Promising development in fight against disease
Researchers in Belgium have succeeded in modifying multiple genes that predispose potato plants to potato late blight disease, or Phytophthora infestans. Further testing is being conducted to determine if the new potato plants are resistant to the disease.
However, the EU’s stringent legislation around GMOs could prevent the new plants from reaching the field trial or marketing stage.
Ania Lukasiewicz used CRISPR-Cas technology, a genome editing technique that uses a bacterial immune defense system to alter an organism’s DNA, to modify the genes in her doctoral research at Flanders Research Institute for Agriculture, Fisheries and Food (ILVO). Her new role as a policy researcher at Wageningen UR in the Netherlands has brought her closer to the regulatory challenges posed by the use of gene-edited crops in the EU.
Potato late blight: a troubling pest
Potato late blight, caused by Phytophthora infestans, has long been a scourge on potato production. It was the cause of the great famine in Ireland in the mid-19th century. In the Belgian region of Flanders where most of the country’s potatoes are grown, it still causes major losses. Total annual losses in Europe to potato late blight disease are estimated at around $1.08 billion.
To combat the disease, potato crops are treated with pesticides.
“In the Netherlands, most of the pesticides used are to combat this disease,” Lukasiewicz said. The risk of regular, preventive treatment is the possible formation of resistant variants. For this reason, researchers continue to look for alternative solutions, including breeding potato varieties resistant to late blight.
Breakthrough discovery
Traditional breeding crosses mother and father plants with desirable characteristics. Through a selection of crosses, it is hoped that those characteristics recur in order to confer the desired genetic strengths.
Breeders use resistance genes from wild potato varieties, crossing them with existing commercial varieties, to obtain stable resistance that lasts in the field — a process that can take as long as 50 years.
To accelerate this process, many breeders today use new breeding techniques (NBTs) such as CRISPR-Cas to target and remove disease susceptibility genes, which are used by Phytophthora infestans to infect the plant, multiplying and then spreading.
In her ILVO research, Lukasiewicz succeeded in mutating several genes simultaneously in one pass. A similar process had been used by other scientists that enabled only a single susceptibility gene.
Lukasiewicz’s work is the first to mutate several genes in a single pass. Knocking out several genes in a single blow could radically boost the plant’s defense mechanisms, or even prevent infestation altogether.
“In my research, I took advantage of the high similarity between susceptibility genes in different plant species,” Lukasiewicz said. “We were able to identify a total of 87 genes in the potato genome that we strongly suspect to be susceptibility genes. Within this set of genes, we then made a selection and several of these we were able to successfully modify using the CRISPR-Cas technique.”
Since Lukasiewicz defended her thesis in November 2023, Tom Eeckhaut, a plant science researcher at ILVO and one of Lukasiewicz’s PhD supervisors, has continued the work.
“The gene-edited plants are still being tested and trials are planned,” Lukasiewicz said. “I am pretty excited about this, but it is very preliminary still.”
Whether the “turned off” genes convey resistance in new potato plants remains to be seen.
New legislation slow to finalize
In February, European Parliament voted to ease regulation of gene-edited crops by excluding plants developed using NBTs, such as CRISPR-Cas, from Europe’s strict GMO legislation.
The move was hailed as a victory for biotechnology, but debate over patents and labeling still remains, and the bill has yet to be submitted for vote by member states in the European Council. In the meantime, plants developed using NBTs still fall under GMO legislation.
At the Member State level, obtaining permission to advance studies to the field trial level has been challenging.
Following the successful defense of her thesis, Lukasiewicz decided to pursue a policy work internship at the European Commission. She now works as a policy researcher focused on the regulation of gene-edited crops at Wageningen UR in the Netherlands.
Lukasiewicz said while the European Parliament’s vote is a step in the right direction, delays are expected. Hungary currently serves as president of the Council of the European Union and is not in favor of the proposal. Movement on the topic has stalled as a result.
“The expectation is that nothing is going to be done this year,” Lukasiewicz said.
It’s unclear how long it will take to finalize legislation, but industry stakeholders have expressed confidence that Poland, which will lead the council next year, will make its signing a priority.
What is clear is that access to new late blight-resistant varieties would be beneficial to European potato growers, especially in a year as cold and wet as 2024.
“Phytophthora was quite bad this year, and the harvest of potatoes was devastating,” Lukasiewicz said. “Definitely, looking at disease resistance can make a difference. The goal is to lower the use of pesticides, but also to increase yield and lower the costs for farmers.”
