Wheat midge tolerant gene at risk

A gene that has been found in the wrong place could potentially be putting part of the prairie wheat sector at risk.

SeCan, a farmer-owned seed distribution company, has learned that soft white wheat varieties in Western Canada, in particular AC Sadash, inadvertently contain a gene known as Sm1.

Sm1 is the wheat gene that confers tolerance to the orange blossom wheat midge.

To protect the efficacy of the gene, all wheat varieties that contain the trait are blended with a refuge variety that is susceptible to midge damage.

The presence of a refuge variety reduces the chance of insects developing resistance to the Sm1 trait.

“The fact that we have been growing SWS without a (midge susceptible refuge variety) puts the Sm1 trait at risk,” SeCan said in an April 5 news release.

“Midge tolerant wheat saves producers $40 to $60 million per year, (and) there are no replacement tolerance genes. For this reason, we need to act as quickly as possible to put a stewardship plan in place for the benefit of all wheat producers.”

Todd Hyra, SeCan’s business manager for Western Canada, said the discovery of the Sm1 gene in Sadash and other SWS varieties came as a surprise to the company and plant breeders who develop soft white wheat varieties.

Wheat breeders did not intentionally insert the gene into new SWS varieties that they developed.

Nonetheless, the discovery of the gene in Sadash prompted SeCan to take immediate and extraordinary steps aimed at managing the midge tolerant Sm1 gene and ensuring that is adequately protected.

The company has asked all pedigreed seed growers and commercial grain farmers who have AC Sadash in their bins and plan to either plant it or sell it as pedigreed seed to blend Sadash with quantities of AC Andrew, another SWS variety.

“We need to rely on everyone to be willing to work with us, and generally the membership (of SeCan) has been supportive,” Hyra said. “They understand the implications, they understand there are some timelines, but they also understand the need for stewardship.”

The co-operation of commercial grain farmers who use Sadash and have been planting it as farm-saved seed is another question.

Hyra said SeCan considered deregistering Sadash to ensure the Sm1 gene is not compromised.

Eventually, the company decided to seek the co-operation of SWS growers.

Sadash is currently the most widely grown soft white variety in Western Canada.

It has been distributed commercially in Western Canada for the past seven years, and in 2016 the variety was planted on hundreds of thousands of acres across the West.

“Sadash is out there, so we’re going to have to rely on the goodwill and co-operation of farmers,” Hyra said.

“Another part of this is making sure that we have adequate supplies of AC Andrew to meet the (blending) needs of the industry.”

Hyra said it could take a couple of years to ensure that adequate stocks of AC Andrew are available.

Seed growers who have AC Andrew in storage will be asked to plant as much as possible this year.

AC Sadash and AC Andrew should be blended at a ratio of 9:1.

Hyra said commercial grain growers who co-operate with SeCan’s blending request will be expected to source, supply and blend AC Andrew at their own cost.

Further down the road, they may also be asked to renew supplies of Sadash seed every two years, in conformance with existing midge tolerant stewardship agreements.

If the industry-wide appeal to blend Sadash does not produce the intended results, deregistration of Sadash is still an option that may be considered, Hyra added.

The Sm1 gene is not new to seed breeders or to the pedigreed seed industry, but its discovery in AC Sadash and other SWS cultivars came out of the blue.

Over the past decade or so, the gene was knowingly incorporated into more than 20 varieties of wheat in the CWRS, CPSR, CWES, CWAD and CWGP classes.

It is still unclear how many SWS varieties contain the gene, but SeCan officials confirmed that three varieties in their portfolio — AC Sadash, AAC Indus and AAC Awesome — are among the SWS varieties that unexpectedly carry the trait.

A fourth SeCan variety — AAC Paramount — is also believed to contain the trait, but further testing is required to confirm that, said Hyra.

Awesome, Indus and Paramount are relatively new varieties so they have not been distributed widely to commercial grain growers.

As a result, it should be relatively easy to ensure that a refuge variety is added before widespread commercial release.

But for Sadash, the addition of a refuge variety will be a huge undertaking.

“The big piece of this that will require the assistance of producers is the adding of a refuge to the farm-saved supplies of Sadash that are out there,” Hyra said.

“That’s a … path that we’ve never gone down before so it will … require their participation to make sure that the midge tolerant gene is protected.”

Hyra said there is no evidence to suggest that the commercial production of Sadash without a refuge over the past six years has compromised the efficacy of the Sm1 gene.

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