Matthews Fundamentals of Plant Virology

1. Auflage 2012
ISBN: 978-0-323-13849-9
Verlag: Elsevier Science & Techn.
Format: EPUB
Kopierschutz: 6 - ePub Watermark

E-Book, Englisch, 403 Seiten

Fundamentals of Plant Virology is an introductory student text covering all of modern plant virology. The author, Dr. R.E.F. Matthews, has written this coursebook based on his classic and comprehensive Plant Virology, Third Edition. Four introductory chapters review properties of viruses and cells and techniques used in their study. Five chapters are devoted to current knowledge of all major plant viruses and related pathogens. Seven chapters describe biological properties such as transmission, host response, disease, ecology, control, classification, and evolution of plant viruses. A historical and future overview concludes the text. Fundamentals of Plant Virology is a carefully designed instructional format for a plant virology course. It is also an invaluable resource for students of plant pathology and plant molecular biology. - Summarizes knowledge on all aspects of plant virology - Condenses all essential material from Plant Virology 3/e - Compares basic properties of cells and viruses - Outlines principles of gene manipulation technology - Discusses serological techniques including monoclonal antibodies - Geared to student level course

Autoren/Hrsg.

Matthews, R C

Inhaltsverzeichnis

1;Front Cover;2
2;Fundamentals of Plant Virology;4
3;Copyright Page;5
4;Table of Contents;6
5;Preface;12
6;CHAPTER 1. What Are Viruses?;14
6.1;1 Viruses and Cells Compared;15
6.2;2 Definition of a Virus;21
6.3;Further Reading;23
7;CHAPTER 2. Principal Techniques for the Study of Virus Particle and Genome Structure;24
7.1;1 Structure of Virus Particles;25
7.2;2 The Structure of Viral Genomes;27
7.3;3 Amino Acid Sequences of Viral Proteins;41
7.4;4 mRNAs;41
7.5;5 Introduction of a DNA Step into the Life Cycle of RNA Plant Viruses;44
7.6;6 Transgenic Plants;47
7.7;7 The Polymerase Chain Reaction;48
7.8;Further Reading;49
8;CHAPTER 3. Serological Methods in Plant Virology;50
8.1;1 The Basis for Serological Tests;51
8.2;2 Methods for Detecting Antibody–Virus Combination;54
8.3;3 Monoclonal Antibodies;60
8.4;4 Serological Methods in the Study of Virus Structure;64
8.5;Further Reading;65
9;CHAPTER 4. Assay and Purification of Virus Particles;66
9.1;1 Assay;67
9.2;2 Purification;72
9.3;Further Reading;78
10;CHAPTER 5. Virus Structure;79
10.1;1 Physical Principles in the Architecture of Small Viruses;80
10.2;2 Examples of Plant Viruses with Different Kinds of Architecture;89
10.3;3 Interaction between RNA and Protein in Small Isometric Viruses;103
10.4;Further Reading;103
11;CHAPTER 6. Introduction to the Study of Virus Replication;104
11.1;1 General Properties of Plant Viral Genomes;106
11.2;2 Host Functions Used by Plant Viruses;116
11.3;3 Generalized Outline for the Replication of a Small ss-Positive Sense RNA Virus;118
11.4;4 Methods for Determining Genome Structure and Strategy;118
11.5;5 The Regulation of Virus Production;127
11.6;6 Experimental Systems for Studying Viral Replication in Vivo;133
11.7;7 Errors in Virus Replication;135
11.8;Further Reading;136
12;CHAPTER 7. Replication of Viruses with ss-Positive Sense RNA Genomes;137
12.1;1 The Potyvirus Group;138
12.2;2 The Potexvirus Group;142
12.3;3 The Tobamovirus Group;143
12.4;4 The Tymovirus Group;156
12.5;5 The Comovirus Group;160
12.6;6 The Bromovirus Group;164
12.7;7 The Tobravirus Group;167
12.8;Further Reading;170
13;CHAPTER 8. Replication of Other Virus Groups and Families;171
13.1;1 Caulimovirus Group;172
13.2;2 Geminivirus Group;180
13.3;3 Plant Reoviridae;184
13.4;4 Plant Rhabdoviridae;187
13.5;5 Plant Bunyaviridae;190
13.6;6 Possible Uses of Viruses for Gene Transfer;192
13.7;Further Reading;194
14;CHAPTER 9. Small Nucleic Acid Molecules That Cause or Modify Diseases;196
14.1;1 Viroids;197
14.2;2 Satellite Viruses and Satellite RNAs;208
14.3;3 Defective Interfering Particles;216
14.4;Further Reading;217
15;CHAPTER 10. Transmission, Movement, and Host Range;218
15.1;1 Direct Passage in Living Higher Plant Material;219
15.2;2 Transmission by Organisms Other than Higher Plants;222
15.3;3 Mechanical Transmission;223
15.4;4 Movement and Final Distribution in the Plant;227
15.5;5 The Molecular Basis for Host Range;231
15.6;6 Discussion and Summary;234
15.7;Further Reading;236
16;CHAPTER 11. Host Plant Responses to Virus Infection;237
16.1;1 The Kinds of Host Response to Inoculation with a Virus;238
16.2;2 The Responses of Susceptible Hosts;238
16.3;3 The Responses of Resistant Hosts;252
16.4;4 The Role of Viral Genes in the Induction of Systemic Disease;258
16.5;5 Processes Involved in Disease Induction;261
16.6;6 Factors Influencing the Course of Infection and Disease;265
16.7;7 Discussion and Summary;272
16.8;Further Reading;273
17;CHAPTER 12. Variability;275
17.1;1 Isolation of Strains;276
17.2;2 The Molecular Basis for Variation;278
17.3;3 Criteria for the Recognition of Strains;281
17.4;4 Virus Strains in the Plant;293
17.5;5 Discussion and Summary;297
17.6;Further Reading;301
18;CHAPTER 13. Relationships between Plant Viruses and Invertebrates;302
18.1;1 Vector Groups;303
18.2;2 Nematodes (Nematoda);303
18.3;3 Aphids (Aphididae);305
18.4;4 Leafhoppers and Planthoppers (Auchenorrhyncha);312
18.5;5 Insects with Biting Mouthparts;316
18.6;6 Other Vector Groups;317
18.7;7 Pollinating Insects;320
18.8;Further Reading;320
19;CHAPTER 14. Ecology;321
19.1;1 Biological Factors;322
19.2;2 Physical Factors;333
19.3;3 Survival through the Seasonal Cycle;336
19.4;4 Conclusion;337
19.5;Further Reading;337
20;CHAPTER 15. Economic Importance and Control;338
20.1;1 Economic Importance;338
20.2;2 Diagnosis;341
20.3;3 Control Measures;342
20.4;Further Reading;361
21;CHAPTER 16. Nomenclature, Classification, Origins, and Evolution;362
21.1;1 Nomenclature;364
21.2;2 Classification;364
21.3;3 Speculation on Origins;370
21.4;4 Evolution;374
21.5;5 Genome and Amino Acid Sequence Similarities between Viruses Infecting Plants and Animals;381
21.6;Further Reading;387
22;CHAPTER 17. Future Prospects for Plant Virology;388
22.1;1 A Brief Look at the Past;388
22.2;2 Toward the Twenty-First Century;390
23;Appendix;394
24;Bibliography;400
25;Index;408

Leseproben

2

Principal Techniques for the Study of Virus Particle and Genome Structure

1 Structure of Virus Particles

1.1 X-ray Crystallographic Analysis

1.2 Electron Microscopy

2 The Structure of Viral Genomes

2.1 Classical Procedures

2.2 Gene-Manipulation Technology

3 Amino Acid Sequences of Viral Proteins

4 mRNAs

4.1 Isolation

4.2 In Vitro Translation

4.3 Hybrid Arrest and Hybrid Selection Procedures

5 Introduction of a DNA Step into the Life Cycle of RNA Plant Viruses

5.1 RNA Genomes with Uniform Sequences

5.2 Reverse Genetics

5.3 Recombinant Viruses

6 Transgenic Plants

6.1 The Agrobacterium tumefaciens Vector System

6.2 Direct Gene Transfer to Plant Cells

7 The Polymerase Chain Reaction

Further Reading

The study of a plant virus usually begins with investigation of two aspects, the structure of the virus particle and the organization of the viral genome. The most important methods used in such studies are outlined briefly in this chapter.

1 STRUCTURE OF VIRUS PARTICLES

The two major techniques for studying virus structure are X-ray crystallography and electron microscopy using various kinds of specimen preparation.

1.1 X-RAY CRYSTALLOGRAPHIC ANALYSIS

When X-rays pass through a crystal, the rays are scattered in a regular manner. The scattered radiation can be recorded photographically. What is recorded is, however, not a picture of the virus particle, but a very abstract-appearing collection of dots from which the structure of the virus particle is deduced by complex mathematical analysis. Inducing virus particles to form crystals suitable for X-ray crystallography is more of an art than a science, and generally requires many trials of salt and alcohol solutions and other precipitating conditions to obtain crystals of sufficient size and stability. Isometric particles will form true crystals. Rod-shaped, rigid virus particles often will form liquid crystals in which the rods are regularly arrayed in two dimensions. X-ray analysis can be applied to such crystals, but not to rod-shaped viruses with flexuous particles or to large virus particles with lipoprotein envelopes.

Where they can be applied, X-ray techniques provide the most powerful means of obtaining information about virus structure. Over the past 10 years, significant advances have allowed the application of X-ray crystallographic analysis to more viruses and at higher resolutions. With the definition of structures at atomic level, it has been possible to define interactions between the viral genome and the protecting protein coat, and to establish the positions of water molecules and divalent cations in the structure.

In summary, the major technical advances responsible for this progress have been (1) high-intensity, coherent X-ray sources that allow data to be recovered in a short time from delicate crystals; (2) an increase in the speed and capacity of computers, together with a reduced cost of computing; (3) noncrystallographic symmetry averaging, a process involving successive approximations that remove noise and enhance detail in the density map; and (4) the development of computer graphics, replacing the laborious manual model building that was required previously to refine structures.

There is a significant limitation for the study of small isometric viruses that can be crystallized. Such viruses crystallize because of regular symmetries in the protein shell. However, most of the nucleic acid inside the virus is not arranged in a regular manner with respect to these symmetries. Thus, very little information can usually be obtained about the conformation of the genome within the virus. Such information can be obtained for the rigid rod-shaped viruses, in which the RNA is arranged in a regular helix within a cylinder of protein.

1.2 ELECTRON MICROSCOPY

Development of images using electron microscopy depends on differences in electron scattering in different parts of the specimen. Virus particles themselves have very little contrast with respect to the scattering of electrons, compared with the carbon film on which they are usually mounted. For this reason, various specimen-preparation techniques have been used to enhance contrast. In early work, shadowing of the specimen at an angle with a vaporized heavy metal, such as gold, was employed. This procedure, however, obscured much detail. It was subsequently shown that various osmium, lead and uranyl compounds, and phosphotungstic acid (under certain conditions) react chemically with, and are bound to the virus. This procedure was called positive staining, but it was found to cause alteration in or disintegration of the virus structure. Today negative staining is the most widely used procedure for visualization of viruses in the electron microscope.

1.2.1 Negative Staining

Negative staining uses potassium phosphotungstate at pH 7.0, or uranyl acetate or formate near pH 5.0. The electron-dense material does not react chemically with the virus, but penetrates available spaces on the surface and within the virus particle. The virus structure stands out against the electron-dense background (Fig. 5.2). However, even in the best electron micrographs, fine details of structure tend to be obscured, first, by noise due to minor irregularities in the virus particle image and in the stain, and second, by the fact that contrast due to the stain is often developed on both sides of the virus particle to a varying extent. Thus electron micrographs of very high quality are essential in order to distinguish particles of small isometric viruses belonging to different virus groups. More detailed structural information may be obtained from a number of images of single negatively stained particles, by processing the image in one of several ways (e.g., Fig. 5.9).

1.2.2 Thin Sections

The diameter of small isometric viruses (20–30 nm) is much less than the thickness of a typical thin section (˜ 40–100 nm) used to study tissues by electron microscopy. Thus, no detailed structural information is revealed. However, some aspects of the structure of the larger viruses with lipoprotein envelopes can be studied using thin sections of infected cells (Fig. 5.16) or of a pellet containing the virus.

1.2.3 Cryoelectron Microscopy

Cryoelectron microscopy is a recently developed technique. The specimen is frozen extremely rapidly in an aqueous medium. The virus is suspended in a very thin film of liquid stretching across holes in a carbon grid, which is plunged into liquid ethane that contains some ethane ice (183 °C). The freezing is so rapid that water molecules do not have time to form micro ice crystals; thus, the specimen is frozen in vitreous ice with no damage caused by crystallization of water. The method is being usefully applied to the study of virus structures or substructures that may be altered by other specimen-preparation techniques.

2 THE STRUCTURE OF VIRAL GENOMES

2.1 CLASSICAL PROCEDURES

The nature of a viral nucleic acid, whether it is DNA or RNA, and whether it is single-stranded or double-stranded, circular or linear, can be established by various standard physical, chemical and enzymatic methods. Chemical and enzymatic procedures allow known special structures at the 5'- or 3'-end of linear genomic nucleic acid to be identified. Electrophoresis of purified nucleic acid from virus particles usually will give good estimates of the RNA or DNA molecular weight and the number of different size classes of genomic nucleic acid for those viruses with split genomes. The application of gene-manipulating technology is also rapidly increasing our understanding of the structure of viral genomes and how they replicate.

2.2 GENE-MANIPULATION TECHNOLOGY

2.2.1 Importance

There are two situations in which viral genome sequence information is of great use. Each of these situations has theoretical and practical aspects.

The Virus in the Plant

Theoretical A knowledge of the viral genes and the products they code for is beginning to lead to an understanding of how viruses cause disease.

Practical The ability to identify and isolate particular viral genes and integrate them into the host-plant genome is providing novel methods for understanding virus gene function and, in some instances, for the control of virus diseases.

The Virus in Relation to Other Viruses

Theoretical A knowledge of the nucleotide sequences of many viral genomes is of very great assistance in virus classification. The nucleotide sequences are revealing unexpected relationships between viruses, and this information is beginning to give us an understanding of how viruses might have originated and how they evolved. Computer- aided comparison of a viral nucleotide sequence with those of other viruses, and sequences encoding cellular proteins can sometimes indicate possible viral protein functions.

Practical It is essential to be...