Prologue

As the industrial revolution that has been based on utilization of fossil fuels nears its end [(Ker RA (2007) Even oil optimists expect energy demand to outstrip supply.], the next industrial revolution will most likely need development of alternate sources of clean energy. In addition to the development of hydroelectric power, these efforts will probably include the conversion of wind, sea wave motion and solar energy [Solar Day in the Sun (2007) Business week, October 15, pp 69-76] into electrical energy. The most promising of those will probably be based on the full usage of solar energy. The latter is likely to be plentiful for the next two to three billion years. Most probably, that usage will take advantage of (a) the physical conversion of solar to electric energy [Pooley E (2007) The Last temptation of Al Gore. Time, May 28], (b) solar energy energy converting systems. [Biology and Technology for Photochemical Fuel Production (2009). Hambourger, M, Gary F. Moore GF, Kramer, DM, Gust, D, Moore, AL Moore, TA. Chem. Soc. Rev., 25 – 35], and (c) the biological engineering of higher photosynthetic efficiencies for the generation of fixed carbon.

The world population of about 6 billion is expected to increase to 9 billion by the year 2030. It may increase even further by the end of this century. Worldwide, there has been a progressive decline in cereal yield and at present the annual rate of yield increase is below the rate of population increase [Somerville C, Briscoe J (2001) Genetic Engineering and Water. Science 292: 2217]. Since it will be difficult to increase the land area under cultivation without serious environmental consequences, the increased demand for food and fiber will have to be met by higher agricultural plant productivity.

With the imminent depletion of finite oil reserves [Eugene L (2007) From peak oil to dark ages? Business Week, June 25], there has been considerable interest in the conversion of biomass into biofuels. For such a technology to become financially competitive, biomass transportation should not exceed a radius of about 25 miles. In other words, a bioconversion plant should be built in the center of every 2000 sq. miles of farmland. Such a caveat would be greatly alleviated by higher photosynthetic efficiencies and more biomass production per unit area.

According to Times Magazine (April 30, 2007 issue, one fifth of the US corn crop is presently converted into ethanol, which is considered to burn cleaner than gasoline and to produce less greenhouse gases. In order to meet a target of 35 billion gallons of ethanol produced by the year 2017, the entire US corn crop would need to be turned into fuel. But crops such as corn and sugar cane cannot yield enough to produce all the needed fuel. Furthermore, even if all available starch is converted into fuel, it would only produce about 10% of our gasoline needs [Service RF (2007) Biofuels researchers prepare to reap a new harvest. Science 315: 1488-1491]. Also, corn is used for a multitude of food products and diverting too much of the corn crop to ethanol would cause dramatic rises in the cost of food. All these calculations are based on a photosynthetic conversion rate of about 0.2-0.4% of incident radiation. If photosynthetic efficiency were to be increased to approach the 12 % upper theoretical limit of photosynthetic energy conversion to fixed carbon [(Lein S, San Pietro A. (1975) An inquiry into biophotolysis of water to produce hydrogen, RANN, pp 50; Xin-Guang Zhu, Stephen P Long, Donald R Ort (2008) What is the maximum efficiency with which photosynthesis can convert solar energy into biomass? Current Opinion in bioterchnology 19: 153-159], there would be more than enough land to meet all of the world corn needs [Rebeiz CA, Kolossov VL, Kopetz KK (2004). Chloroplast Bioengineering 1. Photosynthetic Efficiency, Modulation of the PhotosyntheticUunit Size, and the Agriculture of the Future. In: Agricultural Applications of Green Chemistry (W. M. Nelson, ed) ACS Symposium Series 887 pp 81-105.].

According to the US Department of Energy [Service RF (2007) Biofuels researchers prepare to reap a new harvest. Science 315: 1488-1491], the US could convert 1.3 billion dry tons a year of biomass to 60 billion gallons of ethanol with little impact on food or timber harvests and in the process meet 30% of the nation’s transportation fuel. But converting cellulose and hemicellulose to fuel is far more difficult than starting with simple sugar as is done in Brazil with sugar cane or in the US as is done with corn starch. This is due to the fact that agricultural and forest wastes are composed of cellulose, a polymer of six-carbon glucose, and of hemicellulose, a branched polymer composed of xylose and other five-carbon sugars and lignin. To convert biomass to ethanol, the complex carbohydrates must be first made available. However there is no naturally occurring organism that can convert xylose and other 5-carbon sugars to ethanol [Service RF (2007) Biofuels researchers prepare to reap a new harvest. Science 315: 1488-1491]. Even if this problem were solved, the conversion of biomass to ethanol would be greatly alleviated by higher photosynthetic conversion efficiencies.

In this respect it is interesting to mention the large scale effort of British Petroleum in conjunction with the University of California at Berkeley and the University of Illinois at Urbana-Champaign in pursuing the development of biofuels. Also, efforts focused on breeding more efficient fiber plants, miscanthus and switchgrass [Kintish E (2008) Sowing the seeds for high energy plants. Science 320: 478-483], Jatropha seeds for an oil-based biofuel [Padget T, Myers F (2009) Time Magazine, February 9, p 50], and Rutabagas (Benning C, Personal communication) are under way. Additional efforts are also dealing with the possibility of converting algal biomass into biofuels [Edmonson G (2007) Here comes pond scum power. Business week, December, pp 65-66].

In December 2006, the National Aeronautic and Space Organization (NASA) announced plans to establish a permanent international base camp on the moon by the year 2024. Sir Richard Branson stated [Thomas CB, Island N (2007) The space cowboys, Time March 5: 52-58] that prices on Virgin Galactic, his space company, will eventually drop so that millions can go into space. If this heralds the beginning of extra-terrestrial space colonization, it is time to start thinking of alternatives to conventional agriculture by developing systems capable of converting solar energy, water as a source of electrons, and carbon dioxide into food fiber and energy at rates far above the photosynthetic rates presently experienced. Due to the eventual dwindling of water resources around the globe [Somerville C, Briscoe J (2001) Genetic Engineering and Water. Science 292: 2217], and the dearth of water in deserts and in space stations, the use of water as a source of electrons instead of an evapotranspirant would be a much needed feature of this putative agriculture.

The conversion of solar energy, water as a source of electrons, and carbon dioxide into carbohydrates at rates that approach the upper photosynthetic theoretical limits was raised in a 1974 essay [Rebeiz CA (1974) Cell-free aAgriculture: Fiction or Realty? Illinois Research 16: 3-4] following the reporting of the biosynthesis of chlorophyll in vitro [Rebeiz CA, Castelfranco P (1971) Protochlorophyll biosynthesis in a cell-free system from higher plants. Plant Physiol. 47: 24-32; Rebeiz CA, Castelfranco P (1971) Chlorophyll biosynthesis in a cell-free system from higher plants. Plant Physiol. (47): 33-37]. In a 1974 exchange of letters with Melvin Calvin, this possibility was debated by Calvin and Rebeiz, and Calvin suggested that the ultimate system that will achieve that goal will be a synthetic one.

Now, 45 years later, we believe that enough biochemical and molecular biological knowledge has accumulated to render this dream amenable to experimentation. As Confucius stated, “A journey of a Thousand miles has to Start with the FirstSstep.” Indeed conventional agriculture is one of the few human activities that have not undergone a revolution to join other activities such as flying, defying gravity by landing on the moon, and crossing underwater the polar cap. Indeed, Craig Venter recently declared that he is about to succeed in creating an artificial microbe [Carey J (2007) On the brink of artificial life. Business Week, June 27 p 40]. Other research teams around the country are following suit.

In this book, an effort is made to take Confucius’s first steps. An attempt will be made to explore that first step in the light of present knowledge of the chemistry, biochemistry, and molecular biology of the greening process. We believe, that in the near future, the bioengineering of improved photosynthetic efficiency would require thorough knowledge of the biosynthesis of photosynthetic membrane components such as heme, chlorophylls, carotenoids, quinones, and lipids, thorough knowledge of photosynthetic membrane apoprotein biosynthesis, deeper understanding of the biosynthesis and regulation of the assembly of pigment-apoprotein complexes, and deeper knowledge of various facets of photon capture and carbon fixation. Another acknowledged way to increase agricultural productivity is to bioengineer chloroplasts more adapted to deal with stress and to alter the kinetic properties of the primary CO2-assimilating enzyme, Rubisco, a multi-subunit protein located in the chloroplasts that is encoded by genes located in both the nucleus and chloroplast. The results of initial attempts at the bioengineering of Rubisco indicate that (a) increased knowledge of the factors controlling and coordinating gene expression in these two organelles, (b) better understanding of the significance of post-translational modifications of this enzyme, (c) increased knowledge of the assembly process, and (d) facile methods for gene replacement in both the chloroplast and the nucleus may be necessary for success. Also, chloroplast genetic engineering is an exciting field of research. It has several advantages over other genetic engineering techniques, among which are high levels of foreign gene expression, transgene containment, reduced cellular toxicity of the foreign proteins, lack of gene silencing or position effects that are current concerns of nuclear genetic engineering. It is an environmentally friendly approach and has been successfully used to engineer several valuable plant traits such as herbicide, disease and insect resistance, drought and salt tolerance, and phytoremedition. In the past, chloroplast transformation had been successful in only a few crops, including tobacco, potato and tomato. More recently, highly efficient soybean, carrot, and cotton plastid transformation has been achieved via somatic embryogenesis using species-specific vectors. In addition to biotechnological applications, plastid transformation has also been extensively used to study chloroplast biochemistry and molecular biology. Recent advances and future challenges will be addressed.

Table of Content

Constantin A. Rebeiz

Summary
Abbreviations
I. Introduction
II. Agricultural Productivity and Photosynthetic Efficiency
III. Molecular Basis of the Discrepancy between the Theoretical Maximal Efficiency of the Photoelectron Transport System and the Actual Solar Conversion Efficiency of Photosynthesis under Field Conditions
IV. Correction of the Antenna/Photosystem Chlorophyll Mismatch
V. What kind of Scientific Knowledge is Needed to Bioengineer a Reduction in Photosynthetic Unit Size?
Epilogue
Acknowledgments
References

Vladimir L. Kolossov, and Constantin A. Rebeiz

Summary
I. Introduction
II. Materials and Methods
III. Results
IV. Discussion
Acknowledgments
References

Bernhard Grimm

Summary
Abbreviations
I. Inroduction
II. Mg protoporphyrin IX chelatase
III.S-Adenosyl-L-Methionine: Mg Protoporphyrin IX Methyltransferase
IV. Mg protoporphyrin monomethylester cyclase
V.Divinyl reductase
VI. Regulatory aspects of Mg porphyrin synthesis
References

Ryouichi Tanaka, Hisashi Ito and Ayumi Tanaka

Summary
I. Introduction
II. Pathway and enzymes of the chlorophyll cycle
III. Diversity and evolutionary aspects of the chlorophyll cycle
IV. Regulation of the chlorophyll cycle
Epilogue
Acknowledgements
References

C. Gamini Kannangara and Diter von Wettstein

Summary
Abbreviations
I. Introduction
II. The 40kDa Subunit
III. Comparision of the 40kDa Subunit with the Golgi Membrane Protein NSF-D2, Heat Shock Locus Protein HslU and the d' Subunit of the DNA Polymerase III (PolIII-d')
IV. The 70 kDa subunit and its Complex Formation with the 40 kDa Subunit
V. The 140 kDa Subunit
VI. The Gun Protein
Acknowledgments
References

William A. Cramer, Jiusheng Yan, E. Yamashita and Sergei Savikhin

Summary
Abbreviations
I. Introduction: on the Presence of Two Pigment Molecules in the Cytochrome b6f Complex
II. Crystal Structures of the b6f Complex; the Environment of the Bound Chlorophyll
III. Additional Function(s) of the Bound Chlorophyll
IV. Additional Function of the b-Carotene
Acknowledgments
References

Hartmut K. Lichtenthaler

Summary
Abbreviations
I. Introduction
II. The cytosolic acetate/ MVA pathway of 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 alga 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
Conclusion
Acknowledgements
References

Albert Boronat

Summary
Abbreviations
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
Acknowledgements
References

Esther Gerber, Andréa Hemmerlin, Dring N. Crowell, Michel Rohmer and Thomas J. Bach

Summary
I. Introduction
II. Protein Isoprenylation in Plants
III .Conclusions and Perspectives
References

Dinesh A. Nagegowda, David Rhodes, and Natalia Dudareva

Summary
I. Introduction
II. The Methyl erythritol phosphate (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
Acknowledgements
References

Henry E. Valentin1, Qungang Qi

Summary
I. IntroductionTocochromanol biosynthesis and regulation
II. Tocochromanol pathway engineering for enhancement of vitamin E
III. Optimized tocochromaol composition
IV. Enhancement of total tocochromanol content
V. Enhancement of tocotrienol biosynthesis
VI. Conclusions and outlook

Christoph Benning

Summary/Abbreviations
I. Introduction
II. Biosynthesis of Plastid 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
Acknowledgements
References

Yuki Nakamura, Koichi Kobayashi, Mie Shimojima and Hiroyuki Ohta

Summary
Abbreviations
I. Introduction
II. Identification of MGDG synthase in seed plants
III. Biochemical properties of MGDG synthase
IV. Function and regulation of MGDG synthase
V. Substrate supply systems for MGDG synthesis
VI. MGDG synthesis in photoautotrophic prokaryotes
VII. Future perspectives
Acknowledgements
References

Peter Dörmann

Summary
Abbreviations
I. Introduction
II. Structure and occurrence of digalactosyldiacylglycerol
III. Synthesis of digalactosyldiacylglycerol and oligogalactolipids
IV. Functions of digalactosyldiacylglycerol in photosynthesis
V. Digalactosyldiacylglycerol as a surrogate for phospholipids
VI. Changes in galactolipid content during stress and senescence
VII. Conclusions
References

J. Kenneth Hoober, Laura L. Eggink, Min Chen and Anthony W. D. Larkum

Summary
I. Introduction
II. Coordination Chemistry of Chlorophylls and Ligands
III. Binding of Chlorophyll to Proteins
IV. Chlorophyll Assignments in Light-Harvesting Complex II
V. Chlorophyll b Synthesis and Light-Harvesting Complex II Assembly
VI. Chlorophyllide a Oxygenase
VII. Acknowledgments VIII. References

Harald Paulsen, Christoph Dockter, Aleksei Volkov and Gunnar Jeschke

Summary
Abbreviations
I. Introduction
II. Time-resolved Measurements of LHCIIb Assembly in Vitro
III. Concluding Remarks
Acknowledgments
References

N.D. Singh and H. Daniell

Summary
I. Introduction
II. Genome and organization
III. Concept of chloroplast transformation
IV. Advantages of Plastid transformation
V. Chloroplast transformation vectors and mode of transgenes integration into
chloroplast genome
VI. Methods of plastid transformation and recovery transplastomic plants
VII. Current status of plastid transformation
VIII. Application of chloroplast technology for agronomic traits
IX. Chloroplast-derived vaccine antigens
X. Chloroplast-derived therapeutic proteins
XI. Chloroplast-derived industrially valuable biomaterials
XII. Epilogue
Acknowledgements
References

Tracey A. Ruhlman, Jeffrey W. Cary and Kanniah Rajasekaran

Summary
I. Introduction
II. Yield and Resistance
III. Aspergillus flavus: managing a Food and Feed Safety Threat
IV. The Case for Transgenic Interventions
V. Plastid Transformation: An Alternative Approach for Biotechnological Improvement
VI. Identifying Candidate Genes for Aflatoxin Resistance
VII . An Environmentally Benign Approach
VIII Future Challenges: Control of Aflatoxin Contamination in Cottonseed
IX Conclusion
Acknowledgments
References

Robert E. Sharwood and Spencer M. Whitney

Summary
I. Introduction
II. Transforming the Tobacco Plastome with Sunflower Rubisco Genes
III. Inadvertent Gene Excision by Recombination of Duplicated psbA 3'UTR Sequence
IV. Simple Removal of aadA in T0 tRstSLA by Transient CRE Recombinase Expression.
V. Growth Phenotypes of the tobRst, tRstLA and tRstL Lines
VI. Expression of the Hybrid LsSt Rubisco in Mature Leaves
VII. Whole Leaf Gas Exchange Measurements of the LsSt Kinetics
VIII. Future Considerations for Transplanting Foreign Rubiscos into Tobacco Plastids
IX Quicker Screening of the Assembly and Kinetics of Genetically Modified L8S8 Enzymes in Tobacco Chloroplasts.
Epilogue
Acknowledgements
References

Genhai Zhu, Itzhak Kurek and Lu Liu

Summary
Abbreviations
I. Introduction
II. Potential Targets for Improving Plant Photosynthesis
III. Directed Molecular Evolution Provides a Useful Tool to Engineer Targeted Enzymes
IV. Improving Rubisco Catalytic Efficiency by Gene Shuffling
V. Improving Rubisco Activase Thermostability by Gene Shuffling
VI. Future Prospects
Acknowledgements
References

Ruth Grene, Pinghua Li and Hans J Bohnert

Summary
Abbreviations
I. Introduction
II. Regulation of the photosynthetic apparatus: metabolic and environmental signals
III. Possible scenarios explaining effects of elevated [CO2] and [O3] on plant behavior in the altered earth atmosphere
IV. Benefits from Model Species – Arabidopsis thaliana and Thellungiella halophila
V. Discussion
VI. Conclusions
Acknowledgments
References

Toshiharu Shikanai

Summary
Abbreviations
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
Concluding Remarks
Acknowledgements
References

Yoshihiko Nanasato, Chikahiro Miyake, Kentaro Takahara, Kaori Kohzuma, Yuri Nakajima Munekage, Akiho Yokota and Kinya Akashi

Summary
I. Introduction
II. Experimental procedures
III. Physiological responses 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
Acknowledgements
References

Anchalee Sirikhachornkit and Krishna K. Niyogi

Summary
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
VII. Enzymatic Mechanisms for Scavenging Reactive Oxygen Species
Acknowledgments
References

Baishnab C. Tripathy and Gopal K. Pattanayak

Summary
Abbreviations
I. Introduction
II. Formation of Singlet Oxygen in Plants
III. Generation of Singlet Oxygen from Chlorophyll Biosynthesis Intermediates
IV. Porphyrin-generating Compounds
V. Type I and Type II Photosensitization Reactions of Tetrapyrroles
VI Intracellular Destruction of Singlet Oxygen
VII Oxygen- mediated Oxidative Damage to the Photosynthetic Apparatus
VII. Effect of Singlet Oxygen on Thermoluminiscence
VIII. Singlet Oxygen-induced Oxidative Damage in Mutants
IX. Future Prospects
Acknowledgements
References