biological Sciences
• Subtopic: Biology
• Index: Biological Sciences

Plants are frequently exposed to unfavorable and adverse environmental conditions known as abiotic stressors. These factors can include salinity, drought, heat, cold, flooding, heavy metals, and UV radiation which pose serious threats to the sustainability of crop yields. Since abiotic stresses are major constraints for crop production, finding the approaches to enhance stress tolerance is crucial to increase crop production and increase food security. This book discusses approaches to enhance abiotic stress tolerance in crop plants on a global scale. Plants scientists and breeders will learn how to further mitigate plant responses and develop new crop varieties for the changing climate.

1	Abiotic Stress in Plants

A General OutlineAshutosh K. Pandey, Annesha Ghosh, Kshama Rai, Adeeb Fatima, Madhoolika Agrawal, and S.B. Agrawal

CONTENTS

1.1 Introduction

1.2 Soil Salinity Stress

1.2.1 Effect of Soil Salinity on Growth and Yield

1.2.2 Effect of Soil Salinity on Plant Physiology

1.2.3 Antioxidants Activity under Soil Salinity

1.2.4 Signaling and Its Significance in Alleviating Salt Stress in Plants

1.3 Drought

1.3.1 Morphological Responses to Drought Stress

1.3.2 Physiological Responses of Plants

1.3.3 Antioxidant Metabolism under Drought Stress

1.3.4 Yield Attributes under Drought Condition

1.3.5 Signaling and Drought Stress

1.4 Metal Toxicity

1.4.1 Defense Strategies Adopted by the Plant in Response to Heavy Metal Stress

1.4.2 Antioxidants Activity under Metal Toxicity

1.4.3 Zn Metal Transporters

1.4.4 Fe Transporter

1.4.5 Al Transporters

1.5 Flooding Stress

1.5.1 Morphological and Anatomical Responses

1.5.2 Physiological Adaptation

1.5.3 Antioxidative Response and Signaling Cascades under Flooding Condition

1.6 Radiation—A Potent Abiotic Stress

1.6.1 Ultraviolet Radiation

1.6.2 Morphological, Physiological and Biochemical Changes

1.6.3 Biochemical Response against UV-B

1.6.4 Antioxidative Defense in Response to UV-B

1.6.5 Signal Transduction

1.6.6 Yield responses to UV-B radiation

1.7 Temperature Stress

1.7.1 Plant Responses to Heat Stress

1.7.2 HSPs as Molecular Chaperons

1.7.3 Cold Stress

1.7.4 Antioxidative Response and Signaling Cascade under Cold Stress

1.8 Stress Caused by Various Air Pollutants

1.8.1 Tropospheric Ozone

1.8.1.1 Formation of O₃

1.8.1.2 Growth and Yield Attributes due to O₃ Stress

1.8.1.3 Physiological Response due to O₃ Stress

1.8.1.4 Antioxidative and ROS Signaling During O₃ Stress

1.8.2 Sulfur Dioxide (SO₂)

1.8.3 Oxides of Nitrogen (NOx)

1.8.4 Volatile Organic Compounds (VOCs)

1.8.4.1 Role of VOCs in Plant Metabolism and Defense

1.9 Conclusions

Acknowledgments

References

1.1 Introduction

Plants encounter several abiotic stresses which are the major constraints to plant growth and productivity, causing extensive crop losses linked to food security across the world (Mittler, 2006). Plants have to exploit their immediate environment to maximum effect to cope up with the challenging adverse abiotic stresses. Plants have developed unique characteristics to defend themselves via modulating their phenotypes with physiological, biochemical, molecular changes, thereby strengthening their stress tolerance mechanisms for survival (Mohanta et al., 2017). Apparently, the most widely studied linear signaling pathways are actually a part of a more complicated signaling web network comprising overlapping between its web branches, resulting in induction of genes by more than one particular abiotic stress.

World population is rising at an alarming rate and is likely to attain about 9.8 billion by the end of the year 2050. On the contrary, agricultural productivity is not increasing at a requisite rate to keep up the pace with increasing food demand. The major abiotic stress factors posing serious threats to the agriculture and environment are drought, flooding, radiation (UV-B) soil salinity, extreme temperatures, heavy metal toxicity and numerous air pollutants that are pumped into the atmosphere at an alarming rate since the preindustrial times. Due to rising concentrations of CO₂ and other atmospheric trace gases, global temperatures have increased by about 1°C over the course of the last century and will likely rise even more in coming decades as reported by the Intergovernmental Panel on Climate Change (IPCC, 2014). Increased drought and salinization of arable land are expected to have devastating global effects on crop production (Wang et al., 2003).

The anthropogenically induced depletion of the stratospheric ozone layer is adding two more potential abiotic stresses, i.e., UV-B radiation and high light. Various model studies have suggested that the continuous rate of stratospheric ozone layer depletion would increase the penetration of UV-B by 9% (McKenzie et al., 2007). In 2015, a report from NASA suggested that due to the successful implementation of the Montreal Protocol (1987), the stratospheric ozone hole is recovering, but it will take a large time up to 2075 for its full recovery (NASA, 2015). The equatorial region of the globe is more prone to high temperature and intense UV-B perceptions due to a thinner layer of ozone in the stratosphere. Similarly, the major driving factor behind most of the abiotic stresses is the anthropogenic misuse of natural resources, heavy industrial activities, intense vehicular traffic and so on, and these factors are loading the atmosphere with tons of air pollutants (primary and secondary) ranging from oxides of sulfur (Sox), oxides of nitrogen (Nox), tropospheric ozone (O₃) and volatile organic compounds (VOCs) .

Here, we review plant responses to different abiotic stresses at cellular, morphological, physiological, biochemical and molecular levels. We have emphasized different antioxidative mechanisms and signaling transduction cascades generated in response to a particular stimulus to develop a better understanding of adaptive mechanisms operating in the plants. In the light of abiotic-stress-induced phytotoxicity, this compilation could be useful to the plant breeders in screening the cultivars and also in developing tolerant varieties depending on different stress-response relationships.

1.2 Soil Salinity Stress

Soil salinity has been a hazard to agriculture in some parts of the world for over 3000 years; in recent times, the threat has further pronounced to a larger area (Flowers, 2006). Soil salinization is a major factor contributing to the loss of productivity of cultivated soils. The area of salinized soils is increasing, and this phenomenon is particularly severe in irrigated soils. It was estimated that about 20% (45 million ha) of irrigated land, producing one-third of the world’s food, is salt-affected (Shrivastava and Kumar, 2015). Globally, soil salinization is more common in arid and semi-arid regions than in humid regions. The amount of world agricultural land destroyed by salt accumulation is estimated to be 10 million ha (Pimentel et al., 2004) each year. This rate can be accelerated by climate change, excessive use of groundwater (mainly coastal area), increasing use of low-quality water in irrigation and massive introduction of irrigation associated with intensive farming and poor drainage. The use of low-quality water for irrigation can lead to the accumulation of salts in the soil, since the leaching fraction is reduced and the salts contained in the irrigation water are not leached enough. It is estimated that, by 2050, 50% of the world’s arable land will be affected by salinity (Bartels and Sunkar, 2005).

1.2.1 Effect of Soil Salinity on Growth and Yield

Soil salinity reduces the productivity of many crops which have a low tolerance to soil salinity. The first morphological symptoms of salt stress are wilting, yellowing of leaves and stunted growth. In a second phase, the damage manifests as chlorosis of green parts, leaf tip burning, necrosis of leaves, and the oldest leaves display scorching (Shannon and Grieve, 1998). Although plant species differ in their sensitivity or tolerance to salts (Marschner, 1995), high soil salinity has detrimental effects on seed germination and plant growth (Taiz and Zeiger, 2006) and in due course kills growing plants (Garg and Gupta, 1997).

The salt-induced water deficit and many nutrient interactions in salt-stressed plants are the major constraints for plant growth in saline soils. Indeed, salinity effects on plant growth reduction are a time-dependent process, and Munns et al. (1995) proposed a two-phase model to depict the response of plant growth to salinity. The first phase is very rapid, and growth reduction is ascribed to the development of a water deficit. The second phase is due to the accumulation of salts in the shoot at toxic levels and is very slow. The presence of high concentrations of sodium, calcium and magnesium causes damage to soil structure and is accompanied by an increase in the compactness of soils with a decrease in filterability, hydraulic conductivity and the oxygen availability in the root zone. Another effect of a high concentration of sodium is an increase of alkalization. Excess sodium (Na⁺) in the soil competes with Ca²⁺, K⁺ and other cations to reduce their availability to crops. Therefore, soils with high levels of exchangeable sodium (Na⁺) may impact plant growth by dispersion of soil particles, nutrient deficiencies or imbalances and specific toxicity to sodium sensitive plants. Salini...

Table of contents

• Cover
• Half-Title
• Title
• Copyright
• Contents
• Preface
• Editors
• Contributors
• Chapter 1 Abiotic Stress in Plants
• Chapter 2 Impacts of Climate Change on Crop Production, with Special Reference to Southeast Asia
• Chapter 3 Plant Responses and Tolerance to Salt Stress
• Chapter 4 Plant Responses and Tolerance to Drought
• Chapter 5 Plants Signaling toward Drought Stress
• Chapter 6 Variability in Physiological, Biochemical, and Molecular Mechanisms of Chickpea Varieties to Water Stress
• Chapter 7 Plant Responses and Mechanisms of Tolerance to Cold Stress
• Chapter 8 Unraveling the Molecular and Biochemical Mechanisms of Cold Stress Tolerance in Rice
• Chapter 9 Heavy Metal Toxicity in Plants and Its Mitigation
• Chapter 10 Nutrient Deficiency and Toxicity Stress in Crop Plants
• Chapter 11 Plant Responses to Ozone Stress
• Chapter 12 Hydrocarbon Contamination in Soil and Its Amelioration
• Chapter 13 Abiotic Stress-Mediated Oxidative Damage in Plants
• Chapter 14 Plant Antioxidant Response During Abiotic Stress
• Chapter 15 Approaches to Enhance Antioxidant Defense in Plants
• Chapter 16 Coordination and Auto-Propagation of ROS Signaling in Plants
• Chapter 17 Regulation of Osmolytes Syntheses and Improvement of Abiotic Stress Tolerance in Plants
• Chapter 18 The Role of Plasma Membrane Proteins in Tolerance of Dehydration in the Plant Cell
• Chapter 19 Trehalose Metabolism in Plants under Abiotic Stresses
• Chapter 20 The Proline Metabolism of Durum Wheat Dehydrin Transgenic Context and Salt Tolerance Acquisition in Arabidopsis thaliana
• Chapter 21 Nitric Oxide-Induced Tolerance in Plants under Adverse Environmental Conditions
• Chapter 22 Molecular Mechanisms of Polyamines-Induced Abiotic Stress Tolerance in Plants
• Chapter 23 Molecular Approaches for Enhancing Abiotic Stress Tolerance in Plants
• Chapter 24 Genomic Approaches for Understanding Abiotic Stress Tolerance in Plants
• Chapter 25 Hallmark Attributes of Plant Transcription Factors and Potentials of WRKY, MYB and NAC in Abiotic Stresses
• Chapter 26 Application of CRISPR-Cas Genome Editing Tools for the Improvement of Plant Abiotic Stress Tolerance
• Chapter 27 Beneficial Microorganisms and Abiotic Stress Tolerance in Plants
• Index