Engineering cell walls for a sustainable plant-based future
September 4, 2024
-written by Lennart Hoengenaert, a postdoctoral researcher at the VIB-UGent Center for Plant Systems Biology
Did you know that one of the most underutilized resources on our planet is something we see every day? It is all around us—plants.
While we usually think of plants as sources of food and medicine, they hold far more potential than we realize. Imagine plastics, which are typically made from fossil fuels. Using plants instead could be a game-changer in our fight against climate change.
But there's a catch.
The efficient use of plant biomass in industry is currently hindered by a serious obstacle: a complex polymer present in the plant’s cell wall called lignin. Lignin acts like a glue, holding everything together and making it difficult to extract valuable components from the cell wall, which are essential for the production of biofuels and biomaterials.
In the lab of Prof. Wout Boerjan, at the VIB-UGent Center for Plant Systems Biology, we are working on a solution to this problem by studying the composition of the plant cell wall. Unlike animal cells, plant cells are surrounded by a thick and rigid wall made up of three main polymers: cellulose, hemicellulose (both polymers of simple sugars), and lignin. While cellulose and hemicellulose are crucial for producing biofuels and other products, lignin complicates their extraction.
Modified lignin
You might think a possible solution is simply to reduce the amount of lignin in the plant cell wall, but, unfortunately, it is not as simple as that. Lignin strengthens the plant and is important for the transport of water. Therefore, we explored another fascinating approach: modifying the composition of lignin itself. Typically, lignin is made up of three building blocks (which we call H-units, G-units, and S-units), but plants have a unique ability to incorporate other types of building blocks as well. One of these is the natural compound scopoletin.
By introducing scopoletin into the lignin polymer, we can create weak links in the chain that are easier to break in the biorefinery. This increases the amount of fermentable sugars that can be released from the plant, which can then be turned into a variety of products, including biofuels and bioplastics.
During my PhD research, I overexpressed the genes responsible for the biosynthesis of scopoletin to produce plants with a lignin polymer that is readily cleavable within the biorefinery. The results were promising! Our plants not only produced large amounts of scopoletin but also had yellow cell walls that fluoresced under the microscope—clear signs that scopoletin was being incorporated into the lignin polymer.
And the best part? These modified plants showed a 40% increase in sugar release during processing, making them far more efficient in the biorefinery.
But this is just the beginning. My colleague Nette is now translating this research from the lab to the field, using poplar trees as a model. Let’s embrace the potential of what we have most abundantly on Earth—plants—and move toward a sustainable bio-based economy.
Publication
Lennart Hoengenaert et al., Overexpression of the scopoletin biosynthetic pathway enhances lignocellulosic biomass processing. Sci. Adv. 8, eabo5738(2022). DOI:10.1126/sciadv.abo5738
Read more
