University of Saskatchewan

April 17, 2014   

Genes key to rust resistance in wheat

Kirby Nilsen, a University of Saskatchewan plant science graduate student, is researching rust-resistant wheat genes (David Stobbe photo).
October 05, 2012

By Lisa Buchanan

Saskatchewan plant scientists are working to stay one step ahead of a fungal disease — stripe rust — that they fear may be moving into the province and starting to reduce wheat crop yields.

Rust is a fungal disease which occurs wherever wheat is grown around the world. It robs plants of their nutrients, reduces yield and lowers grain quality. Severe infection can kill an entire plant.

Stripe rust typically prefers cool, moist weather. But now researchers fear it may be adapting to warmer, drier areas, partly due to weather changes.

“Particularly in western Saskatchewan, which is usually hot and dry, recent summers have been hot and humid, resulting in more leaf diseases in cereals and other crops,” said Grant McLean, cropping management specialist at Saskatchewan Agriculture.

While leaf rust is common on the prairies, stripe rust, which appears as yellow stripes on leaf blades, usually blows in from the Pacific Northwest in mid- to late summer, infecting Canadian crops later in the season.

Last year, Alberta experienced what some have called a stripe rust epidemic. Plant pathologists suspect the rust overwintered on wheat in Alberta and Saskatchewan, allowing it to move to spring wheat earlier and cause more damage than usual.

“If stripe rust becomes more widespread, the damage could be quite severe because we don’t know as much about it,” said University of Saskatchewan plant science graduate student Kirby Nilsen.

“We want to know what resistance we have in our breeding lines so if there is ever a full-blown epidemic, we’ll be one step ahead.”

Research shows Lethbridge, Alta., experienced a wheat yield reduction of up to 75 per cent in 2011. Economic losses due to stripe rust on the prairies are difficult to calculate at this stage, but losses in the central U.S. were estimated to be $267-million in 2003.

With funding from the Canadian Wheat Board, Nilsen is looking for wheat genes that provide resistance to both leaf and stripe rust. While plant breeders already breed for disease resistance, he is looking to identify genes that provide long-term, durable genetic resistance to both forms of the disease.

“We feel that breeding for disease resistance is the most effective approach to limit the spread of wheat rust,” Nilsen said.

Nilsen’s supervisor Curtis Pozniak, a Canadian leader in molecular genetics and breeding of wheat, says Nilsen has identified a promising gene in Canadian wheat that provides effective resistance to both leaf and stripe rust.

“He is well on track to develop diagnostic DNA markers to track that resistance in breeding programs so it can be maintained in newly developed cultivars,” said Pozniak, who co-leads an international research team mapping the genome of the best Canadian wheat varieties with an $8.5-million grant from Genome Canada, the Western Grains Research Foundation, the Saskatchewan government, and other partners. “Disease resistance is a top priority for breeders locally and globally,” he said.

The genes Nilsen is looking for don’t provide resistance until the plants are approaching flowering. That’s when yield development is most crucial. It takes longer for pathogens to adapt to this type of resistance, making these genes more durable than others to which diseases are able to adapt rather quickly — sometimes within a few years.

His discoveries will potentially have commercial impact. Disease resistance reduces crop losses and lowers the need for fungicides, putting more money in producers’ pockets.

“As diseases adapt, the number of effective resistance genes diminishes, so working to identify new ones is of great value to plant breeding programs worldwide,” Nilsen said.

His cutting-edge research will serve him well as he embarks on a career in plant breeding.

“It’s something I really enjoy doing,” he said.

Lisa Buchanan is a graduate student intern in the U of S Office of Research Communications.

This article first ran as part of the 2012 Young Innovators series, an initiative of the U of S Research Communications office in partnership with the Saskatoon StarPhoenix.

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