Researchers extract oil from plant leaves


Gene editing allows plants to produce greater amounts of triacylglycerol in their leaves rather than just in the seed

Vegetable oil has major health benefits, and depending on the type, has the ability to lower cholesterol levels and decrease risks of cardiovascular disease.

Oil is traditionally pulled from fruit and seeds. Now, researchers at the University of Missouri-Columbia have found a way to extract oil from leaves.

They do so by boosting the production of triacylglycerol, the primary component of vegetable oil. The technique could allow farmers to harvest substantial amounts of oil from plants with large leaves such as sorghum and soybeans.

“We were studying the pathway for fatty acids and worked on a specific enzyme that is the gateway for this pathway,” said Jay Thelen, professor of biochemistry in the university’s College of Agriculture, Food and Natural Resources.

He said researchers found a new family of genes consisting of three proteins, which controls this pathway.

“Normally, plants are smart about that and they store oil in a storage tissue like a seed or a fruit. But when we knocked out the family of genes, they stored oil in the leaves. There is a small amount of oil that is always present, but just a small amount.”

Plants synthesize fatty acids when provided light and the study showed that the three proteins restrain this process in leaves.

But with the genes turned off with the editing application of CRISPR technology, the plant is able to produce greater amounts of triacylglycerol in the leaves rather than just in the seed.

Thelen said that the technology might lead to greater and cheaper production of vegetable oils, and the possibility of dual uses for leafy crops like sorghum and soybeans could place less of a burden on producing seeds with higher oil content.

One downside could be a decrease in protein, a valuable component in soybean seeds. Some 35 to 40 percent of soybean seeds is protein and 15 to 25 percent is oil.

Thelen’s lab is in the process of further testing the CRISPR method on crops to confirm its full viability.

The team carried out its study on the leaves of Arabidopsis thaliana, a plant regularly used by researchers to study plant biochemistry, and the critical issue was to ensure there were no unintended consequences.

“When we knocked out all three genes in Arapidopsis, the model plants, we noticed the plants were a little smaller,” said Thelen. “When we knocked out two genes we didn’t see smaller leaves or smaller overall growth and we still got the higher oil.

“We think that if the CRISPR approach is used it has to be a balanced approach. We don’t want to knock all the genes out, but take them out systematically. You need the right combination for higher oil production but not a deleterious effect to the plant. We don’t want to affect any part of the plant that makes it valuable in the first place or have any long-term effects.”

He said that colleagues in Brazil have been working with sugarcane and have produced a version that grows twice as tall and puts out more biomass.

“I think the possibility for oilcane is another option,” he said. “You have sugarcane, energy cane (biofuel) and in the future there could be oilcane, converting sugarcane into an oil-producing plant.”

Thelen said that they have received funding from the United Soybean Board. He said there is a lot of interest in the research from farmers.

“The funds they give are in the form of grants to researchers,” he said. “Soybean farmers sit on the board, or the panels, and they decide who gets funds. They funded some of my work. There is a lot of interest in this. They want to be part of the green revolution in some way. They welcome that.”

As for research going forward, the team has been looking at the application of CRISPR technology in other crop plants.

“We knocked the genes out in rice,” he said. “Rice is not as big a cash crop as soybean, but we used rice to look at the effects. We have a lab that transforms rice quite readily here. Sorghum is much harder, but we are planning to partner with a facility at the University of Nebraska to knock out the gene.”

The research was published in the journal Nature Communications.