At first glance, WW 454 looked like it would be a ho-hum addition to the stable of winter wheat varieties competing for acres on Prairie farms.
Its parents, McClintock and CDC Osprey, were a decent sort, but decidedly average. And the breeder that brought them together 11 years ago was a rookie recruit making his first crosses at Agriculture and Agri-Food Canada’s Lethbridge Research Centre.
Although the line offered a relatively good combination of agronomic attributes and quality, it yields about five per cent less than the standard varieties used for comparisons. That’s usually enough to make it a non-starter in the race to get better varieties into farmers’ hands.
But there was one thing that made WW 454 stand out. For reasons still unknown, it has an uncanny knack for standing up to fusarium head blight, a crippling crop disease that through a combination of reduced yield and quality is estimated to have cost the Canadian grain industry more than a billion dollars over the past three decades.
That’s why WW 454 made history last week.
The Prairie Wheat, Rye and Triticale Recommending Committee voted 56 to three in favour of its registration as a variety, making it the first wheat with a “resistant” ranking for fusarium head blight approved for production in Canada. If all goes well, seed will be in farmers’ hands by the fall of 2014.
“This one was a bit of a surprise,” said Rob Graf, the breeder who made the cross in his first year on the job in Lethbridge. The parental lines, like other winter wheat varieties, are both considered susceptible to the disease. “Based on the cross, we did not expect resistance from this one.
“Obviously there are a number of minor genes that came together to give us this resistance and we’ll be working on trying to figure out just what those genes are,” he said. “It may be a different package of genes than we’ve been looking at in the past.”
Researchers weren’t even screening it for its fusarium resistance until it entered three years of co-op trials, which included trials in which the lines are inoculated with the disease-causing fungus.
Graf said the line had other attributes that prompted him to keep it in his program, although its chances of registration appeared slim at the start.
“It’s got a good winter-hardiness package, it’s got intermediate height. It’s not as short as Falcon although it’s also not as tall as something like CDC Buteo or Radiant. It’s got good strong straw, it’s got good test weight, it has a rust-resistant package as well,” he said.
All in all, it is potentially a good fit for Manitoba conditions, he said.
It even has “a nice bump” in protein, enough that it would qualify for the Canadian Wheat Board’s premium winter wheat program.
But those qualities alone wouldn’t have been enough to keep it.
“Had it not looked good for fusarium head blight, because of that bit of a yield disadvantage, we would have kicked it out,” Graf said, noting the data was consistent over three years.
As well, the quality assessors on the registration committee could have nixed it on the basis that it has an extraordinarily strong gluten, which makes for longer mixing times for processors.
“We’ve never seen numbers at that level in this class of wheat,” said Graham Worden, the Canadian Wheat Board’s senior manager of technical services, who serves on the quality evaluation team. That said, however, “the baking quality was quite good.”
Graf is careful to note that a “resistant” rating is a relative term when dealing with a disease like fusarium.
“Under severe conditions you will still see infection. But this certainly, on the winter wheat side, is a step in the right direction,” he said.
Jeannie Gilbert, an AAFC plant pathologist who serves on the committee’s disease evaluation team, also cautioned more analysis is necessary before the designation is conclusive.
Although the plant itself does not appear to be affected by the disease, Gilbert said it is important to go the next step and assess the wheat kernels for fusarium damage and determine whether the mycotoxin deoxynivalenol (DON) is present in samples.
The correlations between field symptoms of the disease, fusarium-damaged kernels and DON production can vary with different varieties.
However, Gilbert said the data so far looks promising and it bodes well for continued efforts to get improved fusarium resistance into Prairie wheats. “Suddenly the bar has been raised very high,” she said.
Farmers could well find that the yield drag is offset by its higher protein and a reduced need for fungicides.
Although winter wheat can often dodge fusarium because it is past flowering during the peak infection season, the 2010 crop saw winter wheat harder hit by fusarium infections than spring wheats. It underscores the need for improved disease resistance, she said.
Gilbert said the line opens new avenues in the search. This kind of breakthrough has occurred with other diseases in the past. “This isn’t the first time that we’ve seen lines in which there is nothing in the parents to make you believe that they should have resistance,” she noted.
In plant-breeding lingo, the phenomenon is called “transgressive segregation.”
Graf has a more down-to-earth explanation. “Quite frankly, the stars lined up and we got somewhat lucky.” [email protected]
– jeannie gilbert, aafc