Seed-Borne Plant Virus Diseases

Seed-borne Plant Virus Diseases

K. Subramanya Sastry

Seed-borne Plant Virus Diseases

123 K. Subramanya Sastry Emeritus Professor Department of Virology S.V. University Tirupathi, AP India

ISBN 978-81-322-0812-9 ISBN 978-81-322-0813-6 (eBook) DOI 10.1007/978-81-322-0813-6 Springer New Delhi Heidelberg New York Dordrecht London

Library of Congress Control Number: 2012945630

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Springer is part of Springer Science+Business Media (www.springer.com) About the Author

Prof. K. Subramanya Sastry, Ph.D., is emeritus professor in the department of virology at S.V. University, Tirupathi Ð 517502, A.P., India. (India). He obtained his M.Sc. (Botany) and Ph.D. (Botany) with plant virology special- ization in 1966 and 1973, respectively, from Sri Venkateswara University, Tirupati (India). He joined Indian Council of Agricultural Research (ICAR) as a scientist (Plant Virology) during the year 1971 and retired in 1999. He has served at Indian Institute of Horticultural Research, Hessaraghatta, Bangalore 560 089, Karnataka, and also at Directorate of Oil Seeds Research, Hyderabad 500 080, Andhra Pradesh. Prof. Sastry’s research has been primarily on epidemiology and management of virus and virus-like diseases of Horticultural and Oil Seed crops. He has done pioneer research on Begomoviruses of tomato and okra. He has research experience in molecular and biotechnological approaches for characterization and control of viral diseases of horticultural crop plants. Further, he has also published over 120 research papers both in national and international journals. He has also published “Compendium of the Plant Virus Research in India (1903–2008)” having 8,652 plant virus references that is considered as one of the rich sources of information for Indian plant virus research.

Foreword

I am delighted to write the foreword for a book on seed-borne viruses, since many economically important viral diseases are spread in nature through seeds. Increasing our knowledge on all aspects of seed-borne viruses is the ﬁrst step towards developing a strategy for their control. This book represents a comprehensive up-to-date treatise for seed-borne viruses, including detection methods, ecology, epidemiology and control. Attention is also placed on the importance of integrated management to reduce losses caused by seed- borne viruses. I congratulate Dr. K. S. Sastry for his sincere effort and many years of hard work to assemble existing information on seed-borne viruses and make them available in a well organized manner to a wide audience: research scientists, graduate students, extension workers, progressive farmers as well as individuals who are interested in agricultural production at large. I am conﬁdent that this book will serve as an important reference for seed-borne viruses which affect agricultural crops, globally. Legume crops are the main source of protein for the majority of people in developing countries. Around 50% of the viruses which infect legumes are seed-borne, and some of them could lead to a complete crop failure. Improving our knowledge on these viruses can be well translated to improved legume crops production, worldwide. It is hoped that this book will serve as an important resource for all agricultural workers dedicated to improved and stabilized crop production through adoption of environment-friendly practices, including the use of virus-free seeds.

Khaled M. Makkouk Advisor for Agriculture and Environment National Council for scientiﬁc Research (CNRS) P.O. Box 11-8281 Riad El-Solh 1107 2260, Beirut, LEBANONCNRS, Beirut, Lebanon

vii

Preface

Seed, a highly ordered plant structure, is the basic input in crop production. It possesses the qualities necessary for cell division, morphogenesis and regeneration of species. The study of seed itself is as good as the study of life. Seed is one of the vital inputs in the development of agriculture in any country. To increase agricultural production, viability of quality seed is one of the prerequisites. The seed is also one of the most important source for the perpetuation of fungi, bacteria, nematodes, insects, viruses, etc. and acts as an efficient carrier for their spread to new areas through introduction and/or seed trade which is a global enterprise. Among these plant pathogens, viruses are unique in nature and behaviour. As is the case with any seed- transmitted plant pathogens, virus transmission through seeds of higher plants also result from complex interactions between the genetic systems of the host, pathogen and the environment. There is increasing awareness of seed- transmitted viruses with particular reference to their mode of transmission, survival and management. Till date, more than 231 viruses have been reported to be seed transmitted in different food, fiber, weed and ornamental crops. Virus-free seed has assumed multifold significance in quarantine and seed certification for ensuring initial crop health. Circumstantial evidence shows that several viruses have spread to different geographical regions during the process of liberalized seed exchange of crop plants in recent years. Seeds are instrumental in an effective worldwide spread of a range of diseases through international exchange of seeds. The techniques of identification and management of seed-transmitted viruses are completely different from those of other pathogens like fungi, bacteria and phytoplasmas. The information on reliable techniques for detection of seed-transmitted viruses and their management is of immense use in the present international seed trade. The coverage of seed-transmitted plant viruses is limited to few chapters in books on seed pathology. Considerable information in respect of new seed- transmitted viruses, their detection and identification techniques, transmission and management has been generated in recent years. This publication is an endeavor to compile up-to-date literature available on seed-transmitted viruses in a comprehensive form. It is hoped that this book will have an important role to play in the context of the government agencies on new seed policy for liberal import of the seeds of coarse cereals, oilseeds and pulses. The knowledge of seed-transmitted virus diseases on the isolation and identification of viruses in fresh seed lots and their management not only restricts the entry of virus diseases but also will help to prevent the spread

ix x Preface of unrecorded virus diseases in the country. Within the scope of this book, elaborate attempts have been made to present a comprehensive account on identification, mode of transmission, ecology, epidemiology and management of seed-transmitted virus and viroid diseases covered in ten chapters. An up-to-date list of all seed-transmitted viruses and viroids of different host plants is presented in the form of a table for ready reference. The information given on latest molecular techniques for virus detection and management included in this volume will be of immense practical value to researchers and field workers. This work has immensely benefited from critical comments and con- structive suggestions made by Prof. M. V. Nayudu, Dr. S. E. Albrechtsen, Dr. P. Sreenivasulu, Dr. G. P. Rao, Dr. R. K. Khetarpal, Dr. D. V. R. Saigopal, Dr. V. C. Chalam and also assistance offered by our scholarly friends and colleagues. I am highly thankful to all the persons, organizations and various publishers for their prompt help in providing information, photographs and consents for reproduction. I also wish to express my sincere gratitude to Mr. C. Nagaraja for secretarial work. I thank my wife Mrs. B. N. K. Kumari for her continuous support during the preparation of this book. I dedicate this book to the memory of my parents late K. Panduranga Sastry and Smt. K. Subadramma who have sacrificed everything to give me the best education possible and for their eternal blessings. I hope this book will be of value and interest to many teachers, students, seed biologists, seed technologists, seed companies and researchers at quarantine stations as a comprehensive, accurate and easily readable reference book on seed-transmitted plant virus and viroid diseases. I shall deem it an honour and reward if readers find this book useful to them. I welcome suggestions and comments for the improvement of this book in future editions.

K. Subramanya Sastry Contents

1 Introduction ...... 1 1.1 Introduction ...... 1 1.1.1 Seed (Sexual Propagule) ...... 2 1.2 Seed Transmission of Viruses ...... 2 1.2.1 History of Seed-Transmitted Plant Virus Research 4 1.3 Seed Transmission of Partitiviridae ...... 5 1.4 Seed Transmission of Viroids ...... 5 1.4.1 Extent of Seed Transmission ...... 6 1.5 Viruses Erroneously Listed as Seed Transmitted ...... 7 1.5.1 Seed-Transmitted Plant Virus Names That Appeared Only Once in the Literature ...... 8 1.5.2 Establishing Certain Erotic Positive Seed- Transmitted Viruses to Be Non-seed Transmissible 9 References ...... 32 2 Identification and Taxonomic Groups ...... 55 2.1 Identification ...... 56 2.2 Classification of Viruses ...... 56 2.3 Variability in Certain Seed-Transmitted Viruses ...... 62 References ...... 65 3 Economic Significance of Seed-Transmitted Plant Virus Diseases ...... 67 3.1 Introduction ...... 67 3.2 Assessment of Crop Losses ...... 67 3.3 Viruses and Seed Viability ...... 69 3.4 Factors Affecting Yield Losses ...... 69 References ...... 70 4 Virus Transmission ...... 75 4.1 Vector Transmission ...... 75 4.1.1 Aphids ...... 76 4.1.2 Beetles ...... 77 4.1.3 Thrips ...... 77 4.1.4 Whiteflies ...... 78 4.1.5 Mites ...... 78 4.1.6 Nematodes ...... 78 4.1.7 Bumblebees ...... 79

xi xii Contents

4.1.8 Fungi ...... 79 4.1.9 Mealybug ...... 79 4.2 Nonvector Transmission ...... 80 4.2.1 Mechanical Spread ...... 80 4.2.2 Wind ...... 80 4.2.3 Water ...... 80 4.2.4 Obligate Symbiosis ...... 80 4.3 Conclusions ...... 81 References ...... 81 5 Mechanism of Seed Transmission ...... 85 5.1 Embryology and Development of Seed Structures ...... 85 5.2 Distribution of Virus in the Seed ...... 87 5.3 Virus Longevity in Seeds ...... 88 5.4 Genetics of Seed Transmission ...... 88 5.5 Factors Inﬂuencing Rate of Seed Transmission ...... 88 5.5.1 Number of Infection Sources ...... 90 5.5.2 Virus Strain/Isolate ...... 90 5.5.3 Mixed Infections...... 90 5.5.4 Host Species ...... 90 5.5.5 Stage of Infection ...... 92 5.5.6 Environmental Factors ...... 92 5.6 Reasons for Failure of Seed Transmission ...... 93 5.6.1 Inability to Infect Embryos ...... 93 5.6.2 Inability of Virus Survival in the Embryos ...... 94 5.7 Conclusions ...... 95 References ...... 95 6 Detection of Plant Viruses in Seeds ...... 101 6.1 Introduction ...... 101 6.1.1 Seed Health Testing ...... 102 6.1.2 Low Seed Transmission/ Symptomless Carriers . . . 103 6.2 Biological Methods ...... 105 6.2.1 Visual Examination ...... 105 6.2.2 Grow-Out Test ...... 107 6.2.3 Indicator Hosts ...... 108 6.2.4 Biological Properties ...... 109 6.3 Physical Methods ...... 109 6.3.1 Inclusion Bodies ...... 109 6.3.2 Electron Microscopy ...... 111 6.4 Serological Techniques ...... 111 6.4.1 Monoclonal and Polyclonal Antibodies ...... 112 6.4.2 Immunodiffusion Tests ...... 114 6.4.3 Labelled Antibody Techniques ...... 116 6.4.4 Dot-Immunobinding Assay (DIBA or DIA) ...... 126 6.4.5 Disperse Dye Immunoassay (DIA) ...... 128 6.4.6 Rapid Immunoﬁlter Paper Assay (RIPA) ...... 128 6.4.7 Immunosorbent Electron Microscopy (ISEM) .... 129 Contents xiii

6.5 Biotechnology/Molecular Biology-Based Virus Diagnosis . 131 6.5.1 Introduction ...... 131 6.5.2 Molecular Hybridisation ...... 132 6.5.3 Double-Stranded RNA (dsRNA) Analysis ...... 133 6.5.4 Gel Electrophoresis ...... 134 6.5.5 Nucleic Acid-Speciﬁc Hybridisation ...... 135 6.5.6 Array Technologies ...... 137 6.5.7 Polymerase Chain Reaction (PCR)-Based Detection ...... 138 6.5.8 Real-Time PCR ...... 143 6.6 Molecular Markers ...... 144 6.7 Conclusions ...... 145 References ...... 145 7 Ecology and Epidemiology of Seed-Transmitted Viruses ..... 165 7.1 Introduction ...... 166 7.1.1 Primary Inoculum Source ...... 166 7.2 Host Plant ...... 167 7.3 Vectors ...... 170 7.3.1 Factors Inﬂuencing Vector Movement ...... 170 7.4 Pollen Transmission ...... 172 7.4.1 Epidemiological Role of Pollen-Transmitted Viruses ...... 173 7.5 Viruses ...... 177 7.6 Conclusion ...... 178 References ...... 179 8 Methods of Combating Seed-Transmitted Virus Diseases ..... 185 8.1 Introduction ...... 185 8.2 Avoidance of Virus Inoculum from Infected Seeds ...... 186 8.2.1 Removal of Infected Seeds ...... 186 8.2.2 Chemical Seed Disinfection ...... 186 8.2.3 Seed Disinfection by Heat ...... 187 8.2.4 Storage Effect ...... 189 8.2.5 Irradiation Effect ...... 189 8.3 Reducing the Rate of Virus Spread Through Vector Management ...... 189 8.3.1 Avoiding of Continuous Cropping ...... 189 8.3.2 Elimination of Weed, Volunteer and Wild Hosts . . 190 8.3.3 Roguing ...... 190 8.3.4 Crop Rotation ...... 191 8.3.5 Planting Dates ...... 191 8.3.6 Plant Density ...... 191 8.3.7 Barrier and Cover Crops ...... 192 8.4 Integrated Cultural Practices for Seed-Transmitted Virus Disease Management ...... 192 8.5 Crops Hygiene ...... 193 8.5.1 Raising Transplants ...... 194 xiv Contents

8.6 Control of the Vectors ...... 195 8.6.1 Insecticides ...... 195 8.6.2 Mineral Oils ...... 196 8.6.3 Repelling Surfaces ...... 196 8.7 Virus Avoidance ...... 197 8.7.1 Exclusion ...... 197 8.8 Resistance ...... 199 8.8.1 Host Resistance ...... 201 8.8.2 Sources of Resistance ...... 201 8.8.3 Conventional Breeding of Natural Resistance Genes ...... 203 8.8.4 Cultivars with Low Seed Transmission ...... 205 8.8.5 Vector-Resistant Cultivars ...... 206 8.9 Immunisation ...... 207 8.10 Approved Seed Certification Standards ...... 209 8.11 Stages of Seed Multiplication ...... 210 8.12 Inoculum Threshold ...... 210 8.13 International Seed Testing Association (ISTA) ...... 213 8.13.1 Objectives of ISTA ...... 214 8.13.2 ISTA Certificates ...... 214 8.13.3 Conditions for Issuance of ISTA Certificates ..... 214 8.13.4 Accredited Laboratory ...... 215 8.14 Seed Certification Against Plant Virus Diseases ...... 215 8.14.1 The Quality Control by ELISA ...... 216 8.14.2 Certification Schemes Against Crops ...... 217 8.15 Conclusion ...... 220 8.16 Quality Control of Bulk Seed Lots ...... 220 8.16.1 Determination of Seed Transmission Rate ...... 220 8.16.2 Infection Status of a Bulk Seed Lot with Respect to a Tolerance Limit ...... 222 8.16.3 Infection Status of a Bulk Seed Lot with Respect to a Virus Not Known in the Importing Country . . . 222 8.17 World Trade Organization (WTO) Regime and Its Implications ...... 222 8.17.1 Examples of Introduced Plant Viruses Through Seed Exchange ...... 223 8.18 The Role of Plant Biosecurity in Preventing and Controlling Emerging Plant Virus Disease Epidemics . . 223 8.19 Pest Risk Analysis (PRA) ...... 225 8.19.1 Pest and Pathogen Risk Analysis ...... 225 8.19.2 Pest Risk Analysis for Viral Diseases of Tropical Fruits ...... 225 8.20 Biosafety ...... 227 8.20.1 Biosafety Regulations ...... 227 8.20.2 History of Biosafety Protocol and Regulations .... 227 8.20.3 Biosafety Regulations of Asia-Pacific Countries . . 228 8.21 Risks Associated with Genetically Modified Crops ...... 229 Contents xv

8.22 Quarantines ...... 229 8.22.1 Plant Quarantine ...... 230 8.22.2 Plant Quarantine Measures ...... 230 8.22.3 Functions of Plant Quarantine ...... 231 8.22.4 Pathways of Spread of Pests and Pathogens ...... 232 8.22.5 Quarantine Status of Plant Importations ...... 233 8.22.6 Types of Materials Received ...... 233 8.23 Role of FAO/IBPGR in Germplasm Exchange ...... 234 8.23.1 Conceptual Guidelines for Exchange of Legume Germplasm, Breeding Lines and Commercial Seed Lots as Follows ...... 234 8.23.2 The Technical Guidelines for Exchange of Germplasm and Breeding Lines ...... 235 8.23.3 Movement of Germplasm ...... 235 8.24 Steps in Technical Recommendations for Seed Germplasm Exchange in the Country of Origin or Destination ...... 236 8.25 Part of the Planting Material to Be Tested and Post-Entry Quarantine ...... 237 8.26 Exclusion of Exotic Plant Viruses Through Quarantine .... 238 8.26.1 International Scenario ...... 238 8.26.2 National Scenario ...... 239 8.27 Challenges in Diagnosis of Pests in Quarantine ...... 241 8.28 Quarantine for Germplasm and Breeding Material...... 241 8.29 Role of IPGRI and NBPGR in Germplasm Maintenance and Exchange ...... 243 8.29.1 Objectives of NBPGR ...... 243 8.29.2 Methods of Testing at Quarantine Stations ...... 244 8.30 Important Cases of Introduction ...... 246 8.31 Important Diseases Restricted to Some Countries ...... 248 8.32 Effective Methods of Plant Importations ...... 249 8.32.1 Phytosanitary Certiﬁcates ...... 249 8.32.2 Closed Quarantines ...... 249 8.32.3 Quantity of Plant Materials ...... 250 8.32.4 Open Quarantine ...... 250 8.32.5 Examination of Exportable Crops During Active Growth ...... 250 8.32.6 The Intermediate Quarantine ...... 251 8.32.7 Aseptic Plantlet Culture ...... 251 8.32.8 Embryo Culture ...... 252 8.32.9 Use of Shoot Tip Grafting or Micrografting ...... 253 8.33 General Principles for the Overall Effectiveness of Quarantines ...... 253 8.34 Quarantine Facilities ...... 254 8.35 Need for Networking for the Developing Countries ...... 254 8.36 Perspectives ...... 255 8.37 Conclusion ...... 256 8.38 Biotechnology and Virus-Derived Resistance ...... 256 8.38.1 Capsid Protein-Mediated Resistance ...... 257 xvi Contents

8.39 Molecular Approaches ...... 257 8.39.1 Molecular Interactions of Seed-Transmitted Viruses ...... 257 8.39.2 Transgenic Approach ...... 258 8.40 Conclusion ...... 266 References ...... 266 9 Plant Virus Transmission Through Vegetative Propagules (Asexual Reproduction) ...... 285 9.1 Different Vegetative Propagative Plant Materials ...... 286 9.2 Role of Vegetatively Propagated Plant Materials in Virus Spread ...... 286 9.3 Different Virus, Phytoplasma and Viroid Diseases ...... 286 9.4 Virus Transmission ...... 286 9.5 Yield Losses...... 288 9.6 Virus Diagnosis ...... 289 9.7 Vegetatively Transmitted Plant Virus and Virus-Like Disease Management by Certiﬁcation Schemes ...... 291 9.7.1 Success Stories of Production of Virus-Free Plant Propagules ...... 291 9.7.2 Certiﬁcation Schemes ...... 295 9.8 IPGRI’S Role in Controlling Virus Diseases in Fruit Germplasm ...... 296 9.9 Conclusion ...... 296 References ...... 296 10 Future Strategies and Conclusions ...... 307 10.1 Introduction ...... 308 10.2 Plant Virus Management by Integrated Approach ...... 310 10.3 Challenges for the Future ...... 313 References ...... 315

Index ...... 317 List of Standard Acronyms of Plant Virus and Viroids

Virus and viroid names Acronym Abaca mosaic virus AbMV African cassava mosaic virus ACMV Alfalfa cryptic virus ACV Alfalfa mosaic virus AMV Andean potato latent tymovirus APLV Apple chlorotic leaf spot virus ACLSV Apple mosaic virus ApMV Apple scar skin viroid ASSVd Apple stem grooving virus ASGV Arabis mosaic virus ArMV Arracacha virus A AVA Artichoke Italian latent virus AILV Artichoke latent virus ALV Artichoke yellow ringspot virus AYRSV Asparagus virus I AV 1 Asparagus virus II AV 2 Avocado sunblotch viroid ASBV Bamboo mosaic virus BaMV Banana bract mosaic potyvirus BBMV Banana bunchy top virus BBTV Banana streak badnavirus BSV Barley stripe mosaic virus BSMV Barley yellow dwarf virus BYDV Bean common mosaic virus BCMV Bean common mosaic necrosis virus BCMNV Bean pod mottle virus BPMV Bean southern mosaic virus BSMV Bean yellow mosaic virus BYMV Beet 1 alpha cryptovirus BCV-1 Beet 2 alpha cryptovirus BCV-2 Beet 3 alpha cryptovirus BCV-3 Beet mild yellowing virus BMYV Blackeye cowpea mosaic virus BICMV Blackgram mild mottle virus BMMV Blackgram mottle virus BgMV Bramble yellow mosaic virus BrmYMV Broad bean mottle virus BBMV Broad bean stain virus BBSV Broad bean true mosaic BBTMV Broad bean wilt virus BBWV Brome mosaic virus BMV Carnation necrotic ﬂeck virus CNFV Carrot red leaf virus CtRLV (continued)

xvii xviii List of Standard Acronyms of Plant Virus and Viroids

(continued) Virus name Acronym Cassava brown streak virus CBSV Cassava common mosaic virus CsCMV Cauliﬂower mosaic virus CaMV Cherry leaf roll virus CLRV Cherry necrotic rusty mottle virus CNRMV Cherry rasp leaf virus CRLV Chicory yellow mottle virus CYMV Chrysanthemum stunt viroid CSV Citrus exocortis viroid CEVd Citrus mosaic virus CiMV Citrus psorosis virus CPsV Citrus ringspot virus CRSV Citrus tristera virus CTV Citrus variegation virus CVV Citrus yellow mosaic virus CYMV Clover yellow mosaic virus ClYMV Clover yellow vein virus CYVV Cocao necrosis virus CoNV Cocao swollen shoot virus CSSV Cocao yellow mosaic virus CYMV Coconut cadang cadang viroid CCCV Coffee ringspot virus CoRSV Coleus blumei viroid CbVd Cow parsnip mosaic virus CpAMV Cowpea aphid-borne mosaic virus CABMV Cowpea banding mosaic virus CpBMV Cowpea chlorotic mottle virus CCMV Cowpea chlorotic spot virus CpCSV Cowpea green vein-banding virus CGVBV Cowpea mild mottle virus CMMV Cowpea Moroccan aphid-borne mosaic CABMV Cowpea mosaic virus CPMV Cowpea mottle virus CPMoV Cowpea severe mosaic virus CpSMV Crimson clover latent virus CCLV Cucumber cryptic virus CuCV Cucumber pale fruit viroid CPFVd Cucumber green mottle mosaic virus CGMMV Cucumber leaf spot virus CLSV Cucumber mosaic virus CMV Cymbidium ringspot virus CyRSV Dahlia mosaic virus DMV Dapple apple viroid DAV Dasheen mosaic virus DsMV Desmodium mosaic virus DesMV Dioscorea bacilliform virus DBV Echtes Ackerbohnen mosaik viruses EAMV Eggplant mosaic virus EMV Elm mosaic virus EIMV Elm mottle EMoV Euonymus mosaic EuoMV Fescue cryptic virus FCV Fig latent virus 1 FLV-1 Garland chrysanthemum temperate GCTV Garlic common latent virus GCLV Grapevine Bulgarian latent virus GBLV (continued) List of Standard Acronyms of Plant Virus and Viroids xix

(continued) Virus name Acronym Grapevine fanleaf virus GFLV Grapevine yellow speckle viroid GYSV Groundnut bud necrosis virus GBNV Guar symptomless virus GSLV Hibiscus latent ringspot virus HLRSV High plains virus HPV Hop stunt viroid HsVd Hop trefoil cryptic 1 HTCV1 Hop trefoil cryptic 2 HTCV2 Hop trefoil cryptic 3 HTCV3 Hosta virus x HSVX Humulus japonicas virus HJV Hydrangea mosaic virus HdMV Indian cassava mosaic virus ICMV Indian citrus ringspot virus ICRSV Indian peanut clump virus IPCV Iris mild mosaic virus IMMV Iris yellow spot virus IYSV Kalanchoe top-spotting KTSV Leek yellow stripe virus LYSV Lettuce mosaic virus LMV Lilac ring mottle virus LRMV Lucerne Australian latent virus LALV Lucerne (Australian) symptomless LASV Lucerne transient streak virus LTSV Lychnis ringspot virus LRSV Maize chlorotic mottle virus MCMV Maize dwarf mosaic virus MDMV Maize mosaic virus MMV Maize streak virus MSV Melon necrotic spot carmovirus MNSV Melon rugose mosaic virus MRMV Mibuna temperate virus MTV Mulberry ringspot virus MRSV Muskmelon mosaic virus MuMV Muskmelon necrotic spot virus MNSV Nicotiana velutina mosaic virus NVMV Oat mosaic virus OMV Olive latent virus OLV Onion yellow dwarf virus OYDV Panicum mosaic virus PMV Papaya ringspot virus PRSV Paprika mild mottle tobamovirus PaMMV Parsley latent virus PLV Passionfruit woodiness virus PWV Peach rosette mosaic virus PRMV Pea early browning virus PEBV Pea enation mosaic virus PEMV Pea mild mosaic virus PMiMV Pea mosaic virus PMV Peanut clump virus PCV Peanut mottle virus PeMoV Pea streak virus PeSV Peanut bud necrosis virus PBNV Peanut stripe virus PStV Peanut stunt virus PSV (continued) xx List of Standard Acronyms of Plant Virus and Viroids

(continued) Virus name Acronym Pea seed-borne mosaic virus PSbMV Pelargonium zonate spot virus PZSV Pepino mosaic virus PepMV Pepper mild mosaic virus PMMV Pepper mild mottle virus PMMoV Piper yellow mottle virus PYMoV Plum pox virus PPV Potato leaf roll virus PLRV Potato spindle tuber viroid PSTVd Potato virus M PVM Potato virus S PVS Potato virus T PVT Potato virus U PVU Potato virus X PVX Potato virus Y PVY Prune dwarf virus PDV Prunus necrotic ringspot virus PNRSV Radish yellow edge virus RYEV Raspberry bushy dwarf virus RBDV Raspberry ringspot virus RRV Red clover cryptic virus RCCV Red clover mottle virus RCMV Red clover vein mosaic virus RCVMV Red pepper crypticÐ1 RPCV1 Red pepper crypticÐ2 RPCV2 Rhubarb temperate virus RTV Rice yellow mottle virus RYMV Rubus Chinese seed-borne nepovirus RCSV Rye grass cryptic virus RGCV Santosai temperate virus STV Satsuma dwarf virus SDV Soil-borne wheat mosaic virus SBWMV Southern bean mosaic virus SBMV Sowbane mosaic virus SoMV Soybean mild mosaic virus SMMV Soybean mosaic virus SMV Spinach latent virus SpLV Spinach temperate virus SpTV Squash mosaic virus SqMV Strawberry latent ringspot virus SLRSV Subterranean clover mottle virus SCMoV Sugarcane mosaic virus SCMV Sunﬂower mosaic potyvirus SuMV Sunﬂower rugose mosaic virus SRMV Sunn-hemp mosaic virus SHMV Sweet potato feathery mottle virus SPFMV Sweet potato ringspot virus SPRSV Tobacco mosaic virus TMV Tobacco necrosis virus TNV Tobacco rattle virus TRV Tobacco ringspot virus TRSV Tobacco streak virus TSV Tomato apical stunt viroid TASVd Tomato aspermy virus TAV (continued) List of Standard Acronyms of Plant Virus and Viroids xxi

(continued) Virus name Acronym Tomato black ring virus TBRV Tomato bushy stunt virus TBSV Tomato chlorotic dwarf viroid TCDV Tomato mosaic virus ToMV Tomato ringspot virus ToRSV Tomato spotted wilt virus TSWV Tomato streak virus TSV Turnip mosaic virus TuMV Turnip yellow mosaic virus TYMV Urdbean leaf crinkle virus ULCV Vicia cryptic virus VCV Watermelon mosaic virus WMV Wheat soil borne mosaic virus WSBMV Wheat streak mosaic virus WSMV White clover cryptic virus WCCV White clover mosaic virus WClMV Zucchini yellow mosaic virus ZYMV