Genetically modifying plant protein to yield more vegetable oil

At the Nanyang Technological University, Singapore (NTU Singapore), researchers have been successful in genetically modifying a plant protein that is accountable for oil accumulation in edible nuts and plant seeds.

Illustrating their patent-pending technique, the model plant Arabidopsis housed around 15 to 18% more oil in its seeds when it was grown with the modified protein while being subjected to laboratory conditions. For the farming sector, determining ways to make crops provide more oil in their seeds is a holy grail.

But the majority of the oil-producing crops—like oil palm, sunflower, soybean, peanut, and rapeseed—already consist of a high percentage of oil in their seed or fruit. Also, it is difficult to increase their oil content via traditional crop crossbreeding methods.

On a general basis, vegetable oils are used in food processing, perfumes, soaps, biofuels, and the global market for them has been estimated to be nearly US$241.4 billion in 2021 and is expected to increase to US$ 324.1 billion by 2027.

Furthermore, growing the yield of oil from plants could aid the world in its thirst for sustainability, thereby assisting to decrease the amount of arable land required for oil-yielding crops. The mystery to helping plants store more oil in their seeds is one of their proteins called WRINKLED1 (WRI1).

Researchers have recognized for more than 20 years that WRI1 plays a significant role in regulating plant seed oil production. Currently, for the first time, a high-resolution structure of WRI1 has been pictured and reported by the NTU team, collaboratively headed by Associate Professor Gao Yonggui and Assistant Professor Ma Wei from the School of Biological Sciences

Having reported in the scientific journal Science Advances, the team elaborated on the molecular structure of WRI1 and how it merges to plant DNA—which signals to the plant how much oil to accumulate in its seeds.

Depending on the knowledge that the atomic structure of the WRI1-DNA complex was disclosed, the team altered WRI1 to improve its affinity for DNA in a bid to enhance oil yield. In this method, a few portions of WRI1 were chosen for alterations to enhance its binding to DNA and various forms of WRI1 were generated.

Such candidate WRI1s were then additionally tested to evaluate their potential to trigger oil production in plant cells. As anticipated by the team, they displayed that their altered versions of WRI1 increased DNA binding 10-fold than the original WRI1—eventually resulting in more oil content present in its seeds.

Being able to see exactly what WRI1 looks like and how it binds to DNA that is responsible for oil production in the plant was the key to understanding the entire process.”

Gao Yonggui, Associate Professor and Structural Biologist, Nanyang Technological University

Yonggui added, “WRI1 is an essential regulator that informs the plant how much oil to store in its seeds. Once we were able to visualize the ‘lock’, we then engineered the ‘key’ that can unlock the potential of WRI1.”

How modifying WRI1 works

Examining at the atomic level, the WRI1 protein’s crystal structure, and the double helix DNA strands to which it merges, the team observed this DNA binding domain was conserved extensively.

This means that there were little to no variations, indicating it could be a general binding mechanism for several plant species. Utilizing this crystal structure of WRI1 as the so-called “target,” the team further looked to alter WRI1, to improve the binding affinity of the protein for its target DNA.

Then, the instructions followed for coding this modified WRI1 protein is introduced into the target plant cells, following which the plant will utilize this new so-called “set of instructions” whenever it generates WRI1.

In laboratory experiments to note how the modified WRI1 impacts oil accumulation, both the modified protein and the unmodified form were injected into Nicotiana benthamiana leaves, and an examination of triacylglycerol (a significant form of dietary lipid in fats and oils) levels was performed.

The modified WRI1 protein produced highly considerable spikes in triacylglycerol production than the control plant introduced with the WRI1 unmodified form. Consecutive experiments displayed that the oil content in the seeds of the modified Arabidopsis thaliana contained more oil compared to the unmodified form.

Furthermore, the offspring of this genetically modified plant will bear the similar modified WRI1 protein and generate more oil in their seeds.

Assistant Prof. Ma, a plant molecular biologist who has been learning WRI1 since his postdoctoral training, stated modifying WRI1 to enhance its binding to DNA was a logical shift for the team.

We know that WRI1 is a protein that binds to a plant’s DNA sequence and sets off a specific chain of instructions that regulates the accumulation of oils in the seeds. The stronger the binding – the more oil the plant will concentrate in its seeds.”

Ma Wei, Assistant Professor, School of Biological Sciences, Nanyang Technological University

Professor Ma added, “Therefore, we chose to improve this portion of WRI1 that binds to its target DNA, which is highly conserved across many seed-bearing plants. Being highly conserved means many species of plants will have the exact same mechanism that can be modified, so we should be able to translate our oil-yielding modification easily to many different types of crops in future.”

Assistant Professor Ma explained, “Plant seed oil is vital for the human diet and is used in many important industrial applications. Global demand for plant oil is increasing very quickly and our research contributes to efforts to improve seed oil production in a sustainable manner, and potentially reducing the environmental impact of agriculture.”

Going forward, the group has filed a patent for their technique of gene modification via NTUitive, the University’s innovation and enterprise office, and is looking for industry collaborators to commercialize their invention.

This study is lined up with the NTU2025 strategic plan and the University’s Sustainability Manifesto, which goals to research and develop new technologies ahead of a greener future.

Providing a separate expert comment, Michael Fam Chair Professor William Chen, Director of the Food Science & Technology Program at NTU, stated there are a few methods to handle world hunger. This includes increasing the amount of food that has been produced or growing the calories and nutritional value of the food produced.

In a world that has limited arable land for agriculture, advanced technologies to grow more food with higher nutrition value is required if we hope to tackle world hunger. When we can increase the fat content in edible seeds and nuts, a person can eat a lesser amount but still feel full, due to the increase in calories consumed.”

William Chen, Michael Fam Chair Professor and Director, Food Science & Technology Programme, Nanyang Technological University

Chen added, “So instead of growing more crops to feed more people, we should also look at methods where the crops grown have more calories and nutrition, so that the same amount of food can feed more people.”