For further information
Media Relations
Agriculture and Agri-Food Canada
1-866-345-7972
aafc.mediarelations-relationsmedias.aac@agr.gc.ca
For most people, a wart on their skin is an unsightly nuisance, but generally a minor problem. For farmers, potato wart disease found on a tuber poses a much more serious threat. Potato wart is caused by a soil-borne fungus, Synchytrium endobioticum, whose spores can remain dormant in a field for more than 40 years and causes cauliflower-like formations and warty growths on potatoes. Although potato wart poses no threat to human health or food safety, there are no known treatments that are effective against potato wart, and it could have huge financial impacts for growers by making potatoes unmarketable and limiting the use of the affected fields in the future.
When potato wart was detected on Prince Edward Island, it resulted in major impacts on potato production and exports. While steps have been taken by the Canadian Food Inspection Agency (CFIA) and potato growers to help contain, control, and prevent the movement of potato wart within the province and beyond, Agriculture and Agri-Food Canada (AAFC) and CFIA researchers across Eastern Canada have also been researching this complex disease to provide farmers with additional options to reduce its effects.
Do genes hold the key?
AAFC research scientist Dr. Hai Nguyen at the Ottawa Research and Development Centre has been studying the potato wart genome (its full set of genes) over the past several years.
“As we sequence the potato wart genome, it gives us a base to better understand what is causing the infection in potatoes, what metabolic pathways it uses to survive, and what its weak spots might be. Once we know what the sequences look like, we can develop better detection tools, and we might have a better chance to design different treatments to block or interfere with critical pathways and effectively block its infection in potatoes.”
- Dr. Hai Nguyen, research scientist, Agriculture and Agri-Food Canada
Dr. Nguyen joined forces with scientists in the Netherlands, where producers also battle potato wart. By 2022, the collaborators were able to map out several genome sequences for potato wart. This mapping is opening doors for further AAFC research in the fight against potato wart, making Canada one of the leaders in potato wart genomics research.
Dr. Nguyen’s research is helping develop new tools to detect the different types of potato wart. Although potato wart is caused by a single species of fungus, there are more than 40 different types of potato wart across the globe, each identified by their ability to cause disease on different potato varieties. On Prince Edward Island and Newfoundland and Labrador, a total of three types of potato wart have been found.
“Different potato fields throughout the world might have one or a combination of the types of potato wart. Finding every gene in each type will greatly improve our ability to detect if potato wart is present in the soil and what type is found in that specific field,” explains Dr. Nguyen.
Genomics evolve over time, and while Dr. Nguyen and his team have been able to identify the genome of one type of potato wart, further research is being done to improve the quality of this genome, as well as identify the genes for the three types of potato wart known to occur in Canada.
“We are working towards creating what I call the ‘pan-genome’. It would be a single genome that represents all different types of potato wart,” says Dr. Nguyen.
"The ‘pan-genome’ combines all of that diversity. It will help in the development of more efficient potato wart detection tools and in the breeding process for new potato wart resistant varieties.”
Fighting potato wart with potato varieties
Potato wart is extremely persistent, and currently, the only effective way to control the disease is to prevent the movement of soil from one location to another. AAFC scientist Dr. David De Koeyer and his team with the AAFC National Potato Breeding Program, located at the Fredericton Research and Development Centre, are hoping to prevent potato wart at the source - the potato, or specifically by developing potato varieties resistant to potato wart.
“Resistant potato varieties are critical in the battle against potato wart. While there aren’t any known ways to eliminate the pathogen just yet, what we can say is that with a highly resistant variety, the population of a pathogen is not going to increase, and it will provide protection against further spread.”
– Dr. David De Koeyer, research scientist, Agriculture and Agri-Food Canada
The team in Fredericton isolated DNA and screened the hundreds of potato varieties and breeding clones in their inventory with the DNA markers associated with resistance to potato wart.
“We have identified some resistant varieties for fresh potato producers, including russet and red potato varieties, but we haven’t yet found a strong French fry or potato chip processing variety with the same resistance potential. That’s where we are focusing our breeding efforts with support from the PEI Potato Board,” explains Dr. De Koeyer.
Breeding plants is very labour-intensive and Dr. Nguyen’s gene identification research will speed up Dr. De Koeyer’s breeding research by identifying the genes that cause the disease in each potato wart type. This will allow the breeding program team to use resistant gene markers to eliminate potato varieties that are easy targets for potato wart, find potato varieties that might already be resistant to potato wart, and develop new potato wart-resistant varieties.
“We have a lot of historical data, and we have a lot of germplasm (potato plant material), that's resistant. Now we must find the relationship between the DNA markers and their reactions to specific potato wart types. The predictability of the markers for resistance is still a work in progress,” says Dr. De Koeyer.
Newfoundland and Labrador’s world-leading research site
About 67 kilometres west of St. John’s, Newfoundland and Labrador, is the AAFC Avondale Research Farm that is ideal for researching potato wart. The fungus was first discovered in Newfoundland in 1909, and since then, any soil, potatoes or other root crops grown there cannot leave the island in order to prevent the spread to other regions. The presence of potato wart and quarantine status of Newfoundland and Labrador make the Avondale site a unique and highly valuable research site. It is the only outdoor field site in the world where potato wart research can be conducted in a farm environment with the disease present in the soil representing various populations of the pathogen found throughout the province. Following the 2021 detections of potato wart on Prince Edward Island, AAFC ramped up its efforts to modernize the Avondale site. New gates, fencing, and access to water were installed, and the full field area was maximized for research trials.
AAFC St. John’s researchers Dr. Linda Jewell and Dr. Tobias Laengle, joined by newly hired biologist Dr. Mohsin Zaidi, and dedicated research technician Karen Compton, are supporting the research efforts at the Avondale site. They are testing potentially resistant potato varieties from Dr. De Koeyer, as well as new fungicides and biological control products to see if they might be able to control potato wart.
The research on potato wart continues to be a collaborative effort as everyone connects key pieces to the puzzle.
“The process will take time, but with a great team working together on several different tools and methods to speed up our research processes, and with new advancements in genomics research and breeding, we are moving closer to our end goal of finding a way to manage potato wart.”
- Dr. Linda Jewell, research scientist, Agriculture and Agri-Food Canada
Key discoveries/benefits
- A team of AAFC scientists throughout Eastern Canada are working to research this complex disease and provide farmers with options to address potato wart, a soil-borne fungus that can remain dormant in a field for more than 40 years and causes cauliflower-like formations and warty growths on potatoes.
- Although potato wart poses no threat to human health or food safety, it can have a huge impact on potato growers by making potatoes unmarketable and limiting the use of affected fields in the future.
- AAFC research scientist Dr. Hai Nguyen at the Ottawa Research and Development Centre has been studying the potato wart genome (its full set of genes) over the past several years.
- Dr. Nguyen’s research is helping in the development of new tools to detect the various types of potato wart. Genomics evolves over time, and while Dr. Nguyen and his team have been able to identify the genome for one type, further research is being done to improve the quality of this genome, as well as identify the genes for the three types of potato wart known to occur in Canada.
- Dr. David De Koeyer and his team with the AAFC National Potato Breeding Program, located at the Fredericton Research and Development Centre, are hoping to help prevent potato wart at the source - by developing potato varieties that are resistant to potato wart.
- Dr. Nguyen’s gene identification research will help speed up Dr. De Koeyer’s breeding research by narrowing down the genes in each potato wart type. This will allow them to identify resistant gene markers to eliminate potato varieties that are more likely to be infected with potato wart, find more potato varieties that might already be resistant to potato wart, and develop new potato wart resistant varieties.
- West of St. John’s, Newfoundland and Labrador, is the AAFC Avondale Research Farm, the only dedicated outdoor field site in the world where potato wart research can be conducted in a farm environment.
- AAFC recently ramped up its efforts to modernize the Avondale site. New gates, fencing, and water access were installed along with clearing the full field area to maximize space for research trials.
- AAFC St. John’s researchers Dr. Linda Jewell and Dr. Tobias Laengle, joined by newly hired biologist Dr. Mohsin Zaidi, support the research efforts in Avondale to test potentially resistant potato varieties from Dr. De Koeyer and different control strategies for potato wart.
Dr. Linda Jewell showcases potato samples to Netherlands-based scientist Dr. Theo van der Lee at the AAFC Avondale Research Farm.
Dr. David De Koeyer shows off two of dozens of potato varieties that he and his breeding team are testing for resistance to potato wart.
Dr. Hai Nguyen’s discoveries in genomics research on potato wart support the identification of resistant varieties, detection tools, and the potential development of potato varieties resistant to potato wart.