Scientists are searching wild potato species for resistance to blackleg in the first phase of a new study at the Agriculture Canada Lethbridge Research Centre. The disease-causing bacteria induces about $32 million in damage to potato crops in Alberta each year.
The four-year project aims to identify new sources of genetic resistance and incorporate them into new potato varieties, said researcher Debbie Fujimoto. Since domestic varieties come from few sources, wild potatoes offer more genetic diversity.
Most of the wild species selected for screening are from the United States Department of Agriculture in Wisconsin, which has the largest collection in North America, said Fujimoto, a molecular bacteriologist. Successful material from previous research by the centre’s Dermot Lynch and other scientists will also be screened.
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Blackleg is a seed-borne disease that produces blackened stems and stunted, wilted plants in the field. Infected seed either fails to germinate, or produces an infected plant that can spread disease to other plants. The bacteria causes soft rot in stored potatoes and makes them unusable for processing.
The only control measure is sanitation to prevent spreading after the disease occurs – cleaning up debris from infected material and using disease-free seed, said Fujimoto. Genetic resistance offers the best potential for prevention.
After the selection phase, researchers will cross resistant cultivars with susceptible ones to determine the inheritance of resistant genes, she said. They will then develop molecular markers so the genes can be easily tracked in a breeding program.
Molecular markers are identifiable DNA fragments on a chromosome that are consistently linked to the desired trait, in this case blackleg resistance, that scientists are looking for. When molecular markers are known, breeders can look for the marker that indicates the presence of the resistant gene in a plant, eliminating years of extra testing.
Once in the breeding program, resistant genes can either be bred through traditional methods into new cultivars or incorporated by inserting the genes into existing varieties in a laboratory, said Fujimoto.
New blackleg-resistant cultivars can be quickly transferred to the industry through the potato program’s Western Potato Consortia.
