Advances in Plant Nitrogen Metabolism

Cover
Half Title
Title Page
Copyright Page
Table of Contents
Foreword
Preface
About the Editors
Contributors
1 Introduction to Plant Nitrogen Metabolism: An Overview
1.1 Introduction
1.2 Nitrogen, Its Occurrence, Importance, and Role in Plants: An Overview
1.3 Nitrogen Deficiency in Plants
1.4 Nitrogen Assimilation in Plants
1.4.1 Nitrate Reductase Converts Nitrate to Nitrite
1.4.2 Nitrite Reductase Converts Nitrite to Ammonium
1.4.3 Nitrogen Uptake and Transport in Plants: Pathways, Transporters, Etc.
1.5 Regulatory RNAs and Their Role in Nitrogen Metabolism
1.6 Role Of Nitrogen in Photosynthesis
1.7 Recycling and Remobilization of Nitrogen During Senescence
1.8 Role of Phytohormones in Nitrogen Metabolism
1.9 Regulation of Nitrogen Metabolism Under Abiotic Stress
1.9.1 Nitrogen Metabolism Under Drought Stress
1.9.2 Nitrogen Metabolism Under High-Temperature Stress
1.9.3 Nitrogen Metabolism Under Salinity Stress
1.9.4 Nitrogen Metabolism Under Heavy Metal Stress
1.10 Epigenetic Regulation of Nitrogen Metabolism
1.11 Omics Approaches to Nitrogen Metabolism in Plants
1.12 Reactive Nitrogen Species (RNS) in Plants
1.13 Nitrogen Use Efficiency in Plants: Physiological and Molecular Aspects
1.14 Nitrogen Toxicity in Plants, Symptoms and Safeguards
1.15 Biological Nitrogen Fixation: An Overview
1.16 Nitrogenase Enzyme Complex
1.17 Nod, Nif, and Fix Genes
1.18 Biochemical and Functional Aspects of Legume Nodule
1.18.1 Synthesis, Transport, and Assimilation of Products of Symbiotic Nitrogen Fixation
1.19 Nitrogen Biofertilizers: Role in Sustainable Agriculture
References
2 Nitrogen: A Key Macronutrient for the Plant World
2.1 Introduction
2.2 Discovery
2.3 Chemistry and Structure of Nitrogen
2.3.1 Electronic Configuration
2.3.2 Lewis Structure
2.3.3 Physical And Chemical Properties
2.3.3.1 Physical Properties
2.3.3.2 Chemical Properties
2.3.4 Isotopes of Nitrogen
2.4 Occurrence and Sources of Nitrogen
2.5 Role of Nitrogen in Plants
2.6 Factors Affecting Nitrogen Nutrition
2.6.1 Soil PH
2.6.2 Soil Fertility
2.6.3 Soil Texture
2.6.4 Soil Moisture
2.7 Deficiency Symptoms of Nitrogen
2.8 Effects of Excessive Nitrogen
2.8.1 Increased Foliage Growth
2.8.2 Stunted Root Growth
2.8.3 Underground Water Pollution
References
3 Nitrogen Deficiency in Plants
3.1 Introduction
3.2 Diagnosis of Nitrogen Deficiency in Plants
3.3 Effect of Nitrogen Deficiency On Plant Growth and Development
3.4 Efficiency of Plants to Use Nitrogen
3.5 Nitrogen Management Practices
3.5.1 Method of Broadcasting
3.5.2 Placement Method
3.5.3 Starter Approach Application
3.5.4 Foliar Application
3.5.5 Fertigation Technique
3.6 Conclusion
References
4 Nitrogen Assimilation in Plants
4.1 Nitrogen in the Environment
4.2 Nitrogen – An Important Element for Plant Growth
4.2.1 Nitrogen Fixation
4.2.2 Ammonification
4.2.3 Nitrification
4.2.4 Denitrification
4.2.5 Nitrogen Assimilation in Plants
4.3 Nitrogen Uptake in Plants
4.3.1 Role of Phloem in Amino Acid Translocation
4.3.2 Reduction of Nitrate to NH₃
4.3.3 Fixation of NH₄⁺
4.4 Enzymes Responsible for Nitrogen Assimilation
4.4.1 Nitrate Reductase (NR)
4.4.2 Nitrite Reductase (NIR)
4.5 Factors Affecting Nitrogen Absorption and Assimilation
4.5.1 Soil Parameters
4.5.1.1 Soil PH
4.5.1.2 Soil Salinity and Fertility
4.5.2 Climate
4.5.3 Metals
4.5.4 Ultraviolet B Radiation
4.5.5 Gaseous Factors
4.5.6 Nutritional Factors
4.5.7 Environmental Factors
4.5.8 Other Factors
4.6 Conclusion
References
5 Assimilation of Nitrates in Plants
5.1 Introduction
5.2 Nitrate Assimilation
5.3 Nitrate Uptake
5.4 Enzymes Involved in Nitrate Assimilation
5.4.1 Nitrate Reductase
5.4.1.1 Subunits
5.4.2 Nitrite Reductase
5.5 Regulation of Nitrate Transport and Reduction
5.6 Ammonium Assimilation
5.6.1 Glutamine Synthetase (GS)
5.6.2 Glutamate Synthase
5.6.3 Glutamate Dehydrogenase
5.7 Fixed Nitrogen Is Exported as Asparagine and Ureides
5.8 Conclusion
References
6 Factors Affecting Nitrogen Uptake, Transport, and Assimilation
6.1 Introduction
6.2 Nitrogen Uptake and Transport
6.2.1 Forms of Nitrogen
6.2.2 Nitrogen Uptake Sites
6.2.3 Nitrogen Uptake Rates
6.2.4 Transport
6.3 Factors Affecting Uptake and Transport Of Nitrogen
6.3.1 Nitrate Uptake Repression By Ammonium
6.3.2 Rhizosphere PH
6.3.3 Interactions Among Ions
6.3.4 Supply of Photosynthates
6.3.5 Temperature
6.3.6 Mycorrhizal Associations
6.4 Nitrogen Assimilation
6.5 Factors Affecting Assimilation
6.5.1 Nitrogen Levels
6.5.2 Ultraviolet B Radiation
6.5.3 Gaseous Factors
6.5.4 Soil Salinity
6.5.5 Metals
6.6 Conclusion
References
7 Role of Nitrogen in Photosynthesis
7.1 Introduction
7.2 Role of Nitrogen to Scale Up Photosynthesis
7.3 Molecular Approach
7.4 Conclusion
Acknowledgments
References
8 Recycling and Remobilization of Nitrogen During Senescence
8.1 Introduction
8.2 Internal Redistribution of Nitrogen During the Plant’s Life Cycle
8.3 Protein Degradation Is Universal to N Remobilization
8.4 The Chloroplast Degradation Pathway
8.4.1 Degradation of the Stromal Proteins
8.4.2 Degradation of Thylakoid-Bound Proteins
8.5 The Ubiquitin/Proteosome Pathway
8.6 Autophagic and Vacuolar Pathway of Protein Degradation
8.7 Remobilization of Nitrogenous Compounds
8.7.1 The GS/GOGAT Pathway
8.7.2 The PPDK-GS/GOGAT Pathway
8.8 Translocation of Nitrogen Compounds to the Sink Tissues
8.9 Targets to Improve Nitrogen Fertilization
8.10 Conclusion
References
9 Role of Phytohormones in Nitrogen Metabolism
9.1 Introduction
9.2 Phytohormones and Nitrogen Regulation
9.2.1 Auxin
9.2.2 Cytokinin
9.2.2.1 Nitrate Uptake Regulation Through Cytokinin
9.2.3 Abscisic Acid
9.2.4 Ethylene
9.2.4 Jasmonic Acid
9.3 Conclusion
References
10 Biological Nitrogen Fixation: An Overview
10.1 Introduction
10.2 Microbiology Involved in Nitrogen Fixation
10.3 Process of Biological Nitrogen Fixation
10.4 Genetic Regulation of Biological Nitrogen Fixation
10.5 Role of Flavonoids in Biological Nitrogen Fixation
10.5.1 Expression of Nod Genes
10.5.2 Regulation of Genes Involved in the T3SS Strategy
10.5.3 Growth Stimulants and Chemoattractants for Rhizobium Spp.
10.5.4 Act as Phytoalexins During Nodulation
10.5.5 Nitrogen Fixation of Actinorhizal Plant
10.5.6 Establishment of Actinorhizal Symbioses
10.5.7 Host Specificity
10.5.8 Development and Function Of Nodule
10.5.9 The Prospective of Manipulating Flavonoids
10.6 Role of Mineral Nutrients in Biological Nitrogen Fixation
10.7 Conclusion
References
11 Nitrogenase Enzyme Complex: Functions, Regulation, and Biotechnological Applications
11.1 Introduction
11.2 Functions of Nitrogenase
11.3 Nitrogenase Regulation
11.3.1 ADP Ribosylation
11.3.2 Nif Genes
11.3.3 Environmental Signals
11.3.4 Post-Translation Control
11.4 Biotechnological Application of Nitrogenase
11.4.1 Enzymatic Bioelectrocatalysis
11.4.2 Engineering Biological Nitrogen Fixation
11.5 Way Forward
References
12 Nod, Nif, and Fix Genes
12.1 Introduction
12.2 Nitrogen Fixation Process
12.3 Location of SNF Genes
12.3.1 Nod Genes
12.3.2 Nif Genes
12.3.3 Fix Genes
12.4 Conclusion
References
13 Nitrogen Biofertilizers: Role in Sustainable Agriculture
13.1 Introduction
13.2 Nitrogen Biofertilizers: Why Their Need Is Inevitable
13.3 Nitrogen-Fixing Biofertilizers
13.3.1 Rhizobium
13.3.2 Azospirillum
13.3.3 Azotobacter
13.3.4 Blue-Green Algae (Cyanobacteria) and Azolla
13.3.5 Nitrogen-Fixing Endophytes
13.4 Different Methods of Application of Biofertilizers to Crops
13.4.1 Seedling Root Dip
13.4.2 Seed Treatment
13.4.3 Soil Treatment
13.4.4 Use of Vam Biofertilizer
13.4.5 Use of Blue-Green Algae (BGA)
13.5 The Nitrogen Fixation Process
13.6 Molecular Analysis Of Nitrogen Fixation
13.7 Symbiotic Nitrogen Fixation
13.8 Potential Role of Biofertilizers in Agriculture
13.9 Nitrogen Biofertilizers: Environmental Stresses
13.9.1 Constraints in Biofertilizer Use
13.10 Conclusion
Acknowledgments
References
14 Effect of Biotic Stresses On Plant Nitrogen Metabolism
14.1 Introduction
14.2 Action of Different Biotic Agents
14.3 Defense Responses
14.4 Physiological and Molecular Changes
References
15 Salt Stress and Nitrogen Metabolism in Plants
15.1 Introduction
15.2 Salt Stress Impedes Plant Growth and Development
15.3 Cellular Effects of Salinity
15.3.1 Osmotically Induced Water Stress
15.3.2 Specific Ion Stress
15.3.3 Oxidative Stress
15.3.4 Nutritional Imbalance Stress
15.4 Effect of Salt Stress On Nitrogen Metabolism
15.4.1 Effect of Salt Stress On Nitrogen Uptake
15.4.2 Effect of Salt Stress On No₃^- Assimilation
15.4.3 Effect of Salt Stress On NH₄⁺ Assimilation
15.5 Conclusion
References
16 Reactive Nitrogen Species in Plants
16.1 Introduction
16.2 Source of RNS in Plants
16.2.1 Nitric Oxide (NO)
16.2.2 Peroxynitrite (OONO^-)
16.2.3 Nitrosothiols
16.3 Conclusion and Future Outlook
References
17 Nitrogen Toxicity in Plants, Symptoms, and Safeguards
17.1 Introduction
17.2 Nitrogen Deficiencies
17.3 Nitrogen Toxicity
17.3.1 Toxicity of Excess N
17.4 Toxic Effects of Different Nitrogen Forms On Plants
17.4.1 NH₄⁺ Toxicity
17.4.1.1 Effects of NH₄⁺ On Plant Development
17.4.1.2 Biochemical and Physiological Changes During NH₄⁺ Toxicity
17.4.2 NO2- Toxicity
17.4.3 N03 Toxicity
17.5 Alleviation of NH₄⁺ Toxicity
References
18 Nitrogen Metabolism Enzymes: Structure, Role, and Regulation
18.1 Introduction
18.2 Nitrate Reductase (NR)
18.2.1 Structure
18.2.2 Classes of NR
18.3 Environmental Factors Regulating Nitrate Reductase Enzyme
18.3.1 Light and Photosynthesis
18.3.2 Response of Leaf NR Activation to Nitrate Supply
18.3.3 Modulation of NR in Roots: Response to Anoxia
18.3.4 Response of NR to Salt Stress
18.3.5 Response of NR to Water Stress
18.4 Glutamine Synthetase
18.4.1 Structure of Glutamine Synthetase
18.4.2 Factors Affecting the Activity of Glutamine Synthetase
18.4.2.1 Light
18.4.2.2 Nitrogen and Carbon Concentration
18.4.2.3 Metabolites
18.5 Glutamate Synthase
18.5.1 Structure
18.5.2 External Factors Affecting GOGAT
18.5.2.1 LIGHT
18.5.2.2 Temperature
18.5.2.3 Salinity Stress
18.5.2.4 Water
References
19 Regulatory RNAs and Their Role in Nitrogen Metabolism of Diazotrophs
19.1 Introduction
19.2 Role of SRNAs in Nitrogen Metabolism
19.2.1 Indirect Involvement of sRNAs in Nitrogen Metabolism
19.2.1.1 Role of sRNAs in Cyanobacteria
19.2.1.2 Role of sRNAS in Gammaproteobacteria
19.2.1.3 Role of sRNA in Alphaproteobacteria
19.2.1.4 Role of sRNA in Methanoarchae
19.2.2 Direct Involvement of SRNAs in Nitrogen Metabolism
19.2.2.1 sRNA NSiR4 in Synechocystis 6803
19.2.2.2 sRNA NfiS in Pseudomonas Stutzeri A1501
19.2.2.3 sRNA₁₅₄ in M. Mazei Strain Gö1
19.3 Can Regulatory RNA Sense Nitrogen Status?
19.4 Conclusion
References
Index