Bioenergy Feedstocks E-Book

• Herausgeber: John Wiley & Sons
• Kategorie: Wissenschaft und neue Technologien
• Sprache: Englisch

Seitenzahl: 638

Veröffentlichungsjahr: 2013

Beschreibung

Bioenergy and biofuels are generated from a wide variety of feedstock. Fuels have been converted from a wide range of sources from vegetable oils to grains and sugarcane. Second generation biofuels are being developed around dedicated, non-food energy crops, such as switchgrass and Miscanthus, with an eye toward bioenergy sustainability.  Bioenergy Feedstocks: Breeding and Genetics looks at advances in our understanding of the genetics and breeding practices across this diverse range of crops and provides readers with a valuable tool to improve cultivars and increase energy crop yields.

Bioenergy Feedstocks: Breeding and Genetics opens with chapters focusing primarily on advances in the genetics and molecular biology of dedicated energy crops. These chapters provide in-depth coverage of new, high-potential feedstocks. The remaining chapters provide valuable overview of breeding efforts of current feedstocks with specific attention paid to the development of bioenergy traits. Coverage in these chapters includes crops such as sorghum, energy canes, corn, and other grasses and forages.

The final chapters explore the role of transgenics in bioenergy feedstock production and the development of low-input strategies for producing bioenergy crops. A timely collection of work from a global team of bioenergy researchers and crop scientists, Bioenergy Feedstocks: Breeding and Genetics is an essential reference on cultivar improvement of biomass feedstock crops.

Leseprobe

Contents

Cover

Title Page

Copyright

The Editors

List of Contributors

Preface

Chapter 1: Introduction

1.1 Historical Development

1.2 Cultivar Development

1.3 Breeding Approach

1.4 Molecular Tools

1.5 Future Outlook

References

Chapter 2: Switchgrass Genetics and Breeding Challenges

2.1 Introduction

2.2 Origin and Distribution

2.3 Growth and Development, Genome Structure and Cytogenetics

2.4 Genetic Diversity

2.5 Phenotypic Variability and Inheritance

2.6 Conventional Breeding Approaches

2.7 Molecular Breeding

2.8 Conclusions and Future Directions

References

Chapter 3: Switchgrass Genomics

3.1 Introduction

3.2 Genome Sequencing

3.3 Analysis of Expressed Sequences in Switchgrass

3.4 Linkage Mapping

3.5 Cytoplasmic Genome

3.6 Genome-enabled Improvement of Switchgrass

3.7 Conclusions

References

Chapter 4: Germplasm Resources of Miscanthus and Their Application in Breeding

4.1 Introduction

4.2 Species Belonging to Miscanthus Genus, Their Characteristics, and Phylogenetic Relationships

4.3 Natural Hybrids between Miscanthus Species

4.4 Karyotype Analysis

4.5 Phylogenetic Relationships between Miscanthus Species

4.6 Genetic Improvement of Miscanthus

4.7 Variations in Several Agronomical Traits Related to Yield and Plant Performance

4.8 Molecular Resources

4.9 Transgenic Miscanthus

4.10 Future Studies

References

Chapter 5: Breeding Miscanthus for Bioenergy

5.1 Introduction

5.2 Miscanthus as a Biomass Crop

5.3 Breeding Strategy

5.4 Genetic Diversity

5.5 Breeding Targets

5.6 Incorporating Bioinformatics, Molecular Marker-Assisted Selection (MAS), and Genome-Wide Association Studies (GWAS)

5.7 Summary

Acknowledgments

References

Chapter 6: Breeding Sorghum as a Bioenergy Crop

6.1 Introduction

6.2 Botanical Description and Evolution

6.3 Traditional Breeding and Development

6.4 Approaches to Breeding Sorghum as a Bioenergy Crop

6.5 Composition in Energy Sorghum Breeding

6.6 Genetic Variation and Inheritance

6.7 Wide Hybridization

6.8 Conclusions

References

Chapter 7: Energy Cane

7.1 Introduction

7.2 Sugar and Energy Production Systems

7.3 Sugarcane Improvement

7.4 Selection of Sugarcane Genotypes for Energy Production

7.5 Conclusion

Acknowledgments

References

Chapter 8: Breeding Maize for Lignocellulosic Biofuel Production

8.1 Introduction

8.2 General Attributes of Maize as a Biofuel Crop

8.3 Potential Uses of Maize Stover for Bioenergy

8.4 Breeding Maize for Biofuels

8.5 Single Genes and Transgenes

8.6 Future Outlook

References

Chapter 9: Underutilized Grasses

9.1 Introduction

9.2 Prairie Cordgrass

9.3 Bluestems

9.4 Eastern Gamagrass

References

Chapter 10: Alfalfa as a Bioenergy Crop

10.1 Introduction

10.2 Biomass for Biofuels

10.3 Why Alfalfa?

10.4 Breeding Strategies

10.5 Breeding Targets

10.6 Management and Production Inputs

10.7 Processing for Biofuels

10.8 Additional Value from Alfalfa Production

10.9 Summary

Acknowledgments

References

Chapter 11: Transgenics for Biomass

11.1 Introduction

11.2 Transgenic Approaches

11.3 Transgenic Approaches for Biomass Improvement

11.4 Summary

Acknowledgments

References

Chapter 12: Endophytes in Low-input Agriculture and Plant Biomass Production

12.1 Introduction

12.2 What are Endophytes?

12.3 Endophytes of Cool Season Grasses

12.4 Endophytes of Warm Season Grasses

12.5 Endophytes of Woody Angiosperms

12.6 Other Fungal Endophytes

12.7 Endophytes in Biomass Crop Production

12.8 The Use of Fungal Endophytes in Bioenergy Crop Production Systems

12.9 Endophyte Consortia

12.10 Source of Novel Compounds

12.11 Endophyte in Genetic Engineering of Host Plants

12.12 Conclusions

Acknowledgments

References

Index

This edition first published 2013 © 2013 by John Wiley & Sons, Inc.

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The Editors

Malay C. SahaForage Improvement Division (FID) The Samuel Roberts Noble Foundation, Inc. Ardmore, [email protected] S. BhandariDepartment of Plant Sciences University of Tennessee Knoxville, [email protected] H. BoutonForage Improvement Division (FID) The Samuel Roberts Noble Foundation, Inc. Ardmore, [email protected]

List of Contributors

Laura BartleyDepartment of Botany and Microbiolgy University of Oklahoma Norman, OKKishor BhattaraiForage Improvement Division The Samuel Roberts Noble Foundation Ardmore, OKArvid BoeSouth Dakota State University Brookings, SDJohn Clifton BrownInstitute of Biological, Environmental and Rural Sciences (IBERS) Aberystwyth University Gogerddan, Aberystwyth, Ceredigion, Wales, UKE. Charles BrummerForage Improvement Division The Samuel Roberts Noble Foundation Ardmore, OKKelly D. CravenPlant Biology Division The Samuel Roberts Noble Foundation Ardmore, OKChris DaveyInstitute of Biological, Environmental and Rural Sciences (IBERS) Aberystwyth University Gogerddan, Aberystwyth, Ceredigion, Wales, UKNatalia de LeonDepartment of Agronomy University of Wisconsin Madison, WIIain DonnisonInstitute of Biological, Environmental and Rural Sciences (IBERS) Aberystwyth University Gogerddan, Aberystwyth, Ceredigion, Wales, UKMaria Stefanie DwiyantiEnergy Biosciences Institute University of Illinois Urbana, ILKerrie FarrarInstitute of Biological, Environmental and Rural Sciences (IBERS) Aberystwyth University Gogerddan, Aberystwyth, Ceredigion, Wales, UKSita R. GhimireCenter for Agricultural and Environmental Biotechnology RTI International Research Triangle Park, NCJ. Gonzalez-HernandezSouth Dakota State University Brookings, SDC. Frank HardinForage Improvement Division The Samuel Roberts Noble Foundation Ardmore, OKCharlotte HayesInstitute of Biological, Environmental and Rural Sciences (IBERS) Aberystwyth University Gogerddan, Aberystwyth, Ceredigion, Wales, UKMaurice Hinton-JonesInstitute of Biological, Environmental and Rural Sciences (IBERS) Aberystwyth University Gogerddan, Aberystwyth, Ceredigion, Wales, UKLin HuangInstitute of Biological, Environmental and Rural Sciences (IBERS) Aberystwyth University Gogerddan, Aberystwyth, Ceredigion, Wales, UKElaine JensenInstitute of Biological, Environmental and Rural Sciences (IBERS) Aberystwyth University Gogerddan, Aberystwyth, Ceredigion, Wales, UKPhillips JacksonCSIRO Plant Industry Australian Tropical Science Innovation Precinct Townsville, AustraliaLaurence JonesInstitute of Biological, Environmental and Rural Sciences (IBERS) Aberystwyth University Gogerddan, Aberystwyth, Ceredigion, Wales, UKShawn M. KaepplerDepartment of Agronomy University of Wisconsin Madison, WIJoe G. LauerDepartment of Agronomy University of Wisconsin Madison, WID. K. LeeUniversity of Illinois Urbana, ILAnne MaddisonInstitute of Biological, Environmental and Rural Sciences (IBERS) Aberystwyth University Gogerddan, Aberystwyth, Ceredigion, Wales, UKHeike MeyerJulius Kühn-Institute (JKI) Federal Research Centre for Cultivated Plants Bundesallee, GermanyMaria J. MonterosForage Improvement Division The Samuel Roberts Noble Foundation Ardmore, OKJohn NorrisInstitute of Biological, Environmental and Rural Sciences (IBERS) Aberystwyth University Gogerddan, Aberystwyth, Ceredigion, Wales, UKSarah PurdyInstitute of Biological, Environmental and Rural Sciences (IBERS) Aberystwyth University Gogerddan, Aberystwyth, Ceredigion, Wales, UKA. Lane RayburnUniversity of Illinois Urbana, ILPaul RobsonInstitute of Biological, Environmental and Rural Sciences (IBERS) Aberystwyth University Gogerddan, Aberystwyth, Ceredigion, Wales, UKW. L. RooneyDepartment of Soil and Crop Sciences Texas A&M University College Station, TexasAaron SaathoffGrain, Forage, and Bioenergy Research Unit USDA-ARS and Department of Agronomy and Horticulture University of Nebraska Lincoln, NECosentino SalvatoreDepartment of Agriculture and Food Science University of Catania Via Valdisavoia, Catania, ItalyGautam SarathGrain, Forage, and Bioenergy Research Unit USDA-ARS and Department of Agronomy and Horticulture University of Nebraska Lincoln, NEKai-Uwe SchwarzJulius Kühn-Institute (JKI) Federal Research Centre for Cultivated Plants Bundesallee, Braunschweig, GermanyGancho SlavovInstitute of Biological, Environmental and Rural Sciences (IBERS) Aberystwyth University Gogerddan, Aberystwyth, Ceredigion, Wales, UKTim SpringerSouthern Plains Range Research Station Woodward, OKT. R. StefaniakDepartment of Soil and Crop Sciences Texas A&M University College Station, TXJ. Ryan StewartBrigham Young University Provo, UTCharlie RodgersCeres, Inc. Somerville, TXChristian TobiasUSDA-ARS Western Regional Research Center Albany, CAJohn ValentineInstitute of Biological, Environmental and Rural Sciences (IBERS) Aberystwyth University Gogerddan, Aberystwyth, Ceredigion, Wales, UKZeng-Yu WangForage Improvement Division The Samuel Roberts Noble Foundation Ardmore, OKRichard WebsterInstitute of Biological, Environmental and Rural Sciences (IBERS) Aberystwyth University Gogerddan, Aberystwyth, Ceredigion, Wales, UKYanqi WuDepartment of Plant and Soil Science Oklahoma State University Stillwater, OKToshihiko YamadaField Science Center for Northern Biosphere Hokkaido University Kita-ku, Sapporo, Hokkaido, JapanSue YouellInstitute of Biological, Environmental and Rural Sciences (IBERS) Aberystwyth University Gogerddan, Aberystwyth, Ceredigion, Wales, UK

Preface

The world energy use grew by 39% from 1990 to 2008. It is estimated that the global demand for energy will increase by at least 50% over the next 20 years. Energy consumption growth of several developing nations remains vigorous. Hydrocarbons, petroleum, coal, and natural gas are now the chief sources of energy. All are finite resources and their natural reserves are depleting every day. In addition, during their conversion and use several greenhouse gases are emitted with a potential for climatic warming.

Bioenergy, both biofuels and biopower, produced from renewable sources are sustainable alternatives to hydrocarbons. Bioenergy use has the potential to lower greenhouse gas emissions, boost rural economy, and ensure energy security. Interest in bioenergy began in early 20th century but it was reinforced in the recent decades. Biopower includes co-firing bioenergy feedstocks with coal to reduce problem emissions. Due to government incentives during 1995–2005, commercial scale biofuels, mainly ethanol, became available in the European Union, UK, USA, Brazil, and many other countries around the world. Most of the biofuels are derived from corn grain, sugarcane, and vegetable oil feedstocks thus creating a food versus fuel controversy. Second-generation biofuels are now being made from nonfood, lignocellulosic materials such as municipal waste and wood chips, along with dedicated crops such as switchgrass and Miscanthus.

Plant breeding is critical for crop improvement. Due to intensive breeding efforts in both public and private sectors average maize grain yield has increased by 745% since 1930. Several of the dedicated feedstock crops, for example, switchgrass and Miscanthus, are only recently removed from the wild and need serious breeding efforts for improvement. Increased biomass yield and improved quality through breeding efforts can make feedstock more economical and attractive. This book on Bioenergy Feedstocks: Breeding and Genetics should greatly contribute to these breeding efforts.

We are grateful to John Wiley & Sons, Inc. for their prudence and supporting us in publishing this book. Contribution from many prominent scientists on bioenergy research has greatly enhanced this publication. We extend our sincere appreciation to all the chapter contributors for their invaluable contribution. We also appreciate the efforts of all who directly or indirectly supported our endeavor. We sincerely believe that this book will be a useful reference for cultivar improvement of lignocellulosic biomass feedstock crops.

Malay C. SahaHem S. BhandariJoseph H. Bouton

Chapter 1

Introduction

Joseph H. Bouton1, Hem S. Bhandari2 and Malay C. Saha3

1Former Director and Senior Vice President, Forage Improvement Division, The Samuel Roberts Noble Foundation, Ardmore, OK 73401 and Emeritus Professor, Crop and Soil Sciences, University of Georgia, Athens, GA 30602, USA2Department of Plant Sciences, University of Tennessee, Knoxville, TN37996, USA3Forage Improvement Division, The Samuel Roberts Noble Foundation, Ardmore, OK 73401, USA

By most estimates, world population growth has more than tripled during the past 100 years, going from approximately 2–7 billion persons (Anonymous, 2012). To sustain the economies needed to support this type of unprecedented population growth, readily available, cheap, scalable, and efficient energy sources were required. These sources turned out to be hydrocarbons, both oil and coal, and after the Second World War, nuclear power. Heavy hydrocarbon use resulted in their depletion and increased cost and a concurrent increase in environmental problems due to gas emissions. Although “clean” as far as gas emissions, nuclear power has its own problems associated with safety and disposal of its highly toxic waste products. Therefore, alternative energy sources such as wind, solar, and bioenergy that are capable of offsetting some of the hydrocarbons and nuclear use and mitigating their environmental problems are now being investigated and, in some cases, implemented on a commercial scale.

Lignocellulosic feedstocks derived from plant biomass emerged as a sustainable and renewable energy source that underpins the bioenergy industry (McLaughlin, 1992; Sanderson et al., 2006). Bioenergy, both biopower and biofuels, could contribute significantly to meet growing energy demand while mitigating the environmental problems. The Energy Independence and Security Act RFS2 in the United States mandates that annual biofuels' use increase to 36 billion gallons per year by 2022, of which 21 billion gallons should come from advanced biofuels (EISA, 2007). Waste products, both agricultural and forest residues, are obvious choices as base feedstocks; however, it is the use of “dedicated” energy crops where the ability to achieve the billion tons of biomass USA goals will be realized (Perlack et al., 2005). Several plant species such as switchgrass, Miscanthus, corn fodder, sorghum, energy canes, and other grass and legume species have demonstrated tremendous potential for use as dedicated bioenergy feedstocks especially for the production of advanced biofuels. Their adaptation patterns along most agro-ecological gradients also offer options for optimizing a crop species mix for any bioenergy feedstock production system.

1.1 Historical Development

The concept of bioenergy is not new. Early human civilization witnessed energy potential of plant biomass and used it in cooking and as a source of light. By 1912, Rudolf Diesel demonstrated that diesel obtained from plant biomass can be used in automobile operation (Korbitz, 1999). The shortage of crude oil during the 1970s reinforced the world's motivation toward plant biomass as alternative energy source. In Brazil, use of ethanol to power automobile dates back to the late 1920s. Brazil's National Alcohol Program under government funding was launched in 1975 to promote ethanol production from sugarcane. In 2007, Brazil produced more than 16 billion liters of ethanol (Goldemberg, 2007).

In the United States, during the past decade, billions of dollars were invested annually by the federal and state governments, venture capitalists, and major private companies for the development of new technology to convert feedstock species into renewable biofuels. Major breakthroughs have happened during the past few years and the biofuel production increased significantly. Significant improvements have also noticed on conversion technologies thus moving the biofuel from pilot scale to near-commercial scale.

At present, biofuels are produced from corn grain, sugar cane, and vegetable oil. In the United States, corn is the main feedstock used to produce ethanol. In 2010, corn-based ethanol production was about 50 billion liters (USDOE, 2011). With the increasing world's food demand there is serious economic (animal feed costs are rising) and even ethical concern with using corn grain in ethanol production. In the mid-1985s, U.S. Department of Energy (DOE) Herbaceous Energy Crops Program (HECP), coordinated by Oakridge National Laboratory (ORNL), funded research to identify potential herbaceous species as potential bioenergy feedstock. Over 30 plant herbaceous crop species including grasses and legumes were studied, and consequently switchgrass was chosen as the “model bioenergy species” (McLaughlin and Kszos, 2005). Under optimum conditions, switchgrass demonstrated annual biomass yield as high as 24 Mg ha−1, and each ton of biomass can produce about 380 L of ethanol (Schmer et al., 2008). Carbon sequestration by 5-year-old switchgrass stand can add 2.4 Mg C ha−1 year−1 for 10,000 Mg ha−1 of soil mass (Schmer et al., 2011). Other plant species with high bioenergy potential include Miscanthus, corn fodder, sorghum, sugarcane, prairie cordgrass, bluestems, eastern gamagrass, and alfalfa. Miscanthus hybrids have the potential to produce high biomass and can make a significant contribution to biofuel production and to the mitigation of climate change. Plant breeding will play an important role in improving the genetic potential of these species, as well as other potential species, and make them suitable as bioenergy feedstock.

1.2 Cultivar Development

Genetic improvement of plant species targeting biomass feedstock production, particularly the dedicated energy crops such as switchgrass and Miscanthus, is in a very early stage, posing both challenges and opportunities for genetic improvement. The current emphasis of most biomass feedstock cultivar development research is based on biomass yield. Due to extensive breeding efforts, maize grain yield has increased 745% from 1930 to the present (USDA-NASS, 2011). Biomass yield per unit of land is a function of many traits; thus plant breeders also have to address problems related to establishment, seed shattering, and resistance to abiotic/biotic stresses. Equally important is improvement in feedstock quality for sustainable bioeconomy. Research is still evolving on processes to convert biomass to bioenergy/biofuel that will dictate the quality targets of dedicated bioenergy crops. One likely scenario is that both enzymatic and thermochemical conversion technologies will be required depending on the biomass feedstock availability and the targeted bioenergy end product.

1.3 Breeding Approach

The fundamentals of feedstock cultivar development will be the same as ones that have been successfully employed in several agricultural crops for thousands of years. Most of the potential bioenergy crops are outcrossing polyploids and great genetic diversity exists both within and among populations. This reinforces the potential for genetic improvement of these crops. Most of the named switchgrass cultivars were developed only by seed increases of desirable plants identified from the wild or selected through two or three generations under cultivation (Casler et al., 2007). The improvement of quantitative traits will require several cycles of selection (Bouton, 2008). The traits that are qualitatively inherited can be improved rapidly. Exploitation of heterosis would require identification of genes involved in heterosis and development of heterotic pools, similar to the one that was followed in hybrid breeding in maize. Different crop species would need different plant breeding methodologies depending on their mode of reproduction, ploidy systems, and germplasm availability. For example, corn has a well-developed hybrid production system using inbred lines, which may not be directly applicable to crops like switchgrass that has nearly 100% self-incompatibility. Some species of Miscanthus and sugarcane that do not produce seeds require a different approach. The hundreds of years of experience gained in the development of modern cultivars of food and other agricultural crops can directly benefit the cultivar development research of bioenergy crops.

1.4 Molecular Tools

Rapid development in high-throughput genotyping, genotyping based on sequencing, and computational biology continues to shape modern plant breeding into a new approach called “molecular breeding.” Rapid discoveries of DNA-based markers at significantly reduced cost have impacted cultivar development methodologies in the recent years. Advances in molecular biological research have uncovered several plant biological functions and enhanced the understanding of gene function at the molecular level (Bouton, 2008). Rapidly growing genome, transcriptome, proteome, and metabolom resources of several important biofuel crops can speed the process of feedstock development which can lead to improved economics of renewable bioenergy production. Lignin polymer is found to be interfering with enzymatic digestion of lignocellulosic biomass necessitating the pretreatment of biomass feedstock, making biofuel production an economic challenge (Dien et al., 2011). However, plant biologists have been able to characterize and modify lignin pathway and produce low lignin plants by silencing genes involved in lignin pathway (Dien et al., 2011; Fu et al., 2011). Transgenic technologies have also enabled plant breeders to look beyond target species for genes conferring desirable traits, but current regulatory aspects could curtail gains from transgenics, especially for bioenergy crops, without deregulation reforms that better balance both risk and benefit (Strauss et al., 2010).

1.5 Future Outlook

Changing climates as seen by frequent unprecedented drought cycles have become a serious challenge in the recent decades. This will require an “adjustment philosophy” in that breeding strategies will need to continually adjust trait targets for greater stress extremes with programs concentrating on stress tolerances growing in importance (Bouton, 2010). As biomass feedstock production scales up to a commercial level, there will also be a significant shift in agricultural landscapes, leading to occurrence of new pest and diseases specific to the feedstock species. Exploration and exploitation of microbial endophytes implicated in protection of plants from a broad range of biotic and abiotic stresses are important areas for future research (Ghimire et al., 2011). Bioenergy crop breeders should therefore take proactive action to integrate all conventional and modern tools into their cultivar development research.

There are government policy issues that may assist the growth of bioenergy industry. However, these are political issues not within the scope of this book and will need to be hashed out at that level. But one thing is certain, bioenergy cultivar development research will benefit by always striving for a cost-effective product that competes in the free market with hydrocarbons and nuclear power. This should become more possible by leveraging facilities/resources established for traditional agricultural crops and implementation of regional/national/international collaborations between institutions involved in bioenergy feedstock research. Finally, sharing germplasms between participating institutes would help maintain genetic diversity of the breeding pools needed for long-term use.

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