WESTERN PRODUCER — An unexpected side effect of gene editing research at the University of Guelph could pay dividends for canola breeders in the years ahead.
The discovery stemmed from research that began in 2016. The research examined how carbohydrate metabolism is affected in Arabidopsis when substituting one of its genes with the corresponding gene from a corn plant.
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Arabidopsis is a commonly used analogue for canola to test hypotheses. Like canola, arabidopsis is also part of the brassica family, but it has much simpler and easier to work with genetics.
“We didn’t do the initial experiments with the intent of growing a better canola plant,” said Michael Emes from the University of Guelph.
“We accidentally found this remarkable effect when we modified carbohydrate metabolism.”
Emes and his colleague, Ian Tetlow, said the research was just intended to garner insights into carbohydrate biosynthesis. However, while they got some interesting results along those lines, something else stood out — a lot.
“The most obvious things were that the plants were two to three times the size and the yield was up 250 per cent,” he said.
“Now that’s for the model organism (Arabidopsis), not a field crop. It’s basically a weed.”
The plants also showed promising resistance to abiotic (heat and water) stressors.
If researchers could realize similar benefits in canola crops by substituting the same genes, the results would be very interesting to plant breeders.
And that led to the next step in the research. In 2018, a team led by Liping Wang looked at whether those traits could be replicated in canola by adopting the same strategy but using gene editing combined with insertion of the corn gene.
Since canola has already been bred for maximum yield, there was no expectation of yield increases in the 250 per cent range they saw with Arabidopsis. Nevertheless, the results were promising.
While the seed pods and flowers were physically unchanged, the plants produced a lot more flowers and a lot more seed pods. As expected, the yield increases were not as dramatic as they were in the Arabidopsis trials.
“Even so, in greenhouse conditions, yields were increased on average by 30 to 40 per cent, and the thicker stem offered improved resistance to drought and high temperatures,” said Tetlow.
Emes said it’s not well understood why the plants reacted that way, but the plant certainly makes the “decision” to invest more of its energy into reproduction — making flowers and seedpods.
“We domesticate plants because we have a distinct purpose, but the plant has evolved for a different reason,” said Emes.
“It just wants to get to the next generation.”
He said the plants are naturally conservative and often will abort 50 per cent or more of their flowers and pods at early stages in their development to ensure the success of others in producing seeds.
“We think that by adjusting carbohydrate metabolism, the conservative nature of the crop (and of the Arabidopsis) has been overcome,” Emes said.
“I think what’s happened is that the plant calculates that it’s not going to run out of carbohydrates and can afford to make more flowers and pods.”
So, the next step for Emes and his team are field trials. Because there is a transgenic element to these trials — a corn gene is replacing a canola gene —significant precautions are taken when running field trials.
“Once you have a transgene in there, then you have to run what’s called a confined field trial,” Emes said.
“That’s one where there are borders set up to avoid any escapes and to avoid cross-contamination.”
Confined field trials are a lot more expensive than unconfined trials. Fortunately, the abiotic traits that were observed (heat and drought tolerance) can be achieved through gene editing alone, without any transgenes, so field trials that are focused specifically on those traits will not have to be confined.
A 30 to 40 per cent yield increase, combined with heat and drought tolerance, would be traits plant breeders would love to get their hands on, but there’s a long way to go before these discoveries will become available to farmers.
“It’s taken us from 2016 to get to where we are now,” said Emes.
“If all goes well in the current field trials, you’re probably looking at another 10 years before getting this into the hands of growers.”
It doesn’t always take that long. The rule of thumb is that a gene-edited trait can make it from discovery to market in three to five years. But in the case of Emes’ research, the transgenic corn gene adds a wrinkle that places the plants in a grey area between genetically modified and gene edited.
Curtis Rempel, vice-president for crop production and innovation with the Canola Council of Canada, said the regulatory pathway for gene-edited organisms is more clear-cut than it is for GMOs.
He said it depends on the nature of the trait. A gene-edited plant contains only genes that are already found in that plant, while a genetically modified plant takes a gene from an unrelated species.
“For instance, with Roundup Ready, it was a gene that was in a bacteria that was never found in a plant,” he said.
“And they put it in the plant and then got it to be stable and express the glyphosate-resistant trait.”
On the other hand, Emes’ high-yielding canola includes a corn transgene, which would arguably place it among GMOs, but the gene being tinkered with is not actually a foreign gene.
“Those genes do exist in brassica — you can find them in arabidopsis, for instance — they’re just poorly expressed,” said Rempel.
“It’s a matter of getting the same level of expression that we do in corn, then we can get those advantages.”
However, Rempel said the additional precautions are necessary because researchers are still working with an experimental variety.
“You don’t want pollen coming from your research trials to get into commercial production,” he said.
The distinction between plants that are genetically modified and those that are genetically edited is important largely because GMO messaging got off on the wrong foot, particularly in Europe.
Rempel said a lot of the resistance stems from misconceptions around the science. For instance, people questioned the need for glyphosate-tolerant genetic modification at all. They saw it only as a way for Big Agriculture to hawk herbicides.
However, Rempel said herbicide-resistant GMOs don’t actually act as a driver for herbicide sales.
“There’s been a number of really good scientific studies showing that by using Roundup Ready and Liberty Link products, we actually used a lot less pesticide in the Prairies,” said Rempel.
There is also a general anti-technology narrative that has taken hold in Europe. However, Rempel said there is a lot more acceptance of gene editing than there was for GMOs, even in Europe.
“People who are starting to realize that if we want to save the environment and have affordable food, we have to start looking at innovation,” he said.
“There’s a willingness now to say, ‘OK, we can’t just be opposed to every tool that comes out that benefits farmers.’ “
Gene editing is offering solutions to pressing environmental concerns. One of the big requests from canola growers is for varieties that can adapt better to the weather extremes associated with climate change. As a result, drought and heat tolerance, similar to those discovered with Emes’ work, offer great promise to the industry.
There is also great promise in developing varieties that use nitrogen more efficiently, reducing the need for chemical fertilizers.
Another area where gene editing could positively impact canola growers is insect resistance. Rempel said it’s been difficult to isolate specific genes for insect resistance through standard breeding programs, and gene editing could be a more fruitful approach.
“In canola, we don’t have a lot of genes to work with, but there are genes within other species of brassica that we could use for insect resistance,” said Rempel.
“Gene editing allows that to happen more predictably than using traditional crossing methods for plant breeding.”
And of course, it has additional environmental benefits because more insect resistance means less reliance on chemical insecticides.
Rempel said environmental benefits such as reduced chemical pesticide use, better nitrogen use efficiency and lower greenhouse gas emissions can be leveraged to sell the benefits of gene editing to a potentially skeptical public.
“I think this time around, there’s a lot more people who are willing to at least look and listen and have a conversation around what the benefits of gene editing can be,” he said.
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