Potatoes in Canada

Features Agronomy Crop Protection
Controlling beetles with lunch

Researchers know that the Colorado Potato Beetle ignores many of its wild relatives, and are determining which species could be bred with potatoes to deter  the pest. Photo courtesy of Ian MacRae, University of Minnesota.

Keeping the pesky Colorado Potato Beetle (CPB) under control is a full-time job for growers. With bugs developing resistance to pesticides a constant worry, researchers are looking for alternative ways to control the bugs. The most sensible idea is to create a plant that beetles don’t want to eat. The potato is a member of one of the largest group of plants on earth and is a relative of eggplant, peppers and, surprisingly, petunia – the pretty flowers we grow in window boxes. However, while CPB munch on the potato plant, they ignore the petunias growing along the fence row.

Scientists who study potatoes know that the CPB does not like many of its wild relatives, so researchers started there to determine which species could be crossed with potatoes to create a plant that is less palatable to CPB. The researchers at the Agriculture and Agri-Food Canada (AAFC) Potato Research Centre in Fredericton determined that metabolites in the plant’s leaves repulsed the beetles. Then, they considered how to get the metabolite into or onto the potato plant. The idea of developing a spray was dismissed as too complex because the product would have to be sun-tolerant, rain resistant and immune to other weather conditions. The spray option was not deemed economical in comparison to commercial pesticide products.

“This work has been ongoing for 15 years,” admits Dr. Yvan Pelletier, who recently retired from AAFC and who worked on the search for metabolites to breed into potatoes that would take the bite out of CPB. “This is a worthwhile endeavour, but it takes time.” He says the team finally determined that the wild potato (Solanum oplocense) is the plant most likely to succeed when it comes to helping domesticated potatoes resist CPB. This wild cousin of the potato can be used with a traditional breeding technique to make the garden variety potato less tasty for CPB.

One of Pelletier’s colleagues, Dr. Helen Tai, has been working to isolate the metabolite and the biochemical pathways that control the metabolite’s production in leaves. She says the process of getting the potato to produce CPB resistance metabolites is done by old-fashioned breeding, which is not too difficult. “We cross-pollinate the potato and wild plant by putting pollen from the wild plant on the emasculated potato plants,” Tai explains. “We chose Solanum oplocense (wild potato) because it has resistance and will cross with potato.” After the cross is completed, she continues, there are some progeny you want and some you don’t. At that point, the team selected the progeny that had the resistance yet still had the ability to develop tubers under northern, long day growing conditions.

“We don’t want to change the potato radically,” comments Pelletier. “We are working on small changes that will make the plant resistant to beetles.”

Tai says determining how to identify and detect the metabolites is part of the process in developing new varieties with CPB resistance. The strategy would involve crossing current favourite varieties with potatoes that have already been crossed with Solanum oplocense so that they carry the CPB resistance, then the resistance metabolite is used to screen the progeny. Using the metabolite will save a lot of time and money in screening for CPB resistance. The research is aimed at getting more potato varieties with CPB resistance to the potato industry and the consumer at a faster rate.

Pelletier says the current progress is being made with beetle resistance in table stock potatoes and he sees a niche opportunity for the organic market.

“There is so much that has to be done in order to ensure the resulting variety is suitable for Canada’s growing conditions,” adds Pelletier. “You have to ensure you get the tuber size wanted, that the maturity of the plants meets our growing needs and that the plants develop properly. We are close to developing our first variety, that would have compatibility with organic growing systems because that market needs products produced without pesticides.”

Meanwhile, Tai continues her work in developing metabolite selection tools for selecting potatoes that the beetles don’t like, which would help the breeders develop varieties for industrial processing. “CPB also develops resistance to pesticides making those products ineffective,” she says. “Our development of CPB resistant potato lines will be a resource that will provide an additional way to avoid CPB-induced crop losses.”

Unsaid by either researcher is how much the development of CPB resistance in potatoes could protect the environment as there would be less and less need for pesticides as more and more varieties would have the metabolite in their makeup.

To make an impact on pesticide use, breeding for CPB resistance alone is not enough. Dr. Tai says that the challenge is getting the CPB resistance in combination with traits in potatoes that are suited to the chipping or frying industries, which make up the majority of the potato utilization in Canada. Without these other traits, breeding for CPB resistance is like going to the moon: we know we can do it, but why bother if we don’t need to go? The development of the metabolite screening tool for breeding is a way forward to more efficient selection of potatoes that are tastier for us and less tasty for the CPB.

October 22, 2014  By Rosalie I. Tennison



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