Texas A&M AgriLife Research aims for better control of widespread tomato spotted wilt virus
Federal grants to help wrangle vector-borne disease of tomatoes, peppers, thousands of other plants
Texas A&M AgriLife Research scientists have received two grants from the U.S. Department of Agriculture and the National Science Foundation to develop better control and understanding of tomato spotted wilt virus, one of the top 10 most economically important plant viruses in the world.
Kiran Gadhave, Ph.D., AgriLife Research scientist and assistant professor in the Texas A&M College of Agriculture and Life Sciences Department of Entomology, Amarillo, will lead one grant and is a co-investigator on the other.
The most recent project and the one Gadhave is leading is funded by a three-year, $887,000 grant from the USDA Agricultural Marketing Service, USDA-AMS, will pursue research applications to develop better control of the pathogen.
A related three-year, $993,002 grant from the National Science Foundation and the USDA National Institute of Food and Agriculture will focus on understanding the virus on a fundamental level.
“We are tackling this problem from multiple perspectives, bringing in interdisciplinary expertise from different institutions,” Gadhave said.
Knowns and unknowns about the versatile virus
Tomato spotted wilt virus infects more than 1,000 plant species, including both specialty and staple food crops and weeds, causing an estimated $1 billion in crop losses worldwide each year.
Stunting, mosaic-like patterns on leaves, a lack of fruit, or rot-like spots on fruit are some of the symptoms of the disease in crops. Badly infected produce cannot be sold and is unpalatable.
Studies show the virus continues to change, and new strains have been reported in at least 10 countries.
“A single gene in tomatoes offers resistance against this virus,” Gadhave said. “But new virus strains have emerged, which our lab has reported, that have been breaking that resistance. So those virus-resistant tomato cultivars are not completely effective anymore.”
These “resistance-breaking” strains of the virus are of particular concern and will be a key focus of the new applied and basic research.
Another complication in combating the virus is its main insect vector, western flower thrips. This tiny insect is a damaging pest even on its own.
“The unique thing about this virus is that it can replicate in insect and plant hosts,” Gadhave said. “It’s a cross-kingdom virus.”
Yet another tricky thing about tomato spotted wilt virus is that it infects weeds, using them as a “green bridge” to cross into vulnerable crops, Gadhave said. “That’s where the virus stays when there is no crop around, and it’s why surveillance will be an important part of our work.”
Applied research
The applied USDA-AMS project serves many potential beneficiaries. It aims to help vegetable growers through new crop cultivars, new detection methods, and updated, science-based management recommendations. The results and outcomes will also inform future research and education.
In addition, given the global agricultural significance and economic impact of the tomato spotted wilt virus, the project will also help educate the public about agriculture, Gadhave said.
“Our project aims to inform the general public of the challenges that plant viruses and vectors present to global food and nutritional security.”
Joining Gadhave on the USDA-AMS grant are Texas A&M faculty members Xudong Rao, Ph.D., AgriLife Research associate professor, and Xingguo Wang, Ph.D., AgriLife Research assistant professor, both in the Department of Agricultural Economics and stationed in Fort Worth; and Kevin Crosby, Ph.D., AgriLife Research vegetable breeder and professor, Department of Horticultural Sciences, Bryan-College Station.
Other collaborators include Anna Whitfield, Ph.D., and Dorith Rotenberg, Ph.D., both professors at North Carolina State University in Raleigh; and Tomas Melgarejo, Ph.D., assistant project scientist at the University of California, Davis.
To tackle the formidable agricultural threat, the team on the USDA-AMS project will pursue six connected goals:
- Surveillance of resistance-breaking virus strains in major tomato and pepper growing regions of the U.S.
- With growers, estimate the economic losses due to the virus and calculate the cost-effectiveness of different management strategies.
- Development of diagnostic tools to reliably and efficiently detect resistance-breaking virus variants.
- Understanding the transmission biology of the resistance-breaking strains and identifying strategies to disrupt transmission.
- Evaluating the impact of growing practices on disease transmission, including a comparison between high tunnels and open fields.
- Developing new crop cultivars with strong resistance to resistance-breaking virus strains.
Fundamental research
Gadhave is also the co-principal investigator on the joint grant from the National Science Foundation and the USDA National Institute of Food and Agriculture. Funded through the NSF–NIFA Plant Biotic Interactions Program, this project will investigate how the resistance-breaking strains of the virus interact with the tomato at the molecular level.
While the USDA-AMS project will focus on applied science, the NSF-NIFA project’s scope is fundamental research. The principal investigator on that project is Hanu Pappu, Ph.D., Carl F. and James J. Chuey Endowed Chair and President Sam Smith Distinguished Professor in Plant Virology at Washington State University, Pullman.
“We want to understand how the new strains of the virus overcome the genetic resistance of the host and how tomato plants respond/defend during infection and disease progression,” Gadhave said.
What’s next
After the USDA-AMS work is completed, Gadhave said, growers should have a new, cutting-edge diagnostic tool, research-based recommendations for sustainable crop production, and, potentially, new cultivars.
The most recent economic estimates on the disease’s impact were made in the 1990s, and these will be updated to guide growers’ management decisions, hopefully translating into higher economic returns.
Both the applied and basic research projects will benefit the scientific community by contributing to national and global efforts toward controlling both the tomato spotted wilt virus and thrips.
As an additional benefit, Gadhave aims to use the outcomes to educate the public about sustainable agricultural practices.
“We’ll make significant progress collectively in all these areas,” Gadhave said. “This is the beauty of these projects.”
In the long-term, new findings about how the virus infects plants and insects will inform research on disrupting viral transmission. For example, weeds that serve as reservoirs of the virus and alternate hosts of thrips can be identified and removed.
Gadhave also sees future questions arising from this research.
“This virus will keep evolving,” Gadhave said. “And we will continue our efforts to find new, sustainable ways to reduce its economic impact on global agriculture.”
