University of Calgary Faculty of Science plant biologists find solution to ‘green seed’ problem in canola
The last thing University of Calgary PhD student Logan Skori’s father, Ellie, and other canola farmers want to see when they harvest their crops are green seeds.
Late season, non-lethal frost prevents chlorophyll, a photosynthetic pigment in the seeds of the valuable oilseed crop, from naturally breaking down, or “degreening,” and producing a high-quality yellow embryo at seed maturity.
Grade No. 1 canola cannot have more than two per cent of green seeds, but frost can substantially increase this percentage. When green seeds are processed to extract canola oil, the chlorophyll reduces the oil’s storability and quality.
Farmers receive a lower price for frost-damaged green seed canola, which costs them an estimated $150 million annually.
Now, Skori and a team of Faculty of Science researchers led by Dr. Marcus Samuel, PhD, have developed a gene-based technology to produce canola plants that can withstand late-season frost and still produce high-quality seed.
“We’ve been able to create canola lines that can degreen properly,” says Samuel, associate professor of integrative cell biology in the Department of Biological Sciences.
Alberta farmers grow 35 per cent of all Canadian canola, for both domestic and international markets that’s worth $27 billion a year.
“If our research was integrated into canola-breeding programs, it would serve like crop insurance for the farmers, who ultimately take the financial burden for frost-damaged canola,” Skori says.
Skori and Mendel Perkins, a member of Samuel’s research group when the study was done (and is now doing his PhD at the University of British Columbia), are co-lead authors of the team’s study. Their paper, “Genetic Manipulation of ABI3 Confers Frost-Tolerant Seed Degreening in Canola,” is published in the peer-reviewed Plant Biotechnology Journal.
‘Master regulator’ controls degreening
The new research builds on previous work by Samuel’s group published in 2013, which detailed the molecular pathways for seed degreening in Arabidopsis, a cousin of canola and a model plant system for biological research.
In that research, the group found a “master regulator,” a transcription factor called ABI3 (Abscisic Acid Insensitive 3), a protein that controls chlorophyll breakdown and seed maturity. The team showed that through genetic manipulation, the expression of ABI3 could be increased, or “overexpressed,” in Arabidopsis plants.
“This up-regulation of ABI3 in seed tissue enhanced the seed degreening system and allowed the seed to break down chlorophyll following instances of frost,” Skori says.
In their new work, Samuel’s research group were able to reduce the amount of chlorophyll in the genetically modified canola lines by 50 to 60 per cent after the plants were exposed to non-lethal frost (-4 C for six hours).
“We also saw other benefits in the modified canola lines,” Samuel notes. The seed pods’ structure was stronger, so he says that would likely reduce another canola crop problem, “pod drop,” where the whole pod falls to the ground.
PhD student Neil Hickerson, who looked at oil quality of the modified canola plant lines, says they had increased levels of nervonic acid, a fatty acid important for brain health. At the same time, the plants had higher levels of another fatty acid, oleic acid, compared with linoleic acid.
“That improves the stability of the canola oil for storage, as well as its overall cooking properties,” Hickerson says.
Next step is improved commercial seed
The research group’s next step is to develop a method to knock out the negative regulator of the ABI3 expression directly in the canola plant. “If you take out the negative regulator, you automatically see an up-regulation of ABI3, so it is the same result,” Samuel says.
This approach would be relatively simple and inexpensive for seed producers to incorporate in canola hybrid lines, and be more readily accepted by consumers concerned about genetically modified organisms, he says.
Samuel’s group has a collaborative research and development grant from the Natural Sciences and Engineering Research Council of Canada (NSERC) to work with agricultural firm Nutrien on this next step. Samuel expects commercial frost-protected seed lines to be available within five years.
Skori, who’s headed home this fall to help with the canola harvest on the family farm, says, “This technology will benefit canola farmers and help them produce high-quality crops regardless of the environmental conditions the plant must face.”
“Canola is one of Canada’s most valuable crops,” says Bruce Harrison, Nutrien’s senior director of breeding innovation. “Innovation such as this will help ensure Canada builds on its position of delivering the best quality in the world.”
The new study was funded by NSERC. Samuel’s laboratory also was supported by the private, not-for-profit Alberta Crop Development Industry Fund which ended operations last year.