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Red Blotch Symposium
Recent Advances in Grapevine Red Blotch Virus (GRBV) Vectors and Management
This symposium will provide a comprehensive update on research into all aspects of the grapevine red blotch virus and its impact on the wine industry by leading researchers in their respective fields. Topics will include an overview of the virus and progression, understanding the spread of red blotch disease and identifying the vectors and their biology, improved methods for tracking the disease remotely, mitigating the disease in the vineyard and understanding the impact of the disease on wine composition and sensorial attributes. The symposium promises to include practical advice to counter an insidious disease and will allow participants a chance to taste wines made from grapes infected with the disease as well as appropriate controls.
Symposium Chair: Anita Oberholster, University of California, Davis
Program:
Program is subject to change.
| Overview of Grapevine Red Blotch Virus | ||
| 8:50 am – 9:00 am | Welcome and Introduction to the Symposium Anita Oberholster, University of California, Davis | Oregon Ballroom, Salon F |
| 9:00 am – 9:45 am | Grapevine Red Blotch Virus: Lessons Learned in Seven Years Achala KC, Oregon State University, Central Point | Oregon Ballroom, Salon F |
| Understanding the Spread and Biology of Virus Vectors | ||
| 9:45 am – 10:15 am | Prevalence and Spread of GRBV in California: Impact of Host, Reservoirs and Vectors Mysore Sudarshana, United States Department of Agriculture – Agriculture Research Services, California | Oregon Ballroom, Salon F |
| 10:15 am – 10:30 am | Break | |
| 10:30 am – 11:15 am | Role of Treehoppers in Grapevine Red Blotch Disease Epidemiology Frank Zalom, University of California, Davis | Oregon Ballroom, Salon F |
| 11:15 am – Noon | Integrative Studies of Vector-Related Virus Epidemiology Vaughn Walton, Oregon State University, Corvallis | Oregon Ballroom, Salon F |
| Noon – 1:30 pm | Box Lunch Included | Oregon Ballroom, Salon G |
| Tracking the Disease | ||
| 1:30 pm – 2:15 pm | Spectral and Imaging Features to Predict GRBV Infected Leaves Using AI Models Rewa Rai, University of California, Davis | Oregon Ballroom, Salon F |
| Mitigating the Disease in Vineyard | ||
| 2:15 pm – 3:00 pm | Viticultural Practices to Mitigate the Impact of GRBV on Infected Grapevines in Relation to Fruit Production and Quality Alexander Levin, Oregon State University, Central Point | Oregon Ballroom, Salon F |
| 3:00 pm – 3:15 pm | Break | |
| Impact of Virus on Wine Composition and Sensory (includes tasting) | ||
| 3:15 pm – 4:15 pm | Impact of Grapevine Red Blotch Disease on Grape and Wine Composition and Wine Style Anita Oberholster, University of California, Davis | Oregon Ballroom, Salon F |
| Abstracts Submitted of Current Research on Grapevine Red Blotch | ||
| 4:15 pm – 4:35 pm | Exploring the Host-Pathogen Molecular Interactions Through Multi-OMICs for GRBV Control in Grapevine Christian Mandelli, Oregon State University, Corvallis | Oregon Ballroom, Salon F |
| 4:35 pm – 4:55 pm | Scalable Vine-Level Assessment of Grapevine Red Blotch Virus Infections from Aerial Hyperspectral Images Eve Laroche-Pinel, California State University, Fresno | Oregon Ballroom, Salon F |
| Wrap-up | ||
| 4:55 pm – 5:00 pm | Anita Oberholster, University of California, Davis | Oregon Ballroom, Salon F |
Christian Mandelli | Laurent Deluc
Exploring the Host-Pathogen Molecular Interactions through Multi-OMICs for GRBV Control in Grapevine
Christian Mandelli* and Laurent Deluc
*Oregon State University, 2750 SW Campus Way, Corvallis, OR, 97331
(mandellc@oregonstate.edu)
The lack of targeted approaches to control grapevine red blotch virus (GRBV) through vector management presents a significant challenge to the wine industry. Costly vine removal represents the only effective option, underscoring the urgent need for targeted alternatives. RNA interference (RNAi) is a conserved defense mechanism in plants, triggered by the virus’ presence during early infection stages. Currently, the RNAi-related molecular interactions between GRBV and grapevine are poorly documented. Establishing a solid understanding of the GRBV-host arms race is essential to develop effective control strategies that enhance the RNAi response. Our research aims to investigate these interactions, focusing on the plant’s RNAi response during early GRBV infection stages. After generating a population of GRBV-infected microvine plants through Agrobacterium-mediated infiltration, we observed a peak of viral replicase activity one week postinfection. Subsequent small RNA sequencing revealed the presence of 21, 22, and 24-nucleotide virus-derived small-interfering RNAs (vsiRNAs), indicating RNAi gene silencing activity. Using a custom bioinformatics pipeline, we identified nine GRBV genomic regions, or hotspots, targeted by the plant’s RNAi. Additionally, GRBV-targeted bisulfite sequencing revealed hypermethylation within these hotspots, peaking at 24 days postinfection (dpi), underlining a potential correlation between small RNA production and the methylation of the viral genome. Based on these findings, we evaluated hotspots-derived double-stranded RNAs (dsRNAs) to silence GRBV activity in infected tissue-cultured plants. Our preliminary data suggest a significant reduction of the viral replicase and V3 transcripts abundance at 12 and 24 dpi. Our results demonstrate the efficacy of enhancing RNAi through dsRNA application for GRBV silencing. Evaluation of other target genes is underway. To the best of our knowledge, this is the first report experimentally validating vsiRNAs produced during early GRBV-infection. Our findings underscore the potential of RNAi-based approaches, emphasizing the importance of foundational knowledge in optimizing such strategies for sustainable vineyard practices.
Funding Support: Oregon Wine Board
Eve Laroche-Pinel | Kaylah Vasquez | Madison Flasco | Monica Cooper | Marc Fuchs | Luca Brillante
Scalable Vine-Level Assessment of Grapevine Red Blotch Virus Infections from Aerial Hyperspectral Images
Eve Laroche-Pinel, Kaylah Vasquez, Madison Flasco, Monica Cooper, Marc Fuchs, and Luca Brillante*
*Department of Viticulture and Enology, California State University Fresno, 2360 E Barstow Ave, Fresno, CA, 93740 (lucabrillante@csufresno.edu)
Grapevine red blotch virus (GRBV) poses a significant threat to viticulture, leading to substantial economic losses because infected vines must be removed to prevent further spread. In this study conducted in October 2021 within a 3-ha Cabernet franc vineyard, we employed hyperspectral remote sensing with a drone-mounted camera to enhance efficiency of red blotch virus detection. The hyperspectral camera captured images in 25 spectral bands within the visible to near-infrared (VIS-NIR) domains (520 to 820 nm).
A total of 264 vines were selected randomly and sampled for PCR analysis to confirm the red blotch virus’s presence. Concurrently, images were acquired using the drone and processed through segmentation techniques to extract the vine canopy signal of the selected vines. Additionally, field experts visually inspected the vines to identify infected plants. The accuracies of both the hyperspectral images and the expert assessments were compared to the PCR results.
Six machine-learning models were trained using spectral bands as predictors. Additionally, a radiative transfer model (PROSPECT) was applied in reverse mode to predict leaf pigment concentration (anthocyanins, carotenoids, and chlorophyll) based on vine reflectance, and the output was explored as an alternative set of predictors for detecting vine infections. The overall accuracy reached 87.0% using raw spectral images and 81.4% using the PROSPECT output. The highest feature importance was attributed to the estimated anthocyanin content in leaves.
This preliminary study marks a crucial advancement toward developing an automatic system for the plant-level detection of red blotch-infected vines. Integrating hyperspectral remote sensing, PCR analysis, and machine learning techniques demonstrates promising potential for more efficient and accurate identification and management of red blotch viruses in vineyards.
Funding Support: CDFA SCBGP, CSU ARI, F3, CDFA-PDGWSS
