Source: UNIVERSITY OF ARKANSAS submitted to NRP
MANAGING EMERGING TOMATO BROWN RUGOSE FRUIT VIRUS IN GREENHOUSE TOMATOES USING ALTERNATIVE ROOTSTOCK AND DISINFECTION
Sponsoring Institution
National Institute of Food and Agriculture
Project Status
ACTIVE
Funding Source
OTHER GRANTS
Reporting Frequency
Annual
Accession No.
1030958
Grant No.
2023-70006-40603
Cumulative Award Amt.
$323,001.00
Proposal No.
2023-02996
Multistate No.
(N/A)
Project Start Date
Sep 1, 2023
Project End Date
Aug 31, 2026
Grant Year
2023
Program Code
[ARDP]- Applied Research and Development Program
Recipient Organization
UNIVERSITY OF ARKANSAS
(N/A)
FAYETTEVILLE,AR 72703
Performing Department
(N/A)
Non Technical Summary
This CPPM project is a Research-led proposal to address an important emerging disease - tomato brown rugose fruit virus (ToBRFV) that is threatening the entire $2 billion U.S. tomato industry and the important vegetable seed industry. With the lack of commercial tomato cultivars with resistance to ToBRFV, an integrated pest management approach is currently the best strategy to manage this emerging virus. Since ToBRFV is a seedborne pathogen and can be efficiently transmitted to new germinating seedlings, developing effective seed treatment methods using chemical disinfectants or cold plasma ozone against ToBRFV would be very beneficial prevention measure. Under greenhouse hydroponic production, tomato plants are typically grafted onto a tomato rootstock. With a hydroponic irrigation system in greenhouse tomato production, it is possible that ToBRFV can be transmitted through a recirculating irrigation system to cause a new infection. Unfortunately, a rootstock with a tomato genetic background is susceptible to ToBRFV. However, eggplant has been shown to be a nonhost for ToBRFV in our recent host range evaluation. Eggplant is used extensively in Asian countries for tomato grafting to control soil-borne diseases, however it has not been used extensively for greenhouse tomato production. Therefore, we are interested in evaluating the effect of eggplant-grafted tomato plants to prevent the spread of ToBRFV in greenhouse conditions. The ultimate goal of this proposed project is to develop an integrated pest management system that would provide growers the effective tools to manage this emerging disease caused by ToBRFV in greenhouse tomatoes.
Animal Health Component
60%
Research Effort Categories
Basic
20%
Applied
60%
Developmental
20%
Classification

Knowledge Area (KA)Subject of Investigation (SOI)Field of Science (FOS)Percent
2161460110185%
2021460310015%
Knowledge Area
216 - Integrated Pest Management Systems; 202 - Plant Genetic Resources;

Subject Of Investigation
1460 - Tomato;

Field Of Science
1101 - Virology; 3100 - Management;
Goals / Objectives
With the emergence of ToBRFV, a resistant-breaking tobamovirus to the popular resistance gene Tm-22, all commercial tomato cultivars are currently susceptible to ToBRFV infection. Although the reported outbreaks of ToBRFV are primarily limited to greenhouse productions, a recent report from Florida showed an outbreak of ToBRFV in a community garden (Dey et al., 2021) and on tomato fruits from retail stores in several states (FL, MD, MI, and NE) (Abrahamian et al., 2022), suggesting the spread of the virus may have gone far beyond what we currently known. Due to seed-borne and ease of mechanical transmission of the virus, the chance of its spread to field tomato production is high, which poses severe threat to the $2 billion U.S. tomato industry. In addition to tomato, ToBRFV can infect many other solanaceous plants, including pepper and tobacco. Because of these reasons, USDA-APHIS issued a Federal Order on ToBRFV in 2019 to inspect imported tomato and pepper to prevent the induction of ToBRFV to the U.S. from foreign countries.The ultimate goal of this proposed project is to develop an integrated pest management system that would provide growers with effective measures to manage this emerging disease caused by ToBRFV. The specific objectives of this research are to: 1). Evaluate the ToBRFV-resistant wild tomato Solanum pimpinellifolium (USDA332) as a rootstock for tomato grafting; 2). Evaluate eggplant, a non-host for ToBRFV as an alternative rootstock, for tomato grafting to prevent ToBRFV transmission; 3). Develop effective seed treatment using thermal or chemotherapy methods to inactivate ToBRFV-contaminated tomato seeds; 4). Evaluate cold plasma ozone treatment for greenhouse disinfection against ToBRFV contamination in recirculating irrigation water; and 5). Implement integrated pest management strategy for ToBRFV control and conduct outreach, education and extension to tomato growers in the U.S. In collaboration with greenhouse tomato growers, an integrated pest management approach by incorporating various technologies and tools that have been developed above will be implemented in greenhouse tomato production. Extension and education efforts will be conducted throughout the program as data become available and relevant to the greenhouse tomato growers. An extension website will be created to house those extension materials and for greater dissemination. Reports will be made available in scientific meetings, workshops and formal publications.
Project Methods
Objective 1. To evaluate the ToBRFV-resistant wild tomato Solanum pimpinellifolium (USDA332) as a rootstock for tomato grafting.Evaluation of graft compatibility between scions and rootstock: 'USDA332', a Solanum pimpinellifolium germplasm with ToBRFV-resistance, and commercial rootstock 'Maxifort' will be served as a rootstock and 'Moneymaker' and 'Paipai' will be grafted to the two rootstocks. Grafting methods will be assessed to determine which one is the most robotic.Evaluation of grafted tomato plants for resistance to ToBRFV transmission: The grafted plants above will be watered with ToBRFV-contaminated water solution. Those combinations of grated plants with low to no ToBRFV infection and in the highest yield will be recommended for field trials in collaborating greenhouse tomato growers.Field trials to access the wild tomato rootstock to prevent transmission of ToBRFV to scion tomato cultivars. Field trials will be carried out in collaborating greenhouse growers who have experienced ToBRFV infections. Confirmation of a positive virus infection will be performed by sending the tissue samples from the growers to Ling's lab for testing. Yield will be measured on each block of plants after each harvesting. Data on infection rate and the fruit yield produced from each block will be measured and analyzed statistically using SAS ANOVA with randomized complete block design.Objective 2. To evaluate eggplant, a non-host for ToBRFV, as an alternative rootstock for tomato grafting to prevent ToBRFV transmission (Research)Eggplant, a non-host for ToBRFV, will be used as a rootstock for tomato grafting to control ToBRFV. The first step is to evaluate and select eggplant varieties that have strong graft compatibility with tomato scion as well as the vigor to support greenhouse tomato production. Two eggplant accessions EG195, EG203, and 10 additional eggplant varieties that will be included in the test. If the greenhouse test was shown to be effective in breaking the ToBRFV disease cycle, a field trial will be conducted in the collaborating grower's greenhouse, which was previously shown to be infected by ToBRFV. Disease incidence and yield improvement on those tomato plants grafted to eggplant or tomato rootstock will be assessed using appropriate statistical analysis.Objective 3. To develop effective seed treatment using thermal or chemotherapy methods to inactivate ToBRFV-contaminated tomato seeds. (Research)ToBRFV is a seed-borne pathogen and the virus particles can be easily transmitted to seedlings to trigger a new infection. Seed health testing on ToBRFV can reduce the incidence of contaminated seeds. Seed treatment would add another layer of protection to ensure any remains of ToBRFV contamination on the seed could be reduced or eliminated. Thermal therapy with dry heat at 75 to 80 °C for dry heat baking for 48 to 72 hours is effective to inactivate ToBRFV on contaminated tomato seeds.Bioassay will be used to assess the effectiveness of each seed treatment method by comparing seeds before and after thermal treatment. The efficacy of each treatment will be assessed through a bioassay in a greenhouse through mechanical inoculation of treated seed extract on tomato seedlings and observation of symptom expression on the tested plants, which will be followed by a confirmation test (ELISA for ToBRFV) for the presence of the virus. Using experimental tomato seeds generated in Ling's lab with high contamination rate for ToBRFV, seed treatment will be conducted by soaking a contaminated seed lot with 2% contamination rate (using 2 ToBRFV-seeds in 100 healthy seeds) in a series of different concentrations of chemicals, 2-4% Virocid, 20-50% Clorox bleach solutions, 2-4% Virkon S and 5-10% TSP (trisodium phosphate) for various durations (30, 60 or 120 min). The best seed treatment methods with full inactivation of virus infectivity on the contaminated seeds without adverse effect on seed germination will be selected and recommended to growers and seed companies for adaptation and implementation.Objective 4. To evaluate cold plasma ozone treatment for greenhouse disinfection against ToBRFV contamination in recirculating irrigation water. (Research)Although growers are starting to use some of the effective disinfectants as a part of sanitization and disinfection practices against ToBRFV infection in greenhouse tomato production, there is a special concern that virus particles could contaminate the water source, which circulates through the hydroponic nutrient irrigation systems and triggers infections on other tomato plants. To inactivate virus infectivity in the irrigation system, we are currently working with a partner company to evaluate the effectiveness of cold plasma ozone treatment against ToBRFV exists in irrigation water. First, we will develop a simple means to evaluate whether different dosages of ozone for treatment periods are capable of inactivating ToBRFV infectivity in various levels of ToBRFV-contaminated water. The efficacy will be assessed using a bioassay by mechanical inoculating each treated materials on six tomato 'Moneymaker' seedlings and through observing whether inoculated plants will develop disease symptoms.Tested plants maintained in a containment greenhouse at USDA-ARS Charleston, SC for symptom expression at 4 weeks post inoculation. Confirmation tests for the presence of ToBRFV by using a serological test using a ToBRFV ELISA kit. Data will be analyzed using an appropriate statistical analysis package. Objective 5. To implement integrated pest management strategy for ToBRFV control and conduct outreach, education and extension to tomato growers in the U.S. To implement integrated pest management (IPM) strategies for ToBRFV control and outreach, extension and education to tomato growers in the U.S. (Extension). Selecting a clean and ToBRFV test-negative seedlot is the first step, following by seed treatment using appropriate thermal or chemotherapy. Planting tomato plants that are grafted on ToBRFV-resistant wild tomato or an eggplant rootstock (a non-host resistance to ToBRFV), which would break the disease cycle on virus inoculum that may be introduced from the ToBRFV-contaminated recirculating hydroponic water solution. Finally, ozone treatment on recirculating water system will offer additional protection. By incorporating these IPM approaches, we will likely bring this emerging disease under control.With the leadership from a major greenhouse tomato grower (Village Farms), we have established a network of major greenhouse tomato growers in the U.S. and Canada since 2020 and regularly (weekly to monthly) conducted growers' meetings (ARS-hosted ToBRFV virtual workshop for PROCINORTI-2020, ToBRFV Research Symposium of 2022, and Canadian Greenhouse Conference-2022) to update research results on disinfectants, other relevant scientific information or technologies. We will continue this educational opportunity to communicate directly with greenhouse tomato growers. We will also attend and present the research progress and results in annual Tomato Disease Workshop, Tomato Breeders Round Table, America Seed Trade Association (Vegetable and Flower -tech subcommittee), and other national and international meetings. We will also supply information and work closely with crop IPM consultants to develop extension bulletins and communication for further dissemination.

Progress 09/01/23 to 08/31/24

Outputs
Target Audience:During this reporting period, the target audiences reached included greenhouse tomato growers from the U.S. and Canada, nursery operators, vegetable seed producers affiliated with the American Seed Trade Association, Federal and state government regulators, as well as researchers and extension personnel. Changes/Problems: Nothing Reported What opportunities for training and professional development has the project provided?Co-PD Ling was invited to organize a special session at the 2023 International Congress of Plant Pathology, focusing on the re-emergence of tobamoviruses and their threat to global vegetable production. Additionally, he has been invited to present at three national and three international meetings, further contributing to the dissemination of knowledge and professional development in the field. How have the results been disseminated to communities of interest?Co-PD Ling is frequently consulted--nearly on a weekly basis--by various greenhouse tomato growers and seed health testing companies. The results have also been disseminated through two peer-reviewed publications in open-access journals, making them freely available to both researchers and the general public. Additionally, presentations at six national and international meetings have reached a broad audience, including researchers, tomato growers, and seed producers. What do you plan to do during the next reporting period to accomplish the goals?A new postdoc has been hired through the University of Arkansas and will work in Ling's lab at the USDA-ARS facility in Charleston. During the next reporting period, we plan to carry out all major activities outlined in the proposal. This includes evaluating the ToBRFV-resistant wild tomato Solanum pimpinellifolium (USDA332) and the non-host eggplant as rootstocks for tomato grafting. We will also conduct seed treatment trials for ToBRFV on tomato. In collaboration with growers, we plan to implement cold-plasma ozone treatment. Finally, we will continue to present our findings at various meetings, growers' associations, and seed trade associations.

Impacts
What was accomplished under these goals? Evaluation of ToBRFV-Resistant Wild Tomato Solanum pimpinellifolium (USDA332) as a Rootstock for Tomato Grafting To assess graft compatibility using the Solanum pimpinellifolium germplasm USDA332 as a ToBRFV-resistant rootstock, we first needed to increase seed material in our containment greenhouse. Since S. pimpinellifolium is not self-pollinating, we generated 100 fruits through hand-pollination, extracting at least 5,000 seeds. These seeds will be used as rootstock for grafting to tomato cultivars in the coming year and for evaluating their performance against ToBRFV infection. Evaluation of Eggplant as an Alternative Rootstock for Tomato Grafting to Prevent ToBRFV Transmission As eggplant is a new rootstock for tomato grafting, we first evaluated the grafting process using eggplant 'Black Beauty' in a controlled environment. We successfully generated grafted plants, but the initial survival rate was less than 50%. In the coming year, we aim to improve the environmental conditions, particularly by increasing humidity in the healing chamber during the first week post-grafting and gradually increasing light intensity to strengthen the graft union. Development of Effective Seed Treatment Methods to Inactivate ToBRFV-Contaminated Tomato Seeds To develop seed treatments, we first needed a large number of ToBRFV-contaminated seeds. During the year from 2023 to 2024, we grew over 10 ToBRFV-infected tomato plants in our containment greenhouse, producing more than 10,000 contaminated seeds. These seeds will be used in the initial seed treatment experiments planned for the coming year. Evaluation of Cold Plasma Ozone Treatment for Greenhouse Disinfection Against ToBRFV in Recirculating Irrigation Water Significant progress was made in evaluating cold plasma ozone treatment for ToBRFV in contaminated water, resulting in a peer-reviewed publication. We demonstrated that ToBRFV is infectious and transmissible through recirculating hydroponic systems in a commercial tomato greenhouse. The cold plasma ozone treatment's effectiveness was assessed, showing that it depends on ozone concentration, exposure time, and virus titers. The results suggest that cold plasma ozone treatment is a promising method for treating ToBRFV in contaminated hydroponic systems. Implementation of Integrated Pest Management (IPM) Strategies for ToBRFV Control and Outreach to Tomato Growers Research accomplishments on ToBRFV management were presented at several national and international meetings, including the 12th International Congress of Plant Pathology in Lyon, France; the 2023 Tomato Disease Workshop at Purdue University; the 2024 International Symposium on Tomato Disease in Brasilia, Brazil; and the 2024 Canadian Greenhouse Conference in Niagara Falls, Canada. Additionally, Ling was frequently consulted by USDA-APHIS, greenhouse growers, seed companies, and nursery operators regarding ToBRFV management.

Publications

  • Type: Conference Papers and Presentations Status: Published Year Published: 2024 Citation: 3. K.-S. Ling, J. Zhou, N. Jaiswal, B. Chanda, B. Zia, A. Gilliard, and A. Shi. 2024. Tomato Brown Rugose Fruit Virus Genetic Diversity, Transmission, and Management. 2024 American Seed Trade Association (ASTA), Vegetable and Flower Technical Sub-Committee (VFTSC) Spring Meeting. January 23, 2024. 4. J. Zhou, A. Gilliard, J. Tung, S. P. Dinesh-Kumar, S. A. Whitham, B. Baker and K.-S. Ling. 2024. N NLR-mediated resistance to tomato brown rugose fruit virus in transgenic tomato and characterization of its temperature sensitivity. Plant Health-2024, Memphis, TN. July 26-30, 2024. 5. K.-S. Ling, J. Zhou, N. Jaiswal, B. Zia, B. Chanda, A. Gilliard, J. McGuire, A. Shi, J. Tung, S. P. Dinesh-Kumar, S. A. Whitham, and B. Baker. 2024. Managing tomato brown rugose fruit virus in tomato by incorporating short-term disinfection and long-term disease resistance. 7th International Symposium on Tomato Diseases. Brasilia, Brazil. October 1-4, 2024. 6. K.-S. Ling. 2024. Managing the emerging tomato brown rugose fruit virus using ozone treatment and disease resistance. 2024 Canadian Greenhouse Conference. Niagara Falls, Ontario, Canada. October 9-10, 2024.
  • Type: Journal Articles Status: Published Year Published: 2024 Citation: 1. Zhou, J.; Gilliard, A.; Ling, K.-S. Tomato Brown Rugose Fruit Virus Is Transmissible through a Greenhouse Hydroponic System but May Be Inactivated by Cold Plasma Ozone Treatment. Horticulturae 2024, 10, 416. https://doi.org/10.3390/horticulturae10040416 2. Jaiswal, N., B. Chanda, A. Gilliard, A. Shi, and K. Ling*. 2024. Evaluation of tomato germplasm against tomato brown rugose fruit virus and identification of resistance in Solanum pimpinellifolium. Plants 2024, 13(5), 581; https://doi.org/10.3390/plants13050581; https://www.mdpi.com/2223-7747/13/5/581
  • Type: Conference Papers and Presentations Status: Published Year Published: 2023 Citation: 1. K.-S. Ling, N. Jaiswal, B. Zia, B. Chanda, A. Gilliard, A. Shi. 2023. Global emergence of ToBRFV and identification of a QTL associated with resistance in Solanum Pimpinellifolium. 12th ICPP, Lyon, France, August 20-26, 2023. 2. K.-S. Ling, J. Zhou, N. Jaiswal, B. Chanda, B. Zia, A. Gilliard, and A. Shi. 2023. Integrative management of the emerging tomato brown rugose fruit virus in greenhouse tomato production. 37th Tomato Disease Workshop, November 1, 2023, Purdue University.