The secret for complete disease resistance in wheat lies almost entirely within the crop rather than in outside sources, says a crop pathologist on Agriculture Canada’s western Canadian wheat breeding team.
Wheat has all the tools it needs to be disease resistant in its own genome, Lethbridge research centre scientist Denis Gaudet said. All wheat needs is a little “tweaking” to develop new varieties that are better able to fight off disease in farmers’ fields.
“What we’ve seen in the field is that wheat is susceptible to certain insects and certain diseases, but on the other hand, wheat is also resistant to the vast majority of insects and diseases,” he said.
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“We believe wheat has the potential to be resistant to all diseases and pests, with a little help.
“That’s good news for breeders, because it means we don’t have to look to other varieties or species for sources of resistance. It’s good news for wheat producers because it means they can expect to have varieties with improved resistance in their fields, sooner.”
The first step in developing disease-resistant varieties is to identify and understand the genes behind resistance. The challenge is that wheat has a large genome, about five times the size of the human genome, so it’s not easy characterizing all of the genes, or even locating those responsible for disease resistance.
“But it also means there are likely sources of resistance in that genome that we haven’t discovered yet.”
Once those genes are characterized, researchers can incorporate the information into their breeding program.
The main problem with pathogens such as stripe rust and powdery mildew is that the wheat plant doesn’t recognize them as pathogens, Gaudet said.
He believes it is possible to use genetic techniques to “teach” wheat to recognize them as disease threats, and then use the plant’s defence mechanisms to launch an attack.
“That way, we are using the plant’s own genetic machinery to make it resistant, increase wheat yield and quality, and reduce pesticide use, all at the same time.”
This principle could also apply in the battle against snow mould. Gaudet, along with Andre Laroche, another researcher at the Lethbridge research centre, is looking at using defence mechanisms already in winter wheat’s genome for protection against snow mould.
The researchers know that winter wheat has some resistance to snow mould, but is susceptible to the pathogen during the winter.
They are looking at ways to “switch on” the genes to provide protection during the winter.
The researchers believe cold temperature-regulated genes may be one way to improve resistance to snow mould, because the resistance genes could be manipulated to activate automatically when the temperature drops.
