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First clubroot-resistant canola hybrid registered

When Pioneer Hi-Bred received a registration for its clubroot-resistant canola hybrid in the spring of 2009, the registration provided farmers and researchers with a light at the end of the tunnel, and it was not a train coming either. Rather, the new clubroot-resistant hybrid provides the hope that farmers will be able to continue to grow canola down the road.

Roots of the new Pioneer 45H29 clubroot-resistant hybrid (left) are healthy and unaffected versus roots of a clubroot-susceptible hybrid (right), which exhibit the characteristic galls from clubroot infection.

Pioneer brand 45H29 is the only canola hybrid currently on the market that carries clubroot resistance, and the company was able to get a limited amount of seed out to commercial growers in the spring of 2009. It carries the Roundup Ready trait, and Pioneer Hi-Bred’s research scientist Igor Falak says the canola is not only resistant to clubroot, but has a good agronomic package that does not compromise on yield and includes good blackleg resistance.

Resistance unique to Canada
Falak says that the source of resistance came from Europe. “It was ready-made and verified in Europe, and we went ahead and made crosses to introduce it into our canola germplasm,” he says.

The canola lines then went through greenhouse and field testing with co-operation from the Alberta Research Council’s Ralph Lange. “We had more than one source to begin with, but then we narrowed it down to one source that was doing very well, giving us breeding material to work with,” explains Falak.
 
At that point, Pioneer Hi-Bred worked with the University of Alberta’s Stephen Strelkov to establish which breeding lines had resistance to the Alberta strains or pathotypes of the clubroot pathogen. From there, the most promising lines were field-tested in 2008 in locations where the clubroot strains were known to be present.
 
Strelkov explains that there are a number of different pathotypes of clubroot that have been found in Alberta.  Pathotypes are genetic variations of the pathogen that cause the disease, and resistant varieties may respond differently to the various pathotypes. “The predominant one in central Alberta appears to be pathotype 3, but a total of four pathotypes have been found in the province. They all appear in Alberta, but the pathotype 3 has the highest frequency,” explains Strelkov.
 
In fact, all pathotypes can be found in a single clubroot gall. Strelkov says that usually most of the spores in the gall will be of one pathotype, but the other pathotypes can still be present in smaller percentages.
 
One of the Pioneer Hi-bred test hybrids showed a high level of resistance to the clubroot strains in the field trials. Their new hybrid, 45H29, possesses a high level of resistance to the clubroot pathotype 3. It also appears to be resistant to all other clubroot pathotypes currently identified in Alberta.

Best practices needed to preserve the resistance
“There’s always a danger that with selection pressure, new strains may emerge or some that are rare right now may come to the forefront and become predominant,” explains Strelkov. “Rotation and resistance management will be worthwhile so we don’t lose the source of resistance.”

Ron Howard, a pathologist with Alberta Agriculture at Brooks, says that using resistant varieties is only one tool in the battle against clubroot. “In Europe, where they have had resistant varieties for a number of years, they have found that if these varieties were introduced on to land that was heavily infested with clubroot and grown continuously, it was then two or three years and the resistance had already started to break down,” explains Howard.

Pioneer Hi-Bred, in conjunction with government and university researchers, has developed a set of recommendations to help prevent resistance from breaking down. The cornerstone is to maintain a minimum one-in-four-year crop rotation of canola.
 
Falak says the agronomics of Pioneer 45H29 supports the use of the hybrid across the Prairies, whether clubroot is present or not. He says that preliminary results show a five percent yield advantage of the new hybrid compared to standard “check” hybrids, and that 2009 yield data will help to confirm its agronomics.
 
“We were really happy with the overall agronomic performance, but we are waiting to see, this year, where exactly those numbers are,” says Falak. “Really, though, for the first one out of the gate, it’s a heck of a package.”