Agriculture Canada oat breeders are hoping to beat rust with a pyramid of resistance.
They have discovered that former defences against a disease can be built into a new line of fortifications, even after they have been overwhelmed.
“We’re hoping we can pyramid genes together,” Jennifer Mitchell Fetch said on a recent sunny afternoon as she and her colleagues used small scythes, rubber bands and their hands to harvest early generation lines of oats at Winnipeg’s Cereal Research Centre.
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“We’re trying to get five or six genes into one pyramid,” she said.
Crown and stem rusts can devastate oat crops, as they did two years ago.
Breeders repeatedly develop resistant lines of oats, but eventually each is defeated by the rust diseases, which follow their own natural and aggressive breeding program in farmers’ fields.
With the advent of biotechnology, researchers such as Mitchell Fetch are able to zero in on specific genes that provide the disease resistance and attempt to move it into commercially useful lines of oats.
Instead of genetically modifying the crop, they make much use of genetic identification.
One tough gene that provided farmers with years of resistance to rust was PC 68, which ended up in about 85 percent of Manitoba oat crops. Unfortunately, rust overwhelmed PC 68 about six years ago.
Since then, researchers have developed varieties with other resistant genes, such as Leggett that contains crown rust resistant PC 94 and Stainless that contains crown and stem rust resistant PC 91.
However, they aren’t satisfied with just finding new magic bullets to replace PC 68, realizing these individual genes will offer only short-term resistance until the disease evolves, leaving farmers and breeders on a treadmill of innovation to keep slightly ahead of rust.
Instead, researchers want to combine these genes so the disease has a tougher job of adapting to the resistance.
Not only do the researchers want to combine the newly recognized resistant genes, but they also want to resurrect ones that seem anachronistic by themselves but seem to still work if they have partners.
For example, Summit contains two defeated genes – PC 68 and PC 48 – but is resistant to rust.
“For some reason, and it’s something (fellow researcher) James Chong and I have wondered about, Summit is resistant to crown rust,” Mitchell Fetch said.
“If we can keep defeated genes in the lineup, maybe we’ll get more resistance.”
They hope to pile up genes PC 97, 94, 91, 68 and 48 in oat varieties.
“Resistance for five, 10, 20 years would be great,” she said.
“They might be able to overcome one gene, but not all of them at the same time.”
