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The next frontier of plant breeding

Advocates say game-changing genome editing is completely different from genetic engineering — but will the public agree?

Farmers need to get in front of the messaging about genome editing technology — or risk seeing it suffer the same fate as GMOs in the court of public opinion.

That’s the warning from the chair of Alberta Wheat’s research committee, who is one of many who fears genome editing is going to get lumped in with genetic modification in the minds of the public.

“I think part of the problem with the current resistance to GMOs is because it was not well publicized. It was a disgrace actually,” said Lacombe-area producer Terry Young. “The technology came out and 10 years later, the public found out what it was being used for and then they were all up in arms because they didn’t have awareness of or input into the process.

“We need to set the record straight and do so in a more timely fashion.”

Genome editing is fundamentally different from genetic engineering. Unlike the latter, the process doesn’t involve inserting a gene from another species. Instead, a very small part of a plant’s DNA is removed or modified. The technique is so precise, scientists compare it to changing a bit of text in a document — hence the term editing.

For plant breeders, one use of this technology — sometimes called ‘gene silencing’ — is particularly promising. In traditional breeding, scientists take a plant with a desirable trait (such as resistance to a particular disease) and cross it with a commercial variety. However, it’s not just that one gene that shows up in the offspring, but a bunch of them. Invariably, some have negative impacts (frequently that includes reduced yield). So the old-fashioned way is to make lots of backcrosses with the high-yielding commercial parent in hopes of eventually getting one that has both the sought-after new trait and all of the attributes of the commercial variety. Typically several backcrosses are needed — which takes time, costs money, and is hit and miss.

But if you can identify the genes in the first cross that are causing a problem (such as suppressing yield) and then edit (or silence) them so they are not fully expressed, you can — in theory — go from start to finish in one step. Alternatively, a desired genetic trait could be transferred directly from one variety (of the same crop species) to another.

That’s a big difference from a scientific point of view, but whether the public will see it that way is still up in the air. And the battle lines have been drawn for some time.

Genome editing is GMOs because the technology still changes the fundamental makeup of plant material, Brise Tencer of the Organic Farming Research Foundation told the New York Times three years ago.

“They take a term (genome editing) that sounds really wonderful, but genetic engineering is genetic engineering,” Tencer said.

One of the first crop varieties developed with genome editing is a waxy corn cultivar that has high levels of a type of starch (amylopectin) used for both food and industrial products. This graphic was created by DuPont Pioneer to show how genome editing — and not genes from another species — was used to create that cultivar. In this case, researchers deleted part of a gene in elite hybrids that restricted amylopectin starch production to produce a high-yielding variety with high levels of this type of starch. This gene edited variety, now in field trials, will be grown for a niche market when it is released in the next year or two. Only about half a million acres of waxy corn are grown annually. — Staff
photo: File

In February, genome editing took a bit of a public relations hit when U.S.-based plant-breeding company Cibus released SU Canola, a variety developed with genome editing technology, in Canada. At the same time the company announced its support of the #NonGMO project. Some saw the move as a kick in the teeth to farmers growing genetically modified crops and took to Twitter to express their dismay.

However, Young is optimistic consumers will support the technology if there is sufficient education and awareness.

“Those who are familiar with it think it’s going to be a benefit, but those who aren’t too familiar with gene editing are unaware of its potential,” he said. “My thinking is if everyone was educated about the technology it would be very positive, because it allows a much cheaper alternative to modifying the plant than even genetic modification.”

Precision surgery

The two most prevalent genome editing technologies are Clustered Regularly Interspaced Short Palindromic Repeats (CRISPR) and Cibus’ proprietary Rapid Trait Development System (RTDS), which the company used to develop its sulfonylurea-resistant SU Canola. Both target removal of undesirable traits in plants and animals.

“For me, genome editing is like surgery. It’s really, really precise. We have to know what we’re targeting before we do it,” said Stacy Singer, a researcher with Agriculture and Agri-Food Canada’s Lethbridge Research and Development Centre. “It has potential to be a lot faster than conventional breeding methods. It’s really different from anything that has been used for breeding purposes before.”

And the end results are “pretty much identical to what you would get with a conventional breeding method,” she added.

“With conventional breeding, however, you get a whole bunch of other changes and you don’t know where in the genome any of those changes have happened because it’s all random.”

The CRISPR process involves a specific protein called Cas9 — which has been likened to a set of genetic scissors that essentially ‘cuts’ the DNA — and a single guide RNA which takes the Cas9 to the chosen DNA location. The result is a very small change in the DNA.

“Once you’ve got that change, the Cas9 protein and single guide RNA are either simply degraded in the plant cell or removed, so you’re only left with the edit,” said Singer. “It’s pretty much an immune system from a bacteria that has been harnessed and changed to elicit genome editing.” Cibus’ RTDS system is more complicated, but ultimately results in the same precise targeting of DNA.

“The sky’s the limit really,” said Singer. “What genome editing can do depends on what growers and industry are looking for, what they’re having trouble with in that moment, or if they foresee a problem in the future. Those are the sort of things we’re hoping to target.”

Targeting the potential effects of climate change with genome editing is a priority at Singer’s lab (and many others).

“We would like to make forage crops more resilient to things like drought or salt, for example,” she said. “But there are all kinds of things we could potentially improve in forage crops, such as reducing the risk of bloat in livestock from the forages that they eat.

“It’s not necessarily that we will be able to do everything using genome editing, but I think it will kind of open doors for us and speed things up.”

Crop producers would like to see a host of improvements, said Young.

“There are possibilities in targeting photosynthetic efficiencies, reducing reliance on inputs, making crops more drought tolerant, and nitrogen and water use more efficient,” he said.

Gaining acceptance

The second item on Young’s list — reduced inputs — illustrates another facet of the ‘genome editing is different’ discussion.

Singer said she is worried that the development of genome edited applications will go down the path that produced GMOs — a business model focused on whichever products make the most money. She said she would rather see participants throughout the ag value chain have a say in how the technology can best serve their businesses.

“With GM, for example, the regulatory process is so expensive that it has been limited to large corporations,” said Singer. “On the one hand that’s fine, but the traits that get improved tend to be the things that will make money because that’s how corporations work.

“We really need to work towards finding a way for everyone to be working on this so we can get some things out there that are beneficial to people that they would really like or really want.”

Young expects most farmers will welcome new crop varieties created with the new technology.

“I think you’re going to find various producers on side with all kinds of pros and cons of a certain technology,” he said. “But typically it’s only a couple per cent that are really hardcore against it. Then you see a group in the middle that needs more information. Then you see people on the other side who are hardcore for it.

“I would say — and this is my opinion — that more producers will definitely be for it.”

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