Advancing Vineyard Health: Insights and Innovations for Combating Grapevine Red Blotch and Leafroll Diseases (2025)
Chapter: Front Matter
Consensus Study Report
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This activity was supported between the California Department of Food and Agriculture (Contract No. AWD-001764) and the National Academy of Sciences. Any opinions, findings, conclusions, or recommendations expressed in this publication do not necessarily reflect the views of any organization or agency that provided support for the project.
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Suggested citation: National Academies of Sciences, Engineering, and Medicine. 2025. Advancing Vineyard Health: Insights and Innovations for Combating Grapevine Red Blotch and Leafroll Diseases. Washington, DC: The National Academies Press. https://doi.org/10.17226/27472.
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COMMITTEE ON ASSISTANCE TO THE CALIFORNIA DEPARTMENT OF FOOD AND AGRICULTURE PIERCE’S DISEASE/GLASSY-WINGED SHARPSHOOTER BOARD ON GRAPEVINE VIRUSES AND GRAPEVINE DISEASE RESEARCH
ANNA E. WHITFIELD (Chair), William Neal Reynolds Distinguished Professor, North Carolina State University, Raleigh
ALEXANDER V. KARASEV (Vice-Chair), University Distinguished Professor, University of Idaho, Moscow
OLUFEMI J. ALABI, Professor and Extension Specialist, Texas A&M University, Weslaco
OZGUR BATUMAN, Associate Professor, University of Florida, Immokalee
ELIZABETH J. CIENIEWICZ, Assistant Professor, Clemson University, Clemson, South Carolina
MAMADOU LAMINE FALL, Research Scientist, Agriculture and Agri-Food Canada, Saint-Jean-sur-Richelieu, Québec; Associate Professor, Université de Sherbrooke, Sherbrooke, Québec
ALANA L. JACOBSON, Associate Professor, Auburn University, Auburn, Alabama
KIRSTEN PELZ-STELINSKI, Professor, University of Florida, Lake Alfred
WENPING QIU, Research Professor, Missouri State University, Mountain Grove
NAIDU A. RAYAPATI, Professor, Washington State University, Prosser
STUART R. REITZ, Professor, Oregon State University, Ontario
THOMAS H. TURPEN, President and CEO, Sensit Ventures, Inc., Davis, California
Study Staff
CAMILLA YANDOC ABLES, Study Director
ROBIN SCHOEN, Board Director
SAMANTHA SISANACHANDENG, Senior Program Assistant
Consultant
ANNE FRANCES JOHNSON, Creative Science Writing
Sponsor
CALIFORNIA DEPARTMENT OF FOOD AND AGRICULTURE
BOARD ON AGRICULTURE AND NATURAL RESOURCES
JILL J. MCCLUSKEY (Chair), Regents Professor and Director of the School of Economic Sciences, Washington State University, Pullman
AMY W. ANDO, Department Chair and Professor, The Ohio State University, Columbus
ARISTOS ARISTIDOU,1 Chief Scientific Officer, Biomason, Inc., Durham, North Carolina
BRUNO BASSO, John A. Hannah Distinguished Professor, Michigan State University, East Lansing
BERNADETTE M. DUNHAM, Professorial Lecturer, George Washington University, Washington, D.C.
JESSICA E. HALOFSKY, Director of the USDA Northwest Climate Hub and the Forest Service Western Wildland Environmental Threat Assessment Center, U.S. Department of Agriculture—Pacific Northwest Research Station, Portland
ERMIAS KEBREAB, Associate Dean of Global Engagement and Director of the World Food Center, University of California, Davis
MARTY D. MATLOCK, Professor, University of Arkansas, Fayetteville
JOHN P. MCNAMARA, Professor Emeritus, Washington State University, Pullman
NAIMA MOUSTAID-MOUSSA, Paul W. Horn Distinguished Professor in Nutritional Sciences and Director of the Obesity Research Institute, Texas Tech University, Lubbock
V. ALARIC SAMPLE, Adjunct Professor, George Mason University, Fairfax, Virginia
ROGER E. WYSE, Founder and Managing Partner, Spruce Capital Partners, San Francisco, California
Staff
ROBIN SCHOEN, Director
CAMILLA YANDOC ABLES, Senior Program Officer
MALIA BROWN, Senior Program Assistant
CYNTHIA GETNER, Senior Finance Business Partner
MITCHELL HEBNER, Research Associate
KARA N. LANEY, Senior Program Officer
ALBARAA SARSOUR, Program Officer
SAMANTHA SISANACHANDENG, Senior Program Assistant
___________________
1 Member of the National Academy of Engineering
Reviewers
This Consensus Study Report was reviewed in draft form by individuals chosen for their diverse perspectives and technical expertise. The purpose of this independent review is to provide candid and critical comments that will assist the National Academies of Sciences, Engineering, and Medicine in making each published report as sound as possible and to ensure that it meets the institutional standards for quality, objectivity, evidence, and responsiveness to the study charge. The review comments and draft manuscript remain confidential to protect the integrity of the deliberative process.
We thank the following individuals for their review of this report:
___________________
1 Member of the National Academy of Sciences
Although the reviewers listed above provided many constructive comments and suggestions, they were not asked to endorse the conclusions or recommendations of this report nor did they see the final draft before its release. The review of this report was overseen by JEFFERY DANGL (NAS),2 University of North Carolina at Chapel Hill, and DONALD ORT (NAS),3 University of Illinois at Urbana-Champaign. They were responsible for making certain that an independent examination of this report was carried out in accordance with the standards of the National Academies and that all review comments were carefully considered. Responsibility for the final content rests entirely with the authoring committee and the National Academies.
___________________
2 Member of the National Academy of Sciences
3 Member of the National Academy of Sciences
Acknowledgments
The committee and staff are grateful to everyone who contributed to the successful completion of this report. We extend our sincere thanks to all who provided information; facilitated and hosted the committee’s site visits and public meetings; and shared their knowledge, perspectives, and insights with the committee: the California Department of Food and Agriculture Pierce’s Disease/Glassy-Winged Sharpshooter (PD/GWSS) Board and their representative Matthew Kaiser and consultant Kristin Lowe; Naidu Rayapati and staff, Washington State University Irrigated Agriculture Research and Extension Center; James Harbertson, Washington State University Wine Science Center; Maher Al Rwahnih and Lauren Port, Foundation Plant Services at the University of California, Davis; Kevin Judkins, Inland Desert Nursery, Inc.; Melissa Hansen and members of the Wine Research Advisory Committee of the Washington State Wine Commission; Kevin Corliss, Ste. Michelle Wine Estates (SMWE) and William Wiles, SMWE’s Columbia Crest Winery; California grape growers, nursery operators, farm and integrated pest management advisors, wine producers, and other wine industry stakeholders; and the webinar and open session speakers (listed in Appendix B).
Producing and releasing this report would not have been possible without the support of the National Academies of Sciences, Engineering, and Medicine’s staff. The study committee and project staff sends its heartfelt gratitude to Lauren Everett, Radiah Rose-Crawford, and Eric Edkin in the Executive Office of the Division on Earth and Life Studies; Cynthia Getner in the Office of the Chief Financial Officer; Nancy Huddleston,
Reece Meyhoefer, and Sydney O’Shaughnessy in the Office of the Chief Communications Officer; and Hannah Fuller in the Office of News and Public Information.
3 CURRENT KNOWLEDGE ON GRAPEVINE LEAFROLL DISEASE
Causal (or Associated) Viruses
Host-Pathogen Interactions and Host Defense Mechanisms
Spatial Distribution and Temporal Spread of GLD
4 GRAPEVINE LEAFROLL AND RED BLOTCH DISEASES: KNOWLEDGE GAPS
Knowledge Gaps in GLRaV-3 and GRBV Diagnostics and Detection
Knowledge Gaps Regarding GLRaV-3 and GRBV Vectors
5 RESEARCH AND ACTIONS THAT MAY YIELD THE MOST PROMISING MANAGEMENT SOLUTIONS
Coordinating Management of Multiple Vectors
Host Plant Resistance to Viruses and Vectors
6 CONSIDERATIONS FOR FUTURE RESEARCH ON GRAPEVINE VIRUSES AND DISEASES
Genetic Pest Management Strategies
Insights and Additional Research Directions from Other Pathosystems
Engaging a Wider Range of Researchers in Addressing Research Needs
Addressing the Need for Longer-Term Studies and Replicability
Knowledge Sharing and Collaborative Research
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Boxes, Figures, and Tables
BOXES
S-3 Recommended Research and Actions for Improving GLD and GRBD Management
2-1 Establishing a Causal Relationship of GRBV in Red Blotch Disease
2-2 Production and Distribution of Clean Grapevines in the United States
5-1 State-of-the-Art Practices: Key Elements for Reliable Grapevine Virus Detection
FIGURES
1-1 Grape-growing regions of California
1-2 CDFA proposal funding process
2-3 Adult S. festinus female (A) and male (B, top and bottom)
2-6 GRBV genome, with ORFs marked in blue
2-8 Schematic description of GRBD management strategies
3-4 General mealybug life cycle
3-5 Graphical representation of the diagnostic methods currently available for detection of GLRaV-3
3-6 Opportunities for managing and mitigating GLD in the wine grape production ecosystem
5-1 An illustration of the supply chain for clean grapevine planting material
TABLES
S-1 Current Knowledge about the Viruses Associated with GLD and GRBD and Their Insect Vectors
3-1 Vectors of GLRaVs in California
4-1 Prioritization of Research to Address Knowledge Gaps
5-1 Prioritization of Research and Actions That May Yield the Most Promising Management Solutions
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Preface
Grapevine leafroll disease (GLD) and grapevine red blotch disease (GRBD) are growing threats to the California wine and wine grape sector, which contributes $73 billion annually to the state’s economy. Our committee was charged with analyzing the current state of GLD and GRBD knowledge and identifying key areas where additional research efforts could reduce the spread and economic impacts of these diseases. During visits to wine grape growing regions, we saw firsthand the impact of these diseases on this important crop. Entire fields and even growing regions of wine grapes displayed the characteristic leaf reddening symptoms, providing a striking demonstration of the extent of the problem. Meetings with growers from multiple regions also highlighted the need for new control measures, as growers expressed frustration over the rapid spread of these diseases, even in newly planted vineyards, and the resulting loss in quality of the product. Given that these viral diseases not only reduce yields but also affect sugars and other aspects of fruit quality relevant to wine flavor profiles, an additional complication is that, due to the complexity of the processing and aging winemaking involves, it can potentially take years to see the true impact of the disease on the final product.
Control of vector-borne viral diseases like GLD and GRBD is complicated by several factors, including the tripartite interaction between the plant host, insect vector, and viral pathogen; the fact that vectors can spread between vineyards and wild areas unhindered; and the lack of effective curative measures for use in the field. The two viruses that are the focus of this study, grapevine leafroll-associated virus 3 (GLRaV-3) and grapevine red blotch virus (GRBV), share some similarities but also have
distinct biological features. GLRaV-3 is an ongoing threat to wine grape production in California and globally. An increase in leafroll disease pressure in California was associated with the introduction of the invasive vine mealybug, Planococcus ficus, which is an effective vector and has high reproductive capacity, although other mealybugs are effective vectors and have importance in some wine grape production areas of California. While GLD is an existing and increasing threat to California wine grape production, red blotch is a more recently identified virus disease that needs further characterization at the molecular and ecological levels. In contrast to the mealybug vectors of GLRaV-3, the treehopper vector of GRBV appears to have a transient association with wine grapes. Control of both pathosystems requires detailed knowledge of vector biology and strategies for effective areawide pest management. For this report, we have attempted to identify commonalities and areas where control efforts extend to both systems, as well as distinctive features and areas of needed research that require further inquiry and unique interventions.
Our committee’s approach to this study included extensive information-gathering sessions that involved site visits to vineyards, nurseries, and clean plant centers and meetings with growers, diverse groups of scientists, and extension specialists. We thank the many people who contributed to the report by hosting us, providing space for meetings and tours, or sharing their knowledge. We have acknowledged the expert scientists who addressed the committee’s questions in Appendix B.
We owe an enormous thanks to the Study Director, Dr. Camilla Yandoc Ables. Her extensive knowledge of plant pathology, expert guidance, and friendly demeanor enabled the committee to complete the challenging task of addressing the needs for two different pathosystems. Dr. Ables’s expert management skills created a supportive and open environment that enabled the committee to focus on the task. We also thank Samantha Sisanachandeng, Senior Program Assistant, for her assistance with meetings throughout the study and her positive and friendly attitude, which made the work of the committee go smoothly. We thank Robin Schoen, Director of the National Academies’ Board on Agriculture and Natural Resources for astute and thoughtful advice throughout the study. We also recognize the significant efforts of the California Department of Food and Agriculture Pierce’s Disease/Glassy-Winged Sharpshooter (PD/GWSS) Board representative Matthew Kaiser and consultant Kristin Lowe, who answered many committee questions and facilitated necessary meetings.
In closing, we extend an enormous thanks to the members of the committee. The assembled team worked for more than 18 months to address three tasks. They delved into the literature, drew from their own experiences, and explored new scientific realms to document what is known about GLD and GRBD and what might be possible for their effective
control. Throughout the study, they gave their time as volunteers, and they all contributed to creating a collegial and supportive environment that made this study an enriching experience scientifically and personally. The committee was motivated by the goal of providing tangible and forward-thinking solutions for these emerging diseases, and this common goal and mutual respect enabled sustained energy and focus during the study. We speak for the committee when we express hope that the science-based and experience-informed findings, conclusions, and recommendations in this report will provide the PD/GWSS Board with a pathway toward controlling vector-borne viruses of grapevines.
Anna E. Whitfield, Chair
Alexander V. Karasev, Vice Chair
Committee on Assistance to the California Department of Food and Agriculture Pierce’s Disease/Glassy-Winged Sharpshooter Board on Grapevine Viruses and Grapevine Disease Research
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Acronyms and Abbreviations
| AAP | acquisition access period |
| ACP | Asian citrus psyllid |
| AI | artificial intelligence |
| AWM | areawide pest management |
| BBN | Bayesian Belief Network |
| BYV | beet yellows virus |
| CDFA | California Department of Food and Agriculture |
| cDNA | complementary DNA |
| CP | coat protein |
| CPB | Colorado potato beetle |
| CPm | minor capsid protein |
| CRISPR | clustered regularly interspaced short palindromic repeats |
| CTV | citrus tristeza virus |
| DAVN | Diagnostic Assay Validation Network |
| dLAMP | digital LAMP |
| DMS | differential mobility spectrometry |
| dsRNA | double-stranded RNA |
| ELISA | enzyme-linked immunosorbent assay |
| EN | electronic nose |
| EPF | entomopathogenic fungi |
| EVCWG | Emerging Viruses in Cucurbits Working Group |
| FPS | University of California, Davis Foundation Plant Services |
| GFLV | grapevine fanleaf virus |
| GLD | grapevine leafroll disease |
| GLRaVs | grapevine leafroll-associated viruses |
| GRBD | grapevine red blotch disease |
| GRBV | grapevine red blotch virus |
| GVA | grapevine virus A |
| GWSS | glassy-winged sharpshooter |
| HLB | Huanglongbing |
| HP | high priority |
| hpRNA | hairpin RNA |
| HSP | heat shock protein |
| HTS | high-throughput sequencing |
| IAP | inoculation access period |
| IC-PCR | immunocapture PCR |
| IPC | individual protective cover |
| IPM | integrated pest management |
| LAMP | loop-mediated isothermal amplification |
| L-Pro | leader papain-like protease |
| MP | medium priority |
| mRNA | messenger RNA |
| NCPN | National Clean Plant Network |
| ORF | open reading frame |
| OTC | oxytetracycline |
| PCR | polymerase chain reaction |
| PD | Pierce’s disease |
| PD/GWSS Board | Pierce’s Disease/Glassy-Winged Sharpshooter Board |
| pgSIT | precision guided sterile insect technique |
| PNA-LNA | peptide nucleic acid-locked nucleic acid |
| QGB | quintuple gene block |
| qPCR | quantitative PCR |
| qRT-PCR | quantitative RT-PCR |
| RACE | random amplification of complementary DNA ends |
| RCA | rolling circle amplification |
| RdRP | RNA-dependent RNA polymerase |
| RFP | Request for Proposals |
| RGB | replication gene block |
| RNAi | RNA interference |
| RPA | recombinase polymerase amplification |
| rRNA | ribosomal RNA |
| RT-PCR | reverse transcription PCR |
| RT-RPA | reverse transcription RPA |
| sgRNA | sub-genomic RNA |
| ssDNA | single-stranded DNA |
| TCAH | three-cornered alfalfa hopper |
| TSWV | tomato spotted wilt virus |
| USDA | U.S. Department of Agriculture |
| UV-C | ultraviolet light |
| VOC | volatile organic compound |
| WCR | western corn rootworm |
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Glossary
| Acquisition access period | Total time that an insect vector has been kept on the infected plant to acquire the virus |
| Acquisition | The uptake of virus by an insect vector from an infected source |
| Anthocyanins | Water-soluble compounds (flavonoids) that provide red, magenta, purple, and blue color to the fruit and flowers of many plants |
| Areawide pest management | An approach for reducing pests by uniformly applying pest mitigation measures over geographical areas instead of using a field-by-field approach |
| Bayesian Belief Network | A probabilistic graphical model that captures both conditionally dependent and conditionally independent relationships between random variables; employed to infer and estimate the likelihood of causal or subsequent events |
| Circulative, non-propagative transmission | Viral transmission characterized by longer acquisition and inoculation access periods (hours to days) and longer retention time in the body of the vector |
| Clade | A group of organisms believed to have evolved from a common ancestor |
| Closterovirus | Genus of phloem-associated RNA viruses in the family Closteroviridae |
| Coat protein | The protective outer shell of a virus particle (also referred to as a capsid) |
| CRISPR | Clustered regularly interspaced short palindromic repeats, a technology used to selectively modify the DNA of living organisms (gene editing) |
| CRISPR/Cas12a | An RNA-guided endonuclease that forms part of the CRISPR system and is utilized as a genome editing tool (molecular scissor) to selectively modify the DNA of living organisms |
| Cross-protection | The use of a mild virus strain to infect a plant to protect it from subsequent infection by a more aggressive strain of the same virus that causes severe symptoms or damage |
| Degree days | Heat units required for crop or insect development |
| Digital loop-mediated isothermal amplification (dLAMP) | A technique used for sensitive detection of nucleic acid targets in virus diagnosis |
| Diapause | The period of delayed development in response to adverse environmental conditions |
| Dimorphic | Condition in which males and females of the same species differ in their morphological characteristics, particularly characteristics that are not directly involved in reproduction |
| Electronic nose (EN) | An electronic sensing device intended to detect odors or flavors |
| Enzyme-linked immunosorbent assay (ELISA) | A test that detects viral infection through the interaction between antigens (virus protein) and antibodies (blood protein produced in response to an antigen) in a laboratory setting |
| Endosymbiont | An organism living symbiotically (equal dependency) inside the cells or body of another organism |
| Etiology | The cause or origin of a disease |
| Fecundity | The reproductive rate of an organism |
| Flavonols | A class of flavonoids that serve as building blocks of proanthocyanins that occur in a variety of fruits and vegetables; intake of flavonols is associated with a wide range of health benefits |
| Geminivirus | A term used to broadly describe members of the Geminiviridae, a family of plant viruses that encode their genetic information on a circular genome of single-stranded DNA |
| Genome editing | A genetic engineering technique in which DNA is deleted, inserted, modified, or replaced at site-specific locations in the genome of a living organism |
| High-throughput sequencing (HTS) | A method involving sequencing multiple DNA molecules in parallel, enabling hundreds of millions of DNA molecules to be sequenced at a time (also referred to as next-generation sequencing) |
| Host factors | The aspects of infectious disease transmission that are inherent in the potential host |
| Host plant resistance | The inherent ability of a plant to resist infection by pathogens or damage by pests; the mechanisms of resistance to insects are non-preference or anti-xenosis (the host plant produces stimuli that repel pests or fail to produce stimuli that attract pests), antibiosis (the host plant causes injury, death, or reduced longevity or reproduction of the pest), and tolerance (the host plant can endure pest damage and yield well despite the damage) |
| Hyperspectral imaging | A technique that involves the use of an imaging spectrometer (i.e., hyperspectral camera) to collect and process spectral information, allowing for the identification of objects (e.g., infected plants) by analyzing their unique spectral signatures |
| Imaging spectroscopy | The simultaneous acquisition of spatially co-registered images in many spectrally contiguous bands; this technology includes both hyperspectral imaging and multi-spectral imaging, which differ in the number and the spectra of electromagnetic radiation that each band contains |
| Immunocapture polymerase chain reaction (IC-PCR) | A virus detection technique that combines serology and nucleic acid amplification by using antibodies to capture viruses out of virus-containing plant extracts as a preparatory step to provide the template for PCR detection, thus resulting in higher virus detection specificity and sensitivity |
| Incubation period | The time from infection to the first appearance of symptoms |
| Inoculation access period | The time required for a viruliferous (virus-carrying) vector to introduce the virus to a healthy plant |
| Inoculation | Part of the virus transmission process wherein the virions are delivered by an insect vector (or via other means) to the site of infection |
| Instar | In arthropods, such as insects, the developmental stage between two successive molts |
| Interdisciplinary approach | An approach that involves integration of knowledge and methods from different disciplines to create a holistic approach to a problem |
| Isolate | A virus obtained (isolated) from a single infected host |
| Latency period | In plants, the interval during the course of a disease between when the plant is infected by a pathogen and when that plant becomes infectious (i.e., becomes the source of virus inoculum) |
| Lateral flow assays | Tests used to detect the presence of target molecules in a liquid sample without the need for specialized and costly equipment |
| Long-read sequencing | A DNA sequencing method that produces longer sequence reads (i.e., tens to thousands of kilobases in length); also known as third-generation sequencing |
| Loop-mediated isothermal amplification (LAMP) | A single-tube technique for DNA amplification that is designed primarily for diagnostics; involves the formation of magnesium pyrophosphate precipitate as an indicator that amplification has occurred |
| Mating disruption | An insect pest management technique that uses artificial stimuli (e.g., synthetic sex pheromone) that confuse individuals and disrupt mate location or courtship to block the insect’s reproductive cycle |
| Monopartite | A type of viral particle formed by a single nucleic acid molecule protected by a coat made of proteins (and sometimes also lipids) |
| Multidisciplinary approach | An approach that involves multiple disciplines working independently to address the same problem |
| Neonicotinoid | A class of synthetic systemic insecticides derived from nicotine |
| Non-coding RNAs | Functional RNA molecules that are not translated into proteins |
| Nymph | An immature stage of an insect that undergoes gradual change until it reaches the adult stage |
| Open reading frame (ORF) | A portion of a DNA sequence that does not include a stop codon (which functions as a stop signal) and can potentially be translated into a protein |
| Peptide nucleic acid-locked nucleic acid (PNA-LNA) mediated loop-mediated isothermal amplification (LAMP) | A highly specific method for the detection of low mutant KRAS Q12 and Q13 in a large excess of wild-type DNA |
| Polymerase chain reaction (PCR) | A temperature-dependent nucleic acid amplification technique used to enzymatically amplify a specific DNA segment in vitro |
| Polyphagous | Ability of an insect to feed on plants that belong to diverse taxonomic groups |
| Quantitative polymerase chain reaction (qPCR) | A PCR-based technique (also known as real-time PCR) that allows for monitoring of the amplification of a target DNA segment, thus allowing for its quantification |
| Random amplification of complementary DNA ends (RACE) assay | An assay that facilitates the amplification of genome segments between a specific internal region and the extremities (5′ or 3′ end) of the messenger RNA |
| Reproductive diapause | A suspension of reproductive functions in adult insects |
| Resistance (host) | Ability of the plant host to impede or halt the pathogen’s growth and/or development; the ability of the host plant to prevent or reduce damage caused by insect pests (see also Host plant resistance) |
| Retention | Part of the virus transmission process wherein the acquired virions are retained at requisite sites within the insect vector |
| RNA silencing | The process in which RNA molecules are involved in the sequence-specific suppression of gene expression by double-stranded RNA (also referred to as RNA interference) |
| Rolling circle amplification (RCA) | An isothermal enzymatic process in which a short nucleic acid primer is amplified to form a long, single-stranded nucleic acid using a circular template and special nucleic acid polymerases |
| Recombinase polymerase amplification (RPA) | A single-tube isothermal alternative technique to PCR that requires minimal sample preparation and is capable of amplifying as few as 1 to 10 DNA target copies in less than 20 minutes |
| Reverse-transcription polymerase chain reaction (RT-PCR) | A technique in which reverse transcriptase enzyme is used to convert RNA to cDNA (i.e., complementary DNA), which is then used as a template for amplification in PCR |
| Reverse-transcription recombinase polymerase amplification (RT-RPA) | A technique in which a reverse transcriptase enzyme is added to an RPA reaction, enabling it to detect RNA and DNA without the need for a separate step to produce cDNA |
| Semi-persistent transmission | Mode of transmission wherein plant viruses are retained in the vector foreguts or salivary glands but cannot spread to salivary glands |
| Serological assay | A test used for identifying viral infections by using antibodies (blood proteins) to specifically react with the antigens (viral proteins) against which the antibodies were produced |
| Source/sink balance | A conceptual framework for understanding how crop yield is regulated by source activity and sink demand; source organs are photosynthetically active plant parts where carbohydrates (assimilates) originate (typically, sunlit mature leaves but also includes any carbon-exporting organs); sink organs are non-photosynthetic plant parts that do not produce enough assimilates to meet their growth or maintenance requirements (e.g., developing fruits or berries, roots, or immature leaves) and must import assimilates from sources |
| Squash-blot | A diagnostic technique wherein the tissue of a plant that is suspected to be diseased is crushed onto a membrane (sample), which is then treated with a probe that can bind with the DNA or RNA of the suspected pathogen; subsequent treatment of the bound membrane with other reagents would result in a color reaction if the target pathogen is present or no color reaction if the pathogen is absent in the sample |
| Tolerance (host) | The ability of the plant host to endure infection by the pathogen or insect infestation without incurring serious damage or yield loss |
| Transgenic resistance | Resistance to pests, diseases, or environmental stress that is conferred to a plant via genetic engineering (i.e., transferring specific genes from a different species into the plant’s genome) |
| Transtadially | The sequential passage of parasites acquired during one life stage, or stadium, through the molt to the next stage(s) or stadium |
| Trap crop | A plant that is grown to attract, divert, intercept, and retain pests to reduce damage to the main crop |
| Variant | A virus with new mutations (change in genetic sequence) |
| Vector competence | The ability of a vector to acquire and subsequently transmit a pathogen |
| Vector population replacement | A strategy for reducing vector competence by replacing existing vectors with genetically modified insects that cannot transmit pathogens |
| Vector population suppression | A strategy for reducing the insect vector population by releasing sterile males to compete with wild-type males for mating |
| Veraison | The onset of berry ripening in wine grapes when wine grapes change color and start to soften, expand, and become sweet |
| Virion | A virus particle consisting of an outer protein shell (capsid) and an inner core of nucleic acid (either DNA or RNA) |
| Virome | The total collection of viruses in and on an organism |
| Viruliferous | Containing, producing, or conveying a virus |
| Volatile organic compound (VOC) | An organic substance that easily evaporates at normal temperatures |
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