Plant Genes, Genomes and Genetics

Plant Genes, Genomes and Genetics provides a comprehensive treatment of all aspects of plant gene expression. Unique in explaining the subject from a plant perspective, it highlights the importance of key processes, many first discovered in plants, that impact how plants develop and interact with the environment. This text covers topics ranging from plant genome structure and the key control points in how genes are expressed, to the mechanisms by which proteins are generated and how their activities are controlled and altered by posttranslational modifications. Written by a highly respected team of specialists in plant biology with extensive experience in teaching at undergraduate and graduate level, this textbook will be invaluable for students and instructors alike. Plant Genes, Genomes and Genetics also includes: specific examples that highlight when and how plants operate differently from other organisms special sections that provide in-depth discussions of particular issues end-of-chapter problems to help students recapitulate the main concepts rich, full-colour illustrations and diagrams clearly showing important processes in plant gene expression a companion website with PowerPoint slides, downloadable figures, and answers to the questions posed in the book Aimed at upper level undergraduates and graduate students in plant biology, this text is equally suited for advanced agronomy and crop science students inclined to understand molecular aspects of organismal phenomena. It is also an invaluable starting point for professionals entering the field of plant biology.

Table of Contents:
Acknowledgements xi Introduction xiii About the Companion Website xix PART I: PLANT GENOMES AND GENES Chapter 1 Plant genetic material 3 1.1 DNA is the genetic material of all living organisms, including plants 3 1.2 The plant cell contains three independent genomes 8 1.3 A gene is a complete set of instructions for building an RNA molecule 10 1.4 Genes include coding sequences and regulatory sequences 11 1.5 Nuclear genome size in plants is variable but the numbers of protein-coding, non-transposable element genes are roughly the same 12 1.6 Genomic DNA is packaged in chromosomes 15 1.7 Summary 15 1.8 Problems 15 References 16 Chapter 2 The shifting genomic landscape 17 2.1 The genomes of individual plants can differ in many ways 17 2.2 Differences in sequences between plants provide clues about gene function 20 2.3 SNPs and lengthmutations in simple sequence repeats are useful tools for genome mapping and marker assisted selection 22 2.4 Genome size and chromosome number are variable 28 2.5 Segments of DNA are often duplicated and can recombine 30 2.6 Some genes are copied nearby in the genome 31 2.7 Whole genome duplications are common in plants 34 2.8 Whole genome duplication has many effects on the genome and on gene function 37 2.9 Summary 41 2.10 Problems 42 Further reading 42 References 42 Chapter 3 Transposable elements 45 3.1 Transposable elements are common in genomes of all organisms 45 3.2 Retrotransposons are mainly responsible for increases in genome size 46 3.3 DNA transposons create small mutations when they insert and excise 52 3.4 Transposable elements move genes and change their regulation 57 3.5 How are transposable elements controlled? 60 3.6 Summary 60 3.7 Problems 61 References 61 Chapter 4 Chromatin, centromeres and telomeres 63 4.1 Chromosomes are made up of chromatin, a complex of DNA and protein 63 4.2 Telomeres make up the ends of chromosomes 66 4.3 The chromosome middles–centromeres 71 4.4 Summary 77 4.5 Problems 77 Further reading 77 References 77 Chapter 5 Genomes of organelles 79 5.1 Plastids and mitochondria are descendants of free-living bacteria 79 5.2 Organellar genes have been transferred to the nuclear genome 80 5.3 Organellar genes sometimes include introns 82 5.4 Organellar mRNA is often edited 82 5.5 Mitochondrial genomes contain fewer genes than chloroplasts 84 5.6 Plant mitochondrial genomes are large and undergo frequent recombination 87 5.7 All plastid genomes in a cell are identical 91 5.8 Plastid genomes are similar among land plants but contain some structural rearrangements 93 5.9 Summary 95 5.10 Problems 95 Further reading 95 References 95 PART II: TRANSCRIBING PLANT GENES Chapter 6 RNA 99 6.1 RNA links components of the Central Dogma 99 6.2 Structure provides RNA with unique properties 102 6.3 RNA has multiple regulatory activities 105 6.4 Summary 108 6.5 Problems 108 References 109 Chapter 7 The plant RNA polymerases 111 7.1 Transcription makes RNA from DNA 111 7.2 Varying numbers of RNA polymerases in the different kingdoms 112 7.3 RNA polymerase I transcribes rRNAs 114 7.4 RNA polymerase III recruitment to upstream and internal promoters 116 7.5 Plant-specific RNP-IV and RNP-V participate in transcriptional gene silencing 117 7.6 Organelles have their own set of RNA polymerases 117 7.7 Summary 118 7.8 Problems 118 References 118 Chapter 8 Making mRNAs – Control of transcription by RNA polymerase II 121 8.1 RNA polymerase II transcribes protein-coding genes 121 8.2 The structure of RNA polymerase II reveals how it functions 121 8.3 The core promoter 123 8.4 Initiation of transcription 125 8.5 The mediator complex 127 8.6 Transcription elongation: the role of RNP-II phosphorylation 128 8.7 RNP-II pausing and termination 129 8.8 Transcription re-initiation 130 8.9 Summary 130 8.10 Problems 130 References 130 Chapter 9 Transcription factors interpret cis-regulatory information 133 9.1 Information on when, where and how much a gene is expressed is codified by the gene’s regulatory regions 133 9.2 Identifying regulatory regions requires the use of reporter genes 134 9.3 Gene regulatory regions have a modular structure 135 9.4 Enhancers: Cis-regulatory elements or modules that function at a distance 137 9.5 Transcription factors interpret the gene regulatory code 138 9.6 Transcription factors can be classified in families 138 9.7 How transcription factors bind DNA 139 9.8 Modular structure of transcription factors 143 9.9 Organization of transcription factors into gene regulatory grids and networks 146 9.10 Summary 146 9.11 Problems 146 More challenging problems 147 References 147 Chapter 10 Control of transcription factor activity 149 10.1 Transcription factor phosphorylation 149 10.2 Protein–protein interactions 151 10.3 Preventing transcription factors from access to the nucleus 155 10.4 Movement of transcription factors between cells 156 10.5 Summary 158 10.6 Problems 158 References 158 Chapter 11 Small RNAs 161 11.1 The phenomenon of cosuppression or gene silencing 161 11.2 Discovery of small RNAs 162 11.3 Pathways for miRNA formation and function 163 11.4 Plant siRNAs originate from different types of double-stranded RNAs 166 11.5 Intercellular and systemic movement of small RNAs 168 11.6 Role of miRNAs in plant physiology and development 170 11.7 Summary 171 11.8 Problems 171 References 172 Chapter 12 Chromatin and gene expression 173 12.1 Packing long DNA molecules in a small space: the function of chromatin 173 12.2 Heterochromatin and euchromatin 173 12.3 Histone modifications 174 12.4 Histone modifications affect gene expression 175 12.5 Introducing and removing histone marks: writers and erasers 175 12.6 ‘Readers’ recognize histone modifications 177 12.7 Nucleosome positioning 177 12.8 DNA methylation 178 12.9 RNA-directed DNA methylation 179 12.10 Control of flowering by histone modifications 180 12.11 Summary 181 12.12 Problems 181 References 181 PART III: FROM RNA TO PROTEINS Chapter 13 RNA processing and transport 185 13.1 RNA processing can be thought of as steps 185 13.2 RNA capping provides a distinctive 5’ end to mRNAs 185 13.3 Transcription termination consists of mRNA 3’-end formation and polyadenylation 189 13.4 RNA splicing is another major source of genetic variation 192 13.5 Export of mRNA from the nucleus is a gateway for regulating which mRNAs actually get translated 194 13.6 Summary 196 13.7 Problems 196 References 196 Chapter 14 Fate of RNA 199 14.1 Regulation of RNA continues upon export from nucleus 199 14.2 Mechanisms for RNA turnover 199 14.3 RNA surveillance mechanisms 201 14.4 RNA sorting 202 14.5 RNA movement 203 14.6 Summary 204 14.7 Problems 204 Further reading 205 References 205 Chapter 15 Translation of RNA 207 15.1 Translation: a key aspect of gene expression 207 15.2 Initiation 209 15.3 Elongation 209 15.4 Termination 210 15.5 Tools for studying the regulation of translation 211 15.6 Specific translational control mechanisms 211 15.7 Summary 213 15.8 Problems 214 Further reading 214 References 214 Chapter 16 Protein folding and transport 215 16.1 The pathway to a protein’s function is a complicated matter 215 16.2 Protein folding and assembly 215 16.3 Protein targeting 218 16.4 Co-translational targeting 218 16.5 Post-translational targeting 219 16.6 Post-translational modifications regulating function 220 16.7 Summary 222 16.8 Problems 223 Further reading 223 References 224 Chapter 17 Protein degradation 225 17.1 Two sides of gene expression–synthesis and degradation 225 17.2 Autophagy, senescence and programmed cell death 225 17.3 Protein-tagging mechanisms 226 17.4 The ubiquitin proteasome system rivals gene transcription 228 17.5 Summary 231 17.6 Problems 231 Further reading 231 Reference 231 Index 233

About the Author :
Dr Erich Grotewold is currently a professor in the Department of Molecular Genetics (College of Arts & Sciences) as well as in the Department of Horticulture & Crop Sciences (College of Food, Agriculture & Environmental Sciences) at The Ohio State University. His research focuses on plant systems biology. Dr Joseph Chappell joined the faculty at the University of Kentucky in 1985, where he has developed an internationally recognized research program pioneering the molecular genetics and biochemistry of natural products in plants. Dr Elizabeth A. Kellogg was formerly the E. Desmond Lee and Family Professor of Botanical Studies at the University of Missouri–St. Louis, and is currently a Member of the Donald Danforth Plant Science Center in St. Louis. Her work focuses on the evolution of plant genes, genomes and development, particularly in the cereal crops and their wild relatives.