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                            Cover
The Chloroplast
	Advances in Photosynthesis and Respiration
		Govindjee, Series Editor
		Thomas D. Sharkey, Co - Series Editor
	The Chloroplast: Basics and Applications
	ISBN 9048185300
	Contents
	Preface
	Contributors
Chapter 1: Investigation of Possible Relationships Between the Chlorophyll Biosynthetic Pathway, the Assembly of Chlorophyll–
	I Introduction
	II Agricultural Productivity and Photosynthetic Efficiency
		A The Primary Photochemical Act of Photosystem I (PS I) I and II
		B Conversion of Carbon Dioxide into Carbohydrates
		C Theoretical Maximal Energy Conversion Efficiency of the Photosynthetic Electron Transport System of Green Plants
		D Actual Energy Conversion Efficiency of the PETS of Green Plants Under Field Conditions
	III Molecular Basis of the Discrepancy Between the Theoretical Maximal Efficiency of the Photosynthetic Electron Transport Cha
		A Contribution of Extrinsic Photosynthetic Electron Transport System Parameters to the Discrepancy between the Theoretical Phot
		B Contribution of Intrinsic Photosynthetic Electron Transport Chain Parameters to the Discrepancy Between the Theoretical Pho
	IV Correction of the Antenna/Photosystem Chlorophyll Mismatch
		A State of the Art in Our Understanding of Chlorophyll Biosynthesis
			1 The Single-Branched Chl Biosynthetic Pathway Does Not Account for the Formation of All the Chlorophyll in Green Plants
			2 The Chlorophyll of Green Plants Is Formed Via a Multibranched Biosynthetic Pathway
		B Thylakoid Apoprotein Biosynthesis
		C Assembly of Chlorophyll–Protein Complexes
			1 Assembly of Chlorophyll–Protein Complexes: The Single-Branched Chlorophyll Biosynthetic Pathway (SBP)-Single Location Model
			2 Assembly of Chlorophyll–Protein Complexes: The Single- Branched Chlorophyll Biosynthetic Pathway-Multilocation Model
			3 Assembly of Chlorophyll–Protein Complexes: The Multi-Branched Chlorophyll Biosynthetic Pathway (MBP)-Sublocation Model
		D Which Chl–Thylakoid Apoprotein Assembly Model Is Validated by Experimental Evidence
			1 Can Resonance Excitation Energy Transfer Between Anabolic Tetrapyrroles and ­Chlorophyll–Protein Complexes be ­Demonstrated?
				(a) Induction of Tetrapyrrole Accumulation
				(b) Selection of Appropriate Chlorophyll .a. Acceptors
				(c) Acquisition of In Situ Emission and Excitation Spectra at 77 K
				(d) Generation of Reference In Situ tetrapyrrole Excitation Spectra
				(e) Processing of Acquired Excitation Spectra
				(f) Demonstration of Resonance Excitation Energy Transfer Between Anabolic Tetrapyrroles and Chlorophyll–Protein Complexes
			2 Development of Analytical Tools for Measuring Distances Separating Various Chlorophyll–Protein Complexes from Anabolic Tetr
				(a) Determination of the Molar Extinction Coefficients of Total Chl .a. In Situ at 77 K
				(b) Estimation of the Molar Extinction Coefficients of Chl a ~F685, ~F695 and ~F735 at 77 K
				(c). Calculation of Distances R Separating Anabolic Tetrapyrroles from Various Chl a–protein Complexes
				(d) Calculation of R.0
				(e) Calculation of k.., the Orientation Dipole
				(f) Calculation of the Overlap Integral .Ju at 77K
				(g) Calculation of n0., the Mean Wavenumber of Absorption and Fluorescence Peaks of the Donor at 77 .K
				(h) Calculation of t0., the Inherent Fluorescence Lifetime of Donors at 77 K
				(i) Calculation of Fy.Da. the Relative Fluorescence Yield of Tetrapyrrole Donors in the Presence of Chl Acceptors In Situ at 77
				(j) Calculation of tD., the Actual Mean Fluorescence Lifetime of the Excited Donor in the Presence of Acceptor at 77 K
				(k) Calculation of R.0. for Proto, Mp(e) and Pchlide .a. donors-Chl .a. Acceptors Pairs at 77 K
				(l) Calculation of E, the Efficiency of Energy Transfer In Situ at 77 K
				(m) Calculation of the Distances That Separate Proto, Mp(e), DV Pchlide .a., and MV Pchlide .a. from Various Chl .a. Acceptors
			3 Testing the Functionalities of the Various Chl–Thylakoid Biogenesis Models
				(a) The Single-Branched Pathway-Single Location Model Is Not Compatible with Resonance Excitation Energy Transfer Between An
				(b) The SBP-Multilocation Model Is Not Compatible with the Realities of Chl Biosynthesis in Green Plants
				(c) The MBP-Sublocation Model Is Compatible with the Realities of Chl Biosynthesis in Green Plants, and with Resonance Excitati
		E Guidelines and Suggestions to Bioengineer Plants with Smaller Photosynthetic Unit Size
			1 Selection of Mutants
				(a) Mutants of Higher Plants Other Than Arabidopsis
				(b) Arabidopsis Mutants
				(c) Lower Plant Mutants
			2 Preparation of Photosynthetic Particles
			3 Determination of Biosynthetic Routes Functional in a Specific Mutant or Photosynthetic Particle
	References
Chapter 2: Evidence for Various 4-Vinyl Reductase Activities in Higher Plants
	I Introduction
	II Materials and Methods
		A Plant Material
		B Light Pretreatment
		C Chemicals
		D Preparation of Divinyl Protochlorophyllide .a
		E Preparation of Divinyl Chlorophyllide .a
		F Preparation of Divinyl Mg-Protoporphyrin Mono Methyl Ester
		G Isolation of Crude and Purified Plastids
		H Preparation of Plastid Membranes and Stroma
		I Preparation of Envelope Membranes
		J Solubilization of [4-Vinyl] Reductase(s) by 3-[(3-Cholamidopropyl)dimethylammonio]-1-Propanesulfonate
		K Assay of [4-Vinyl] Reductase Activities
		L Protein Determination
		M Extraction and Determination of the Amounts of Divinyl and Monovinyl Tetrapyrroles
	III Results
		A Experimental Strategy
		B Detection of [4-Vinyl]Protochlorophyllide .a. Reductase, [4-Vinyl]Mg-Protoporphyrin Monoester Reductase and [4-Vinyl]Mg-Prot
		C Solubilization of [4-Vinyl]Protochlorophyllide .a. Reductase, [4-Vinyl]Mg-Protoporphyrin Monoester Reductase and [4-Vinyl]Mg-
		D 4-Vinyl Side Chain Reduction Occurs Before Isocycle Ring Formation in Photoperiodically-Grown Barley
		E [4-Vinyl] Chlorophyllide .a. Reductase and [4-Vinyl]Protochlorophyllide .a. Reductase Activities do not Occur in Barley Et
		F [4-Vinyl] Protochlorophyllide .a. Reductase Activity Is Detectable in Greening Barley
		G NADPH, but Not NADH is a Cofactor for [4-Vinyl]Chlorophyllide Reductase and [4-Vinyl]Protochlorophyllide Reductase Solubilize
		H The Presence of NADP or Vitamin B.3. in the Incubation Buffer Has No Effect on the Activities of [4-Vinyl]Chlorophyllide .a.
		I Demonstration of [4-Vinyl] Protochlorophyllide a Reductase and [4-Vinyl] Chlorophyllide .a. Reductase Activities in Barley Ch
		J Effects of Various Light Treatments on [4-Vinyl] Clorophyllide .a. Reductase Activity
	IV Discussion
	References
Chapter 3: Control of the Metabolic Flow in Tetrapyrrole Biosynthesis: Regulation of Expression and Activity of Enzymes in th
	I Introduction
	II Mg Protoporphyrin IX Chelatase
		A Structure and Catalytic Activity
		B Control of Expression, Activity and Localisation
		C Analysis of Mutants and Transgenic Plants
	III S-Adenosyl-L-Methionine:Mg Protoporphyrin IX Methyltransferase
	IV Mg Protoporphyrin IX Monomethylester Cyclase
	V Divinyl Reductase
	VI Regulatory Aspects of Mg Porphyrin Synthesis
	References
Chapter 4: Regulation and Functions of the Chlorophyll Cycle
	I Introduction
		A Distribution of Chlorophyll .b
		B Establishment of the Chl Cycle
			1 Chl .b. Synthesis
			2 Chl .b. to Chl .a. Conversion
			3 Why Is the Interconversion of Chl .a. and Chl .b. Called the Chl Cycle?
	II Pathway and Enzymes of the Chlorophyll (Chl) Cycle
A Pathway of the Chl Cycle
		B Enzymes of the Chl Cycle
			1 Chlorophyllide .a. Oxygenase
			2 Chl .b. Reductase
			3 HM-Chl .a. Reductase
	III Diversity and Evolutionary Aspects of Chlorophyllide .a. Oxygenase
		A Diversity of CAO Sequences
		B Domain Structure of CAO
		C Distribution of Chl .b. Reductase
	IV Regulation of the Chl Cycle
		A Regulation of the Chl .a. to .b. Conversion
			1 Transcriptional Control
			2 The Signal Transduction Pathway
			3 Post-transcriptional Control
		B Regulation of the Chl .b. to .a. Conversion
	V Roles of the Chl Cycle in the Construction of the Photosynthetic Apparatus
		A Coordination of the Chl cycle and the Construction of the Photosynthetic Apparatus
		B Construction and Deconstruction of the Photosynthetic Apparatus and Its Coordination with the Chl .b. to .a. Conversion Syste
	References
Chapter 5: Magnesium Chelatase
	I Introduction
	II The 40 kDa Subunit
	III Comparision of 40 kDa Subunit with the Golgi Membrane Protein NSF-D2, Heat Shock Locus Protein HslU and the .d¢. Subun
	IV The 70 kDa Subunit and Its Complex Formation with the 40 kDa Subunit
	V The 140 kDa Subunit
	VI The Gun4 Protein
	References
Chapter 6: The Enigmatic Chlorophyll .a. Molecule in the Cytochrome .b6..f. Complex
	I Introduction: On the Presence of Two Pigment Molecules in the Cytochrome .b6..f. Complex
	II Crystal Structures of the Cyt .b6..f. Complex: The Environment of the Bound Chlorophyll
	III Additional Function(s) of the Bound Chlorophyll
	IV Additional Function of the .b.-Carotene
	References
Chapter 7: The Non-mevalonate DOXP/MEP (Deoxyxylulose 5-Phosphate/Methylerythritol 4-Phosphate) Pathway of Chloroplast Isopre
	I Introduction
	II The Cytosolic Acetate/Mevalonate (MVA) Pathway of Isopentenyl Pyro phosphate (IPP) Biosynthesis and Its Inhibition
	III The Plastidic DOXP/MEP Pathway of IPP and Its Inhibition
	IV Labeling Experiments of Chloroplast Prenyllipids
	V Compartmentation of Isoprenoid Biosynthesis in Plants
	VI Branching Point of DOXP/MEP Pathway with Other Chloroplast Pathways
	VII Cross-Talk Between Both Cellular Isoprenoid Pathways
	VIII Earlier Observations on Cooperation of Both Isoprenoid Pathways
	IX Distribution of the DOXP/MEP and the MVA Pathways in Photosynthetic Algae and Higher Plants
	X Evolutionary Aspects of the DOXP/MEP Pathway
	XI Biosynthesis of Isoprene and Methylbutenol
	XII Level of Chlorophylls, Carotenoids and Prenylquinones in Sun and Shade Leaves
	XIII Inhibition of Chlorophyll and Carotenoid Biosynthesis by 5-Ketoclomazone
	XIV Conclusion
	References
Chapter 8: The Methylerythritol 4-Phosphate Pathway: Regulatory Role in Plastid Isoprenoid Biosynthesis
	I Introduction
	II Regulatory Role of the MEP Pathway in Plastid Isoprenoid Biosynthesis
	III Crosstalk Between the MVA and the MEP Pathways
	IV Perspectives for Metabolic Engineering of Plastid Isoprenoids
	References
Chapter 9: The Role of Plastids in Protein Geranylgeranylation in Tobacco BY-2 Cells
	I Introduction
	II Protein Isoprenylation in Plants
		A The Chemical Modification of a C-Terminal Cysteine
		B Functions of Protein Prenylation in Plants
		C Isoprenylation of Proteins in Tobacco BY-2 Cells
		D Origin of the Prenyl Residue Used for Protein Modification
			1 A Double Origin of Prenyl Diphosphates
			2 Construction of a Tool to Test the Origin of Geranylgeranyl Residues in Prenylated Proteins
				(a) State of the Art
				(b) Tobacco BY-2 Cell Suspensions as a Suitable Tool
				(c) Description of the  System and Results
	III Conclusion and Perspectives
	References
Chapter 10: The Role of the Methyl-Erythritol-Phosphate (MEP)Pathway in Rhythmic Emission of Volatiles
	I Introduction
	II The MEP Pathway and Rhythmic Emission of Floral Volatiles
	III The MEP Pathway and Rhythmic Emission of Leaf Volatiles
	IV The MEP Pathway and Rhythmic Emission of Herbivore-Induced Plant Volatiles
	V The MEP Pathway and Rhythmic Emission of Isoprene
	VI Conclusions
	References
Chapter 11: Tocochromanols: Biological Function and Recent Advances to Engineer Plastidial Biochemistry for Enhanced Oil Seed
	I  Introduction
	II  Tocochromanol Biosynthesis and Regulation
	III Tocochromanol Pathway Engineering for Enhancement of Vitamin E
	IV Optimized Tocochromanol Composition
	V Enhancement of Total Tocochromanol Content
	VI Enhancement of Tocotrienol Biosynthesis
	VII Conclusions and Outlook
	References
Chapter 12: The Anionic Chloroplast Membrane Lipids: Phosphatidylglycerol and Sulfoquinovosyldiacylglycerol
	I Introduction
	II Biosynthesis of Plastidic Phosphatidylglycerol
	III Biosynthesis of Sulfoquinovosyldiacylglycerol
	IV Functions of Plastid Phosphatidylglycerol
	V Functions of Sulfoquinovosyldiacylglycerol
	VI The Importance of Anionic Lipids in Chloroplasts
	VII Future Perspectives
	References
Chapter 13: Biosynthesis and Function of Monogalactosyldiacylglycerol (MGDG), the Signature Lipid of Chloroplasts
	I Introduction
	II Identification of MGDG Synthase in Seed Plants
	III Biochemical Properties of MGDG Synthase
		A Enzymatic Features of MGDG Synthase
		B Subcellular Localization of MGDG Synthase
		C Three-Dimensional Structure of MGDG Synthase
		D Two Types of MGDG Synthase in Arabidopsis
		E MGDG Synthesis in Non-photosynthetic Organs
	IV Function and Regulation of MGDG Synthase
		A Regulation of Type A MGDG Synthase
		B Regulation of Type B MGDG Synthase
		C In Vivo Function of MGDG Synthase by Mutant Analyses
	V Substrate Supply Systems for MGDG Synthesis
		A DAG Supply to the Outer Envelope
		B DAG Supply to the Inner Envelope
	VI MGDG Synthesis in Photoautotrophic Prokaryotes
	VII Future Perspectives
	References
Chapter 14: Synthesis and Function of the Galactolipid Digalactosyldiacylglycerol
	I Introduction
	II Structure and Occurrence of Digalactosyldiacylglycerol
	III Synthesis of Digalactosyldiacylglycerol and Oligogalactolipids
	IV Function of Digalactosyldiacylglycerol in Photosynthesis
	V Digalactosyldiacylglycerol as Surrogate for Phospholipids
	VI Changes in Galactolipid Content During Stress and Senescence
	VII Conclusions
	References
Chapter 15: The Chemistry and Biology of Light-Harvesting Complex II and Thylakoid Biogenesis: .raison d’etre. of Chlorophyll
	I Introduction
		A Chlorophyll .a
		B Chlorophyll .b
		C Chlorophyll .c
		D Chlorophyll .d
	II Coordination Chemistry of Chlorophyll and Ligands
	III Binding of Chlorophyll to Proteins
	IV Chlorophyll Assignments in Light Harvesting Complex II (LHCII)
	V Cellular Location of Chlorophyll .b. Synthesis and LHCII Assembly
	VI Chlorophyllide .a. Oxygenase
	VII Conclusions
	References
Chapter 16: Folding and Pigment Binding of Light-Harvesting Chlorophyll .a/b. Protein (LHCIIb)
	I Introduction
	II Time-Resolved Measurements of LHCIIb Assembly In Vitro
		A Fluorescence as a Monitor for LHCIIb Assembly
		B A Two-step Model of Pigment Binding
		C Protein Folding During LHCIIb Assembly
	III Concluding Remarks
	References
Chapter 17: The Plastid Genome as a Platform for the Expression of Microbial Resistance Genes
	I Introduction
	II Yield and Resistance
	III .Aspergillus flavus.: Managing a Food and Feed Safety Threat
		A Economic and Health Impacts
		B Approaches to Intervention
	IV The Case for Transgenic Interventions
		A Modifying the Nuclear Genome for Resistance
	V Plastid Transformation
		B Features of the Plastid Expression System
			1 The Plastome
				(a) Integration of Foreign Sequences
				(b) Maternal Inheritance
		C Moving Beyond the Model System
	VI Identifying Candidate Genes for Aflatoxin Resistance
		A Chloroperoxidase
			1 Antimicrobial Potential
			2 Expression of CPO-P in Transgenic Plants
	VII An Environmentally Benign Approach
		A Plastid Transformation Vector
		B Determinants of Foreign Gene Expression in Plastids
			1 The .psbA. 5.¢. UTR
				(a) The Potential of .psbA. 5.¢. UTR Stems From Its Endogenous Role in Plastids
				(b) Translational Control Is Highly Regulated and Dependent on Imported Trans-acting Protein Factors
				(c) Light Regulation of Translation Via the .psbA. 5.¢. UTR
		C The CPO-P Transplastomic Lines
			1 Evaluating CPO-P Expression
				(a) Protein Expression
				(b) Analysis of Foreign Transcripts
				(c) Continued Analysis
	VIII Future Challenges: Control of Aflatoxin Contamination in Cottonseed
		A Taking a Direct Approach
		B Taking an Indirect Approach
			1 Drought Tolerance
			2 Resistance to Herbivory
		C Generation of Transplastomic Cotton
	IX Conclusion
	References
Chapter 18: Chloroplast Genetic Engineering: A Novel Technology for Agricultural Biotechnology and Bio-pharmaceutical Industr
	I Introduction
	II Genome and Organization
	III Concept of Chloroplast Transformation
	IV Advantages of Plastid Transformation
	V Chloroplast Transformation Vectors and Mode of Transgene Integration into Chloroplast Genome
	VI Methods of Plastid Transformation and Recovery of Transplastomic Plants
	VII Current Status of Plastid Transformation
	VIII Application of Chloroplast Technology for Agronomic Traits
	IX Chloroplast-Derived Vaccine Antigens
	X Chloroplast-Derived Biopharmaceutical Proteins
	XI Chloroplast-Derived Industrially Valuable Biomaterials
	References
Chapter 19: Engineering the Sunflower Rubisco Subunits into Tobacco Chloroplasts: New Considerations
	I Introduction
	II Transforming the Tobacco Plastome with Sunflower Rubisco Genes
		A Replacing the Tobacco .rbc.L with Sunflower .rbc.L.S
		B Co-transplanting .rbc.L.S. and a Codon-Modified Sunflower .cmrbc.S Gene
			1 A Need to Co-engineer Cognate L- and S-Subunits
		2 Altering the Codon Bias of a Sunflower .Rbc.S.s. Gene
			3 Using the T7g10 5.¢.UTR to Regulate Sunflower S-Subunit Translation
		C Transformation, Selection and Growth of the Transplastomic Lines
	III Inadvertent Gene Excision by Recombination of Duplicated .psb.A 3.¢.UTR Sequence
		A Preferential Loss of Plastome Copies Containing .cmrbc.S.S
		B Why Were the .cmrbc.S.S. Containing Plastome Copies Lost?
	IV Simple Removal of .aad.A in T.0. t.Rst.SLA by Transient CRE Recombinase Expression
		A Bacteriophage P1 CRE-.lox. Site-specific Recombination
		B Removing .aad.A by Bombarding with Plasmid pKO27
		1 Selection and Screening for .Daad.A Lines
			2 Screening the T.1. Progeny for .aad.A Loss and No Incorporation of the pKO27 T-DNA
	V Growth Phenotypes of the tob.Rst., t.Rst.LA and t.Rst.L Lines
		A Elevated CO.2. Partial Pressures Augment the Growth of the Juvenile Transformants
		B The Comparable Phenotype and Growth Rates of the Transgenic Lines
			1 Differences in Leaf and Apical Meristem Development
			2 Shoot Development
		C Leaf and Floral Development
	VI Expression of the Hybrid L.s.S.t. Rubisco in Mature Leaves
		A Steady-State .rbc.L.S. mRNA Levels
		B Rubisco and Protein Content
		C Translational Efficiency and/or Folding and Assembly Limit L.s.S.t. Production
	VII Whole Leaf Gas Exchange Measurements of the L.s.S.t. Kinetics
		A Measuring Gamma Star (.G.*)
		B Measuring the L.s.S.t. Michaelis Constants for CO.2. and O.2
	VIII Future Considerations for Transplanting Foreign Rubiscos into Tobacco Plastids
		A Improving L.s.S.t. Synthesis
			1 Limitations to Translational Processing of .rbc.L.S
			2 Subunit Assembly Limitations
		B The Assembly and Kinetic Capacity of Other Hybrid Rubiscos
		C Constraints on S-Subunit Engineering in Tobacco
		D Rubisco Activase Compatibility
	IX Quicker Screening of the Assembly and Kinetics of Genetically Modified L.8.S.8. Enzymes in Tobacco Chloroplasts
	References
Chapter 20: Engineering Photosynthetic Enzymes Involved in CO.2.–Assimilation by Gene Shuffling
	I Introduction
	II Potential Targets for Improving Plant Photosynthesis
	III Directed Molecular Evolution Provides a Useful Tool to Engineer Selected Enzymes
	IV Improving Rubisco CatalyticEfficiency by Gene Shuffling
		A Attempts to Express .Arabidopsis thaliana. Rubisco in .Chlamydomonas reinhardtii
		B Shuffling the .Chlamydomonas reinhardtii. Rubisco Large Subunit
	V Improving Rubisco Activase Thermostability by Gene Shuffling
	VI Future Prospects
	References
Elevated CO.2. and Ozone: Their Effects on Photosynthesis
	I Introduction
	II Regulation of the Photosynthetic Apparatus: Metabolic and Environmental Signals
	III Possible Scenarios Explaining Effects of Elevated [CO.2.] and [O.3.] on Plant Behavior in the Altered Earth Atmosphere
		A Plant Responses to Elevated [CO.2]
		B Plant Responses to Tropospheric [O.3.]
		C Combined Effects of [CO.2] and [O.3..]
	IV Benefits from Model Species:.Arabidopsis thaliana. and .Thellungiella halophila
	V Discussion
		A The Importance of Model Species
		B Gene Networks Explaining Transcript Behavior
	VI Conclusions
Chapter 22: Regulation of Photosynthetic Electron Transport
	I Introduction
	II Chlorophyll Fluorescence: A Non-disruptive Tool for Electron Transport Analysis
	III Thermal Dissipation of Absorbed Excessive Light Energy from PSII
	IV Balancing Excitation Energy Between Photosystems by State Transition
	V Photorespiration and the Water–Water Cycle: Alternative Electron Sinks?
	VI The Discovery of PGR5-Dependent PSI Cyclic Electron Transport
	VII PSI Cyclic Electron Transport Mediated by Chloroplast NAD(P)H Dehydrogenase
	VIII PSI Cyclic Electron Transport and Thermal Dissipation
	IX PSI Cyclic Electron Transport and State Transition
	X The Water–Water Cycle and PSI Cyclic Electron Transport
	XI Concluding Remarks
	References
Chapter 23: Mechanisms of Drought and High Light Stress Tolerance Studied in a Xerophyte, .Citrullus lanatus. (Wild Watermelon)
	I Introduction
	II Experimental Procedures
	III Physiological Response of Wild Watermelon
	IV Enzymes for Scavenging Reactive Oxygen Species
	V Cytochrome .b561. and Ascorbate Oxidase
	VI Global Changes in the Proteomes
	VII Citrulline Metabolism and Function
	VIII Concluding Remarks
	References
Chapter 24: Antioxidants and Photo-oxidative Stress Responses in Plants and Algae
	I Types of Reactive Oxygen Species
	II Sources of Reactive Oxygen Species in Algae and Plants
	III Functions of Reactive Oxygen Species
	IV Oxidative Damage in Chloroplasts
	V Avoidance of Reactive Oxygen Species Production
	VI Non-enzymatic Mechanisms for Scavenging Reactive Oxygen Species
		A Hydrophilic Antioxidants
			1 Ascorbate
			2 Glutathione
		B Lipophilic Antioxidants
			1 Tocopherol
			2 Carotenoids
		C Antioxidant Interactions
	VII Enzymatic Mechanisms for Scavenging Reactive Oxygen Species
		A Superoxide Dismutase
		B Catalase
		C Ascorbate Peroxidase
		D Glutathione Peroxidase
		E Thioredoxin
		F Glutaredoxin
		G Peroxiredoxin
	References
Chapter 25: Singlet Oxygen-Induced Oxidative Stress in Plants
	I Introduction
		II Formation of Singlet Oxygen in Plants
	III Generation of Singlet Oxygen from Chlorophyll Biosynthesis Intermediates
	IV Porphyrin-Generating Compounds
		A 5-Aminolevulinic Acid
		B Diphenyl Ethers
	V Type I and Type II Photosensitization Reactions of Tetrapyrroles
	VI Intracellular Destruction of Singlet Oxygen
	VII Singlet Oxygen-Mediated Oxidative Damage to the Photosynthetic Apparatus
		A Generation of Tetrapyrrole-Induced Singlet Oxygen in Chloroplasts
		B Singlet Oxygen-Induced Impairment of the Electron Transport Chain
		C Role of Singlet Oxygen Scavengers
		D Impact of .1.O.2. on Chlorophyll a Fluorescence
		E Effect of Singlet Oxygen on Thermoluminiscence
	VIII Singlet Oxygen-induced Oxidative Damage in Mutants
		A Chlorophyll Anabolic Mutants
		B Chlorophyll Catabolic Mutants
	IX Future Prospects
	References
Subject Index
                        
Document Text Contents
Page 2

The Chloroplast

Page 226

Yuki Nakamura et al.

for Type A function and what it would be like if
MGD1 was completely eliminated. Moreover, it
was still uncertain whether MGDG is essential for
chloroplast function. To address this question, we
recently isolated and characterized a null mutant
of MGD1, designated mgd1-2, obtained from an
available T-DNA tagged mutant line (Kobayashi
et al., 2007). When the siliques of mgd1/MGD1
heterologous mutant were examined, about 25%
of the embryos were aberrant, suggesting that these
seeds may be mgd1-2/mgd1-2 homozygous with a
likely embryonic lethal phenotype. Interestingly,
however, when the wrinkled seed were planted,
they germinated. The phenotype of mgd1-2 was
intriguing; the mutant plant was very small and
white compared to WT. Lipid analyses of mgd1-2
revealed that plastidic membrane lipids, such as
MGDG, DGDG, and sulfoquinovosyldiacylglyc-
erol (SQDG), were hardly detectable, presumably
due to the deficiency in chloroplasts formation.
Indeed, an observation of mutant chloroplasts by
electron microscopy showed a disrupted structure
of thylakoid membranes. Thus, results of analy-
ses with mgd1 (referred to as mgd1-1 hereafter)
and mgd1-2 indicated that MGD1 is responsible
for the bulk of MGDG synthesis and cannot be
replaced by Type B MGDG synthases. Therefore,

its function is indispensable for photosynthetic
ability and formation of proper chloroplasts.

As for type B MGD (MGD2 and MGD3),
preliminary results of mutant analyses showed
no significant impact on lipid metabolism in
photosynthetic organs, although analyses in non-
photosynthetic organs are still ongoing. Since
Awai and co-workers showed that MGD2 and
MGD3 were expressed in different organs (Awai
et al., 2001; Kobayashi et al., 2004), it is of great
interest to find out whether these two isozymes
are functionally redundant or have distinct
functions each other (Fig. 1).

V Substrate Supply Systems
for MGDG Synthesis

The substrates for MGDG synthesis are DAG
and UDP-Gal. Here, our focus is on the supply of
DAG for MGDG biosynthesis. DAG is supplied
by multiple metabolic pathways, and production
of DAG itself presents a complex problem as this
lipid class serves as substrate for galactolipids,
phospholipids and even triacylglycerol (TAG).
For the enzymes involved in the biosynthesis of
DAG and its precursors, readers are referred to

Fig. 1. Physiological functions of type A and type B MGDs for plant growth. Type A MGD1 are expressed widely in photosyn-
thetic tissues. By contrast, Type B MGD2 and 3 showed intense expression particularly in non-photosynthetic tissues during Pi
starvation and pollen tube growth.

Photosynthetic tissues Non-photosynthetic tissues

Embryogenesis

Photosynthetic
membrane
construction

Pollen tube growth

Pi-stress response in the root

Type A
(atMGD1)

Type B
(atMGD2,3)

192

Page 227

13 Biosynthesis and Function of MGDG

Joyard et al. (1998). The biosynthesis of MGDG
occurs exclusively in plastids (Douce and Joyard,
1980). However, DAG is known to be supplied
either within plastids (prokaryotic pathway) or by
way of the ER (eukaryotic pathway) (Roughan
and Slack, 1982). Early studies suggested that
in both pathways, DAG is derived from differ-
ent lipid precursors. In the prokaryotic pathway,
DAG is produced from phosphatidic acid (PA) by
PA phosphatase (PAP) (Joyard and Douce, 1977).
On the other hand, eukaryotic DAG is generally
assumed to be derived from PC synthesized in the
ER (PC hypothesis). This hypothesis is based on
in situ pulse chase studies, where radiolabel tran-
siently allocated to the cellular pool of PC being
incorporated mainly into MGDG (Roughan, 1970;
Heinz, 1977; Douce and Joyard, 1980; Roughan
and Slack, 1982). This hypothesis involves (1) the
synthesis of PC, (2) its transfer (or that of DAG)
to chloroplasts, and (3) the integration of the DAG
backbone into MGDG and DGDG. Although
the transport manner and the transported lipid
have not been identified yet, lysoPC (A. porrum;
Mongrand et al., 1997, 2000), DAG (B. napus;
Williams et al., 2000) and PA (A. thaliana; Xu
et al., 2005; Awai et al., 2006b) have been pro-
posed recently as the possible transported lipid.
An early study showed the possibility that PC
could be the transported lipid: when spinach chlo-
roplasts were pre-incubated with [14C]-containing
liposomes and phospholipid transfer proteins prior
to incubation with phospholipase C (PLC) and
UDP-Gal, formation of [14C]MGDG was observed
(Oursel et al., 1987). Recently, Jouhet and co-
workers reported with suspension culture of A.
pseudoplatanus that, during phosphate starved
conditions which activate galactolipid biosynthe-
sis, a transient increase of PC was followed by its
rapid decrease and concomitant increase in DAG
(Jouhet et al., 2003). Furthermore, the fatty acid
composition of PC and DAG were very similar,
suggesting that DAG is supplied by the hydroly-
sis of PC. Another report by Andersson and co-
workers who studied the conditions that would
allow the conversion of chloroplast-localized PC
into the precursor for MGDG synthesis showed
that cytosolic phospholipase D (PLD) activity that
resides in the >100kDa fraction is involved in the
substrate supply for MGDG synthesis (Anders-
son et al., 2004). Since PLD reaction gives rise
to PA, subsequent reaction by PAP should be

coupled to the reaction. This idea of the combina-
tory two-step reaction seems somewhat irrational,
but the involvement of activity for direct hydrol-
ysis by a PC-hydrolyzing PLC (PC-PLC) is not
clear even though the activity itself was reported
in several studies (Kates, 1955; Strauss et al.,
1976; Chrastil and Parrish, 1987; Rouet-Mayer
et al., 1995; Scherer et al., 2002). However, sig-
nificant progress has been made in recent 3 years
with Arabidopsis for identifying and characteriz-
ing key enzymes involved in this mechanism. As
mentioned earlier, Arabidopsis has the machinery
for MGDG synthesis both at the outer and inner
envelope membrane of chloroplast. Because these
two pathways are separated from each other (Ben-
ning and Ohta, 2005), the DAG supply for these
two pathways could rely on independent enzymes/
mechanisms (Fig. 2).

A DAG Supply to the Outer Envelope

Outer envelope-localized MGDG synthesis does
not contribute to the bulk of MGDG synthesis
under normal growth condition (Benning and Ohta,
2005). Therefore, the outer envelope-specific flux
is often masked by the inner envelope-localized
pathway, and therefore it is difficult to estimate
the contribution of the outer envelope system
(Benning and Ohta, 2005). It was reported that
phosphate starvation activates specifically the
outer envelope-localized pathway. Our group made
use of this condition to identify which metabolic
pathway is activated for DAG supply (Nakamura
et al., 2005). Hydrolysis of PC to yield DAG is
shown to be highly induced upon Pi starvation, and
moreover, inhibition of PLD activity by n-BuOH
showed no significant decrease in the activity,
suggesting that the DAG supply from PC is medi-
ated by one-step hydrolysis of PC-PLC. Based on
homology search using known bacterial PC-PLCs,
six putative PC-PLCs were detected in Arabidop-
sis and designated non-specific phospholipase C
(NPC). Expression studies revealed that one of
them, NPC4, was strongly induced upon Pi star-
vation. In vitro enzyme assays of recombinant
NPC4 showed significant PLC activity for PC and
phosphatidylethanolamine (PE) but not phosphati-
dylinositol (PI) or PA. Its subcellular localization
using a specific anti- NPC4 antibody was con-
firmed to be in the plasma membrane. Two inde-
pendent T-DNA lines giving rise to npc4 knock

193

Page 452

Subject Index

Synechocystis, 21, 41, 42, 44–46, 62, 63, 66, 109,
86, 159–163, 165, 177, 196, 197, 204,
386, 388, 390, 391

Synechocystis PCC6803, 42, 46, 62, 63, 159,
177, 196

T
tAPX gene network, 337, 339
Taxol, 96, 121, 122, 128
Terpenes

biosynthesis, 102, 105, 140, 141, 143
diterpenes, 96, 101, 105, 113, 114, 128,

140, 149
monoterpenes, 96, 101, 105, 110, 113,

114, 120, 122, 128, 140–144,
148, 149

sesquiterpenes, 96, 101, 102, 105, 106, 113,
120, 128, 140–143, 148

Tetrapyrroles, 7, 10–21, 27, 30, 32, 39–49, 63, 208,
217, 218, 400–404

Therapeutic proteins, 263, 264, 272, 273,
277, 278

Thermal dissipation, 348–350, 352, 353,
355–356

Thermoluminescence, 406
Thermosynechococcus elongatus, 86, 176, 206,

383
Thin layers of silica gel H, 29
Thioredoxin, 42, 187, 326, 382, 390–391
Thylakoid

apoproteins, 8–9, 11–12
biogenesis, 213–226
membrane, 7, 9, 11, 12, 32, 40, 63, 69–73,

148, 159, 172, 174, 175, 177–180,
189, 191, 192, 205, 208, 214, 222,
224, 232, 238, 239, 241, 254, 326,
352, 353, 356, 357, 367, 368, 373,
382, 383, 386, 400–406

Tobacco, 42, 44, 45, 59, 67, 72, 102, 113, 121,
122, 127–134, 161, 163, 177, 197, 246,
250–253, 255, 257, 263, 265–267, 269,
271–279, 285–303, 309, 310, 316, 320,
352, 354, 382, 386, 388, 389, 407, 408

BY-2 cells, 127–134
plastome, 251, 287–290, 302, 303

Tocochromanols, 155–166
Tocopherol, 121, 122, 155–166, 383–388, 402

level of, 112, 158
localisation, 96

Tocotrienol, 155–166

Transformation, 64, 251–254, 256, 257, 264,
267–275, 278–280, 287, 290, 292, 300,
302, 303, 309, 313, 314, 316, 320, 354,
374, 407

Transgene, 123, 252, 253, 257, 263, 264, 267–275,
279, 289, 291, 293, 314

cassette, 267, 269, 270
containment, 253, 257, 263, 267, 275

Transition dipoles, 12
Translation efficiency, 254, 298
Transmembrane electron transport, 370
Transplastomic, 251–257, 270–272, 274, 279,

280, 288, 290-296, 298
Trigalactosyldiacylglycerol (TGDG), 196, 205
Tropospheric ozone, 324, 325, 327, 331
Tyrosine, 62, 157, 160, 163, 289, 334

U
Ubiquinone, 96, 101, 102, 120, 128

biosynthesis, 101, 102, 120
localisation, 96

UDP-sulfoquinovose (UDP-SQ), 175, 176, 179
Unfolded state, 8–10, 20
Uridine-diphosphate-galactose (UDP-Gal),

186–188, 192, 193, 205, 208
Uroporphyrin III, 408

V
Vaccine antigens, 263–265, 269, 272, 273,

275–277
4VChlR. See 4-Vinyl Chl a reductase
4VCR. See 4-Vinyl chlorophyllide a reductase
4-Vinyl Chl a reductase (4VChlR), 8, 28, 35
4-Vinyl chlorophyllide a reductase (4VCR), 8,

28–36
Vinyl groups, 27, 58
[4Vinyl] Mg-protoporphyrin monoester reductase

(4VMpeR), 29–31, 34–37
[4-Vinyl] Mg-proto reductase (4VMPR), 8,

28–31, 35
4-Vinyl Pchlide a reductase (4VPideR),

8, 27–36
[4-vinyl] reductase (4VR), 8, 26–35
Violaxanthin, 232, 350, 384, 387, 402
Violaxanthin de-epoxidase, 350, 384, 387
Vitamin B3, 33
Vitamin B6, 402, 407
Vitamin E, 112, 114, 155–166
Vitamin K, 4, 112, 165

422

Page 453

Subject Index

(4VMpeR). See [4Vinyl] Mg-protoporphyrin
monoester reductase

4VMPR. See [4-Vinyl] Mg-proto reductase
4VPideR. See 4-Vinyl Pchlide a reductase
4V-Proto, 34
4VR isoforms, 28

W
Walker B motif, 41, 80, 81
Water soluble chlorophyll

binding proteins, 402
Water water cycle, 348, 349, 351–352,

356, 391, 392

Wave number, 16–17
Wild watermelon, 363–374

X
Xantha−F, 43, 79, 80, 85
Xantha−H gene, 80
Xanthophyll cycle, 60, 112, 207, 350, 387
Xanthophylls, 220, 222, 386, 387, 402
Xerophytes, 363–374

Z
Zeaxanthin, 112, 207, 350, 384, 387, 399, 402

423

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