New genetically modified plant to produce biodiesel

Researchers from the Tokyo Institute of Technology (Tokyo Tech) have successfully introduced an engineered lipid remodelling system into a transgenic plant to enhance biofuel production.

Triacylglycerols from plants can be used to produce environmentally friendly and renewable biodiesel, and there has been great interest in using genetic engineering to enhance triacylglycerol levels in plant vegetative tissues.

A team at the Tokyo Institute of Technology led by Mie Shimojima and Yuka Madoka recently developed a lipid remodelling system that could be introduced in transgenic plants to boost the levels of triacylglycerol production in leaves and roots.

Plants usually obtain phosphorous, an essential mineral for their growth, in the form of a phosphoric acid salt, known as inorganic phosphate.

During inorganic phosphate deficiency, cell membrane materials called phospholipids are broken down to free up phosphorous while accumulation of triacylglycerols is induced.

However, most plant triacylglycerols are synthesised and stored in seeds, which constitute only a small part of the plant.

Moreover, while triacylglycerols are also synthesized in non-seed plants, their concentrations are usually very low in vegetative tissues such as leaves.

The team started out by comparing how the Arabidopsis—a type of small flowering plant related to cabbage and mustard—responds to inorganic-phosphate- and nitrogen-depleted conditions.

While both conditions resulted in triacylglycerol accumulation, the biomass of plants grown under nitrogen-depleted conditions was markedly lower than that under inorganic phosphate starvation.

Using these findings, the researchers created a lipid remodelling system and introduced it into transgenic Arabidopsis plants, which caused them to show higher levels of triacylglycerol accumulation compared with the typical form of the plant.

Other studies have shown an increase in triacylglycerol levels in vegetative tissues, but these studies required soil with adequate nutrients for plant growth.

Notably, the team at Tokyo Tech was able to achieve results by using nutrient-depleted growth conditions and by modifying only a single gene that was introduced into the transgenic plants in this study.

The study’s results are promising introducing more genes could further elevate triacylglycerol levels in the plants.

The team is currently also investigating whether this novel lipid remodelling system can be applied to crop plants.

If successful, the production and subsequent consumption of biodiesel at economically viable levels may be a reality in the not-too-distant future.

The study was published in the Frontiers in Plant Science journal under the title of ‘An engineered lipid remodeling system using a galactolipid synthase promoter during phosphate starvation enhances oil accumulation in plants’.