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THE VIRUSES
Series Editors HEINZ FRAENKEL-CONRAT, University of California
Berkeley, California
ROBERT R. WAGNER, University of Virginia School of Medicine Charlottesville, Virginia
THE VIRUSES: Catalogue, Characterization, and Classification Heinz Fraenkel-Conrat
THE ADENOVIRUSES Edited by Harold S. Ginsberg
THE HERPESVIRUSES, Volumes 1-3 • Edited by Bernard Roizman Volume 4 • Edited by Bernard Roizman and Carlos Lopez
THE PAPOVAVIRIDAE Volume 1 • Edited by Norman P. Salzman
THE PARVOVIRUSES Edited by Kenneth I. Berns
THE PLANT VIRUSES Volume 1 • Edited by R. I. B. Francki Volume 2. Edited by M. H. V. Van Regenmortel and Heinz Fraenkel-Conrat
THE REOVIRIDAE Edited by Wolfgang K. Joklik
THE TOGAVIRIDAE AND FLA VIVIRIDAE Edited by Sondra Schlesinger and Milton J. Schlesinger
The Plant Viruses Volume 2 THE ROD-SHAPED PLANT VIRUSES
Edited by
M. H. V. VAN REGENMORTEL Institute of Molecular and Cellular Biology Strasbourg, France
and
HEINZ FRAENKEL-CONRA T Department of Moleculo.r Biology and Virus Laboratory University of California Berkeley, California
PLENUM PRESS • NEW YORK AND LONDON
Library of Congress Cataloging in Publication Data
The Plant viruses.
(Viruses) Contents: v. 2. The rod-shaped plant viruses/edited by M. H. V. Van Regenmortel
and Heinz Fraenkel-Conrat. Bibliography: v. 2, p. Includes index. 1. Plant viruses. 2. Tobacco mosaic virus. I. Van Regenmortel, M. H. V. II.
Fraenkel-Conrat, Heinz, 1910- III. Series. QR402.P57 1986 576'.6483 86-9517
ISBN 978-1-4684-7028-4 ISBN 978-1-4684-7026-0 (eBook) DOI 10.1007/978-1-4684-7026-0
© 1986 Plenum Press, New York Softcover reprint of the hardcover 1st edition 1986 A Division of Plenum Publishing Corporation 233 Spring Street, New York, N.Y. 10013
All rights reserved
No part of this book may be reproduced, stored in a retrieval system, or transmitted in any form or by any means, electronic, mechanical, photocopying, microfilming, recording, or otherwise, without written permission from the Publisher
Contributors
J. G. Atabekov, Department of Virology, Moscow State University, Moscow 119899, USSR
A. C. Bloomer, MRC Laboratory of Molecular Biology, Cambridge CB2 2QH, England
Alan A. Brunt, Glasshouse Crops Research Institute, Littlehampton, West Sussex BN17 6LP, England
P. J. G. Butler, MRC Laboratory of Molecular Biology, Cambridge CB2 2QH, England
T. W. Carroll, Department of Plant Pathology, Montana State University, Bozeman, Montana 59717
R. G. Christie, Plant Virus Laboratory, Agronomy Department, University of Florida, Gainesville, Florida 32611
V. V. Dolja, Department of Virology, Moscow State University, Moscow 119899, USSR
J. R. Edwardson, Plant Virus Laboratory, Agronomy Department, University of Florida, Gainesville, Florida 32611
H. Fraenkel-Conrat, Virus Laboratory and Depaitment of Molecular Biology, University of California, Berkeley, California 94720
Adrian Gibbs, Research School of Biological Sciences, Australian National University, Canberra, Australian Capital Territory, 2601, Australia
G. V. Gooding, Jr., Department of Plant Pathology, North Carolina State University, Raleigh, North Carolina 27695
B. D. Harrison, Scottish Crop Research Institute, Invergowrie, Dundee DD2 5DA, Scotland
Yoshimi Okada, Department of Biophysics and Biochemistry, Faculty of Science, University of Tokyo, Hongo Bunkyo-ku, Tokyo, 113, Japan
Peter Palukaitis, Department of Plant Pathology, Cornell University, Ithaca, New York 14853
D. J. Robinson, Scottish Crop Research Institute, Invergowrie, Dundee DD2 5DA, Scotland
v
vi CONTRIBUTORS
Satyabrata Sarkar, Institute of Plant Medicine, University of Hohenheim, 7000 Stuttgart 70, West Germany
Eishiro Shikata, Department of Botany, Faculty of Agriculture, Hokkaido University, Sapporo, Japan
M. H. V. Van Regenmortel, Institut de Biologie Moleculaire et Cellulaire du CNRS, 67084 Strasbourg Cedex, France
Anupam Varma, Division of Mycology and Plant Pathology, Indian Agricultural Research Institute, New Delhi 110012, India
Carl Wetter, Department of Botany, University of Saarland, D-6600 Saarbriicken, West Germany
Milton Zaitlin, Department of Plant Pathology, Cornell University, Ithaca, New York 14853
F. W. Zettler, Plant Pathology Department, University of Florida, Gainesville, Florida 32611
Preface
This volume of the series The Plant Viruses is devoted to viruses with rod-shaped particles belonging to the following four groups: the tobamoviruses (named after tobacco mosaic virus), the tobraviruses (after tobacco rattle), the hordeiviruses (after the latin hordeum in honor of the type member barley stripe mosaic virus), and the not yet officially recognized furoviruses (fungus-transmitted rod-shaped viruses, Shirako and Brakke, 1984).
At present these clusters of plant viruses are called groups instead of genera or families as is customary in other areas of virology. This peculiarity of plant viral taxonomy (Matthews, 1982) is due to the fact that the current Plant Virus Subcommittee of the International Committee of Taxonomy of Viruses is deeply split on what to call the categories or ranks used in virus classification.
Some plant virologists believe that the species concept cannot be applied to viruses because this concept, according to them, necessarily involves sexual reproduction and genetic isolation (Milne, 1984; Murant, 1985). This belief no doubt stems from the fact that these authors restrict the use of the term species to biological species. According to them, a collection of similar viral isolates and strains does constitute an individual virus, i.e., it is a taxonomy entity separate from other individual viruses. However, instead of calling these elementary units of classification: different virus species, these authors call them viruses, refusing to acknowledge the fact that there is a need for a word to signify that one is not referring to a viral object but to a taxonomic construct (an abstract concept as opposed to a collection of material objects).
Some of the protagonists of this viewpoint (Milne, 1984) go as far as to deny that there is a difference between the existence of a concept and the existence of material objects, and they reject the view that classifications are conceptual constructions. It is not clear why the word species should be used only in the sense of biological species defined by gene pools and breeding barriers, and why a phenetic or morphological
vii
viii PREFACE
definition of species, as practiced by numerical taxonomists, should not prove acceptable for classifying viruses.
The material objects, i.e., the viruses discussed in the present volume, have been grouped according to the divisions embodied in the CMII AAB descriptions of plant viruses. In the past, most tobamoviruses such as ribgrass mosaic virus or cucumber virus 4 were considered strains of tobacco mosaic virus (TMV).
As new CMII AAB descriptions of tobamoviruses are published and the corresponding taxonomic entity is given a name, it has become standard practice to consider that these names now stand for individual viruses and not for individual strains of TMV. According to standard taxonomic parlance, these individual viruses have thus become de facto species (Matthews, 1985). In addition to the species TMV, six other spe.;ies of tobamoviruses are discussed at length in the present volume (Chapters 9-14). Following standard taxonomic categories and terminology, the tobamovirus group can be considered a genus made up of a serologically homogeneous cluster of related species. Similarly the furo-, tobra-, and hordeivirus groups can be taken to represent three separate plant virus genera.
About a third of this volume is devoted to TMV, a deliberate choice in view of the importance of this virus for the development of virology. Although the common TMV strain is perhaps the best studied object in the whole of virology, the reader will discover that the boundaries of our knowledge concerning this virus are still being extended and that the end is not yet in sight. The open-ended nature of scientific knowledge is never more apparent than in the description of a subject that has been very extensively researched.
Strasbourg Berkeley
REFERENCES
M. H. V. Van Regenmortel H. Fraenkel-Conrat
Milne, R. G., 1984, The species problem in plant virology, Microbio1. Sci. 1:113-117. Matthews, R. E. F., 1982, Classification and nomenclature of viruses, fourth report of the
international committee on taxonomy of viruses, Intervirology 17:1-199. Matthews, R. E. F., 1985, Viral taxonomy, Microbio1. Sci. 2:74-76. Murant, A. F., 1985, Taxonomy and nomenclature of viruses, Microbio1. Sci. 2:218-220. Shirako, Y., and Brakke, M. K., 1984, Two purified RNAs of soil-borne wheat mosaic virus
are needed for infection, f. Gen. Viro1. 65:119-127.
Contents
I. Tobamoviruses
Chapter 1
Tobacco Mosaic Virus: The History of Tobacco Mosaic Virus and the Evolution of Molecular Biology ............................................... 5
H. Fraenkel-Conrat
Chapter 2
Tobacco Mosaic Virus: Structure and Self-Assembly
A. C. Bloomer and P. r. G. Butler
I. Introduction .......................................................................... 19 II. Structure ............................................................................... 20
A. Polymorphic Aggregates of Protein .................................. 21 B. Detailed Molecular Structures ......................................... 25
III. Self-Assembly ........................................................................ 34 A. Nucleation ....................................................................... 34 B. Elongation ....................................................................... 40
IV. Conclusions .......................................................................... 51 References ...................................................................................... 52
Chapter 3
Tobacco Mosaic Virus: Mutants and Strains
Satyabrata Sarkar
I. Introduction .......................................................................... 59 II. Isolation of Variants .............................................................. 60
ix
x CONTENTS
A. Source and Properties of a Few Strains and Mutants of TMV ............................................................................ 60
B. Induced Mutants .............................................................. 63 C. Apparently Induced but Possibly Spontaneous
Mutants ........................................................................... 68 III. Contribution of Mutants and Strains of TMV to Virology
and Molecular Biology ........................................................... 69 References ...................................................................................... 72
Chapter 4
Tobacco Mosaic Virus: Antigenic Structure
M. H. V. Van Regenmortel
I. Introduction .......................................................................... 79 II. Methods Used to Study TMV Antigenicity......... .................. 80
A. Fragmentation of the Protein ........................................... 81 B. Studies with Synthetic Peptides ...................................... 82 C. Cross-Reactivity Studies with Antipeptide Antibodies .... 83 D. Cross-Reactivity Studies with TMV Mutants .................. 84 E. Studies with Monoclonal Antibodies ............................... 85
III. Types of Epitopes Identified in TMV and TMVP ........ ..... ...... 86 A. Continuous Epitopes ....................................................... 86 B. Discontinous Epitopes ..................................................... 90 C. Neotopes ......................................................................... 93 D. Cryptotopes ..................................................................... 94
IV. Determination of the Binding Constant of TMV Antibodies ................................................................ 96
V. Applications of Serology in TMV Studies ........ ...................... 98 A. Virus Detection ............................................................... 98 B. Virus Classification ......................................................... 99
References ...................................................................................... 100
Chapter 5
Tobacco Mosaic Virus: Infectivity and Replication
Peter Palukaitis and Milton Zaitlin
I. Introduction .......................................................................... 105 II. Infection and Pathogenicity ................................................... 106
A. Viral Ingress into the Plant .............................................. 106 B. Site of Viral Entry into the Plant and the Cell ................ 107 C. Virus Movement from Cell to Cell .................................. 108 D. Long-Distance Virus Movement ...................................... 109 E. Symptom Determinants .............. ........ .... ...... .................. 110
III. Replication ............................................................................ 111 A. Introduction ..................................................................... III
CONTENTS xi
B. Gene Organization ........................................................... III C. TMV Life Cycle .................... .................................... ....... 119 D. Cross-Protection versus Replication ................................ 124
References ...................................................................................... 126
Chapter 6
Tobacco Mosaic Virus: Epidemiology and Control
G. V. Gooding, Tr.
I. Introduction .......................................................................... 133 II. The Disease ........................................................................... 133
A. Etiology ........................................................................... 133 B. Symptoms ............................... ......................................... 135 C. Identification ........................... ........................................ 135 D. Effects on the Host .......................................................... 135 E. Economic Importance ...................................................... 137
III. Epidemiology ......................................................................... 137 A. Sources of Inoculum ........................................................ 137 B. Transmission ............................ ....................................... 139 C. Environmental Factors ..................................................... 140
IV. Control .................................................................................. 141 A. Resistance ........................................................................ 141 B. Tolerance ......................................................................... 142 C. Prevention of Primary Infection ...................................... 143 D. Prevention of Secondary Spread ....................................... 145 E. Chemical ......................................................................... 146 F. Cross-Protection and Interference .................................... 147
V. Discussion ........ .......... ........................................................... 147 References ...................................................................................... 148
Chapter 7
Tobacco Mosaic Virus: Cytopathological Effects
T. R. Edwardson and R. G. Christie
I. Introduction .......................................................................... 153 II. Crystalline Inclusions ........................................................... 154
III. Paracrystals .................. .................... .......................... ........... 156 IV. Angled-Layer Aggregates ....................................................... 157 V. X-Bodies ................................................................................ 157
VI. Virus Aggregates in Chloroplasts .......................................... 158 VII. Other Types of Cytoplasmic Inclusions ................................ 159
VIII. Nuclear Inclusions ................................................................ 161 IX. Concluding Remarks ............................................................. 162
References ...................................................................................... 163
xii CONTENTS
Chapter 8
Tobamovirus Classification
Adrian Gibbs
I. Relationship among the Definitive Tobamoviruses ............... 168 A. Coat Protein .................................................................... 168 B. 1/30K" Protein .................................................................. 174 C. 3' Noncoding Region of the Genome ............................... 174 D. The Genome .................................................................... 174 E. Host Range ...................................................................... 176
II. Relationships between Tobamoviruses and Other Viruses .... 177 III. Conclusions .......................................................................... 178
References ...................................................................................... 178
Chapter 9
Tomato Mosaic Virus
Alan A. Brunt
I. Introduction .......................................................................... 181 II. The Virus and Its Strains ....................................................... 181
A. Symptomatologically Distinct Strains ............................. 183 B. Strains (or Pathotypes) Differentiated by Host
Resistance Genes ............................................................. 186 III. Properties and Composition .................................................. 186
A. Properties ........................................................................ 186 B. Composition .................................................................... 187
IV. Affinities ............................................................................... 192 A. Serological Relationships ..................... .... ........................ 192 B. Molecular Hybridization Analyses ................................... 193 C. Amino Acid Analyses ...................................................... 194
V. Intracellular Occurrence ........................................................ 194 VI. Epidemiology and Control ..................................................... 195
A. Epidemiology ................................................................... 195 B. Control ............................................................................ 195
References ...................................................................................... 197
Chapter 10
Tobacco Mild Green Mosaic Virus
Carl Wetter
I. Introduction .......................................................................... 205 II. Biological Properties .............................................................. 206
A. Virus Strains and Their Economic Importance ................ 206
CONTENTS xiii
B. Host Range and Symptomatology .................................... 206 C. Cytopathological Effects .................................................. 207
m. Physicochemical Properties ................................................... 210 A. Purification ...................................................................... 210 B. Particle Morphology ........................................................ 210 C. Virion Properties .............................................................. 211 D. Nucleotide Sequence Homology ...................................... 211 E. Protein Composition ....................................................... 211
IV. Serology ................................................................................. 212 V. Interaction of TMGMV with Other Tobamoviruses .............. 213
A. Cross-Protection and Interference .................................... 213 B. Interference at an Early Stage of Infection ....................... 215 C. Structural Interactions of Particles .................................. 216
VI. Virus Mutation versus Host-Induced Mutation ..................... 216 References ...................................................................................... 217
Chapter 11
Ribgrass Mosaic Virus
Carl Wetter
I. Introduction .......................................................................... 221 II. Biological Properties .............................................................. 221
A. Isolates and Strains of RMV and Their Economic Importance ...................................................... 221
B. Symptomatology and Host Range ........ .................. .......... 222 C. Cytopathology ................................................................. 224
III. Physicochemical Properties ................................................... 225 A. Purification ...................................................................... 225 B. Particle Morphology ........................................................ 225 C. Virion Properties .............................................................. 227 D. The Coat Protein ............................................................. 227 E. Structural Interactions ..................................................... 228
IV. Serology ................................................................................. 228 References ...................................................................................... 230
Chapter 12
Odontoglossum Ringspot Virus
r R. Edwardson and F. W. Zettler
I. Historical Review .................................................................. 233 II. Structure ........ ............................ .......... ...................... ........... 233
III. ORSV Mutants or Strains ..................................... ....... .......... 235 IV. Antigenic Structure ............................................................... 236 V. Pathogenicity ........................................................................ 236
xiv CONTENTS
VI. Transmission, Epidemiology, Control .............. ..................... 238 VII. Cytopathology ....................................................................... 241
References ...................................................................................... 243
Chapter 13
Sunn-Hemp Mosaic Virus
Anupam Varma
I. Introduction .......................................................................... 249 II. Important Diseases and Their Geographical Distribution ..... 249
III. Host Range and SYlllptoms ................................................... 250 A. Diagnostic Species ........................................................... 250 B. Inclusion Bodies .............................................................. 251 C. Physiological Changes ..................................................... 251 D. Interaction with Viruses and Fungi ................................. 252
IV. Strains ................................................................................... 252 A. Probable Strains ............................................................... 252 B. Thermophilic Strain ........................................................ 253 C. Host-Induced Changes ..................................................... 253
V. Transmission ......................................................................... 254 A. Vector Transmission ........................................................ 255 B. Seed Transmission ........................................................... 255
VI. Stability in Sap .... .................. ................ .......................... ...... 256 VII. Serological Relationships ....................................................... 256
VIII. Properties of Particles ............................................................ 257 A. Structure and Sedimentation ........................................... 257 B. Ultraviolet Absorption ..................................................... 257
IX. Particle Composition ............................................................. 257 A. Protein '" .................... .... .. ...... ................ .......... .... .. .. ........ 257 B. Nucleic Acid .................................................................... 260
X. Biological Significance of the Two Types of Particles ........... 261 A. Relative Production of Short and Full-Length Particles
in Plants .......................................................................... 261 B. Separation of Short and Full-Length Particles .................. 261 C. Infectivity ........................................................................ 261 D. Translation of RNAs from Short and Full-Length
Particles in Cell-Free Systems ......................................... 261 E. Polyribosome-Associated Coat Protein mRNA
in Plants .......................................................................... 262 XI. Ecology and Control.......... .................................................... 263
XII. General Remarks ................................................................... 264 References .... .................................................................................. 264
CONTENTS
Chapter 14
Cucumber Green Mottle Mosaic Virus
Yoshimi Okada
xv
I. Introduction .......................................................................... 267 II. Strains ................................................................................... 268
A. Type Strain (Cucumber Virus 3) ...................................... 268 B. Cucumber Aucuba Mosaic Strain (Cucumber Virus 4) .... 268 C. Watermelon Strain ........................................................... 268 D. Japanese Cucumber Strain ............................................... 269
III. Virus Particle ........................................................................ 269 IV. Genomic and Subgenomic RNA ............................................ 269
A. Nucleotide Composition and Sequence of Genomic RNA ................................................................. 269
B. Coat Protein and 30K Protein Cistron ............................. 270 C. Nucleotide Sequence of the Assembly Origin and
Comparison with That of TMV ....................................... 271 D. The 3' Noncoding Region ................................................ 272 E. Subgenomic RNA ............................................................ 273
V. Coat Protein .......................................................................... 273 A. Amino Acid Sequence ..................................................... 273 B. Anomalous Mobility of the CGMMV Coat Protein on
SDS-Polyacrylamide Gel Electrophoresis ........................ 274 C. Aggregation State of the Coat Protein ............................. 274 D. RNA Location in the CGMMV Protein Disk .................. 275
VI. Virus Particle Assembly in Vitro ........................................... 277 A. Specificity of the Assembly Reaction in Vitro ................. 277 B. Studies on TMV Assembly Using the
CGMMV Protein ............................................. ,............... 277 References ...................................................................................... 278
Chapter 15
Miscellaneous Tobamoviruses
Alan A. Brunt
I. Introduction .......................................................................... 283 II. The Viruses and Their Natural Occurrence .......................... 283
A. The Viruses and Their Hosts ........................................... 283 B. Intracellular Occurence of the Viruses ............................ 292
III. Properties .............................................................................. 292 A. General Properties of Particles ........................................ 292 B. Composition .................................................................... 294
IV. Serological Affinities ............................................................. 296 References ............... .. .... ................................................................. 300
xvi CONTENTS
II. Fungus-Transmitted and Similar Labile Rod-Shaped Viruses
Chapter 16
Fungus-Transmitted and Similar Labile Rod-Shaped Viruses
Alan A. Brunt and Eishiro Shikata
I. Introduction .......................................................................... 305 II. The Viruses and Their Natural Hosts ................................... 309
A. The Viruses and the Diseases They Cause ...................... 309 B. Intracellular Occurrence and Cytopathology ................... 312
III. Transmission and Disease Control ........................................ 312 A. Fungal Vectors and Virus-Vector Relationships .............. 312 B. Seed Transmission .................................................. ......... 313
IV. Virus Purification .................................................................. 314 V. Properties of Virus Particles .................................................. 315
A. Morphology, Size, Structure, and Infectivity .................... 315 B. General Properties ........................................................... 322 C. Composition .................................................................... 324 D. Serological Affinities ....................................................... 327
VI. Taxonomy ............................................................................. 329 References ...................................................................................... 330
Chapter 17
Tobraviruses
III. Tobraviruses
B. D. Harrison and D. J. Robinson
I. Recognition and Characteristics of the Tobravirus Group ..... 339 A. Members and Their Geographical Distribution ............... 339 B. General Properties of Tobraviruses .................................. 339
II. Tobravirus Particles and Their Components ......................... 341 A. Particle Morphology and Structure .................................. 341 B. Particle Protein Size and Structure .................................. 343 C. The RNA Species and Their Structure ............................ 343 D. Particle Protein Aggregation and
Nucleoprotein Reassembly .............................................. 344 III. Variation and Relationships .................................................. 345
A. Biological Variation ......................................................... 345 B. Antigenic Variation ......................................................... 346 C. Cross-Protection between Isolates ........................ ........... 346 D. Pseudorecombinant Formation ........................................ 346
CONTENTS xvii
E. RNA Sequence Homologies ............................................. 347 F. Pseudorecombination in Nature ...................................... 348 G. Classification of Tobraviruses .......................................... 348
IV. Replication and Genome Strategy . ............ .................. ..... ..... 349 A. Multiplication in Plants .................................................. 349 B. Replication in Protoplasts ............ .... ................................ 349 C. Interactions with Cells .................. ........ .......................... 350 D. Strategy of Genome Expression ....................................... 351 E. Distribution of Genetic Determinants ... .......................... 352
V. Natural History ..................................................................... 353 A. Diseases Caused .............................................................. 353 B. Nematode Transmission .................................................. 356 C. Seed Transmission ........................................................... 356 D. Ecology ............................................................................ 358 E. Control ............................................................................ 359
VI. Detection and Identification .................................................. 360 VII. Affinities with Other Virus Groups ....................................... 361
VIII. Special Features ..................................................................... 363 References ...................................................................................... 364
IV. Hordeiviruses
Chapter 18
Hordeiviruses: Biology and Pathology
T. W. Carroll
I. Introduction .......................................................................... 373 II. Barley Stripe Mosaic Virus ............................ ........................ 373
A. Main Characteristics ............................... ........................ 373 B. Geographical Distribution ............................................... 374 C. Host Range and Symptomatology .................................... 375 D. Strains ............................................................................. 376 E. Cytological Effects on Host ............................................ 378 F. Physiological Effects on Host .......................................... 378 G. Transmission through Pollen and Seed ............................ 380 H. Methods of Disease Diagnosis and Virus Detection ........ 382 I. Economic Significance ..................................................... 384 J. Epidemiology................................................................... 385 K. Control ............................................................................ 386
III. Poa Semilatent Virus .................. .............. .................... ......... 388 IV. Lychnis Ringspot Virus ... ............ ...... ..... ... .... ............ ...... ...... 390 V. Closing Remarks ................................................................... 391
References ...................................................................................... 392
xviii CONTENTS
Chapter 19
Hordeiviruses: Structure and Replication
J. G. Atabekov and V. V. Dolia
I. Introduction .......................................................................... 397 II. General Biological Characteristics ......................................... 398
III. The Virions and Their Substructural Components ................ 399 A. Purified BSMV ................................................................. 399 B. Coat Protein .................................................................... 400 C. Polymerization of the Capsid Protein and
Virion Reassembly ........................................................... 401 IV. Genome Structure and Expression ........................................ 404
A. Multipartite Nature of the Genome ................................ 404 B. Sequence Relationship among BSMV RNAs .................... 406 C. Changes in the Set of Virion RNAs upon Laboratory
Passaging of BSMV .......................................................... 406 D. Structure of the 3'-Terminal Region of BSMV RNAs ...... 407 E. Translation in Vitro of Individual BSMV RNAs .............. 409 F. Subgenomic RNAs of BSMV ............................................ 413 G. Replication of BSMV ....................................................... 414 H. BSMV-Induced Mutagenesis in Host Plants ..................... 414
V. Concluding Remarks ............................................................. 415 References ...................................................................................... 417
Index .............................................................................................. 421