Unlocking the Potential for Lipid Production in Plants

PhD student Michal Pyc in the Phytotron (photo by K. White)

As biotechnology seeks to pave the way to a more sustainable future, researchers in the Department of Molecular and Cellular Biology have identified a new tool in one of our closest allies: plants.

Prof. Robert Mullen and PhD student Michal Pyc have discovered a new protein that regulates the production of structures in plants called lipid droplets. Lipid droplets are small structures inside plant cells made up of lipids (fats). Their primary purpose is to store neutral lipids which cells rely on as a source of energy when their own nutrient sources are limited, but they also play an essential role in plant development and growth. Although lipid droplets have been observed since the early days of microscopy, the last decade has seen a huge push to understand and repurpose these dynamic structures to produce important bioproducts such as biofuels and nutritional supplements.

“Lipid droplets are exciting,” says Pyc. “It’s a new dimension of cell biology that is getting more and more attention.”

One mechanism plant cells use to regulate the formation of lipid droplets is through proteins called “LDAPs”, but how cells use these proteins to influence lipid droplets remains unclear. To discover what other unique proteins might cooperate with the LDAPs, the researchers used the proteins as “bait” in experiments designed to identify potential interacting proteins. They quickly identified a new protein that works together with LDAP at the surface of lipid droplets, which they coined LDAP-interacting protein (LDIP). When the researchers analyzed mutant plants with non-functional LDIP, they found that the plants produced a smaller number of lipid droplets that were much bigger and filled with more neutral lipids compared to plants with normal LDIP.

Pyc believes LDIP plays an essential role in directing the size and composition of lipid droplets. The larger size of droplets in LDIP-depleted cells suggests that LDIP helps maintain separate and distinct lipid droplets. Additionally, the increased proportion of neutral lipids within the droplets indicates LDIP also may direct the type and amount of lipids being stored in droplets. That means that by modifying LDIP activity, plant breeders could have a valuable tool to create crops with “mega” lipid droplets that would be ideal for industrial applications.

Pyc and Mullen carried out their research on the oft-studied model plants, Arabidopsis thaliana and Nicotiana benthamiana (a close relative of tobacco). But when it comes to how widely this research could be used, the sky’s the limit.

“The similarity of some lipid droplet proteins across different species is so high that this information can carry over to many different production systems beyond plants, such as yeast or algae,” says Pyc. “This work could be used to tailor lipid droplet production to favor the synthesis of specific lipids in any of these systems.”

This project was completed in collaboration with researchers from the US Department of Agriculture, University of North Texa, and University of Göttingen. Funding was provided by the Natural Sciences and Engineering Research Council of Canada, the US Department of Energy, the German Research Foundation and the Studienstiftung des Deutschen Volkes. 

Read the full article in The Plant Journal.

Read about other CBS Research Highlights.