Study: New ‘Super Wood’ Uses Less Energy, Cuts Pollution

High-strength “engineered wood” is gaining popularity as a renewable building material, but manufacturing it creates chemical waste products and uses considerable energy. Now, researchers at the University of Maryland have genetically modified poplar trees to produce a high-performance, structural alternative without those drawbacks.

Engineered wood is created by removing a key component of natural wood called lignin, and then compressing what remains for greater strength, more UV light resistance and other benefits. It can replace traditional building materials like steel, cement, glass and plastic, and also has the potential to lock up the carbon it contains for longer than normal wood because it can resist deterioration, making it useful in efforts to combat climate change.

To overcome the need for volatile chemicals or energy-intensive processing, the researchers edited one gene in live poplar trees to grow wood ready for engineering without processing. The study was published online Monday in the journal Matter.

“We are very excited to demonstrate an innovative approach that combines genetic engineering and wood engineering to sustainably sequester and store carbon in a resilient ‘super wood’ form,” said Yiping Qi, a professor in the Department of Plant Science and Landscape Architecture at UMD and a corresponding author of the study. “Carbon sequestration is critical in our fight against climate change, and such engineered wood may find many uses in the future bioeconomy.”

Previously, UMD researchers successfully developed methods for removing lignin using various chemicals, and others have explored the use of enzymes and microwave technology. 

Using a technology called base editing to knock out a key gene called 4CL1, the researchers were able to grow poplars with 12.8% lower lignin content than wild-type poplar trees. This is comparable to the chemical treatments used in processing engineered wood products.

Qi and his collaborators grew their knock-out trees side by side with unmodified trees in a greenhouse for six months, and observed no difference in growth rates or significant differences in structure.

To test the viability of their genetically modified poplar, the team, led by Liangbing Hu, a visiting professor of materials science and engineering, used it to produce small samples of high-strength compressed wood similar to particle board, which is often used in building furniture.

Compressed wood is made by soaking wood in water under a vacuum and then hot-pressing it until it is nearly one-fifth of its original thickness. The process increases the density of the wood fibers. In natural wood, lignin helps cells maintain their structure, and prevents them from being compressed. The lower lignin content of chemically treated or genetically modified wood allows the cells to compress to a higher density, increasing the strength of the final product.

The team also produced compressed wood from the natural poplar, using untreated wood and wood that they treated with the traditional chemical process to reduce the lignin content.

They found that the compressed genetically modified poplar performed on a par with the chemically processed natural wood. Both were denser and more than 1.5 times stronger than compressed, untreated, natural wood.

This work opens the door to producing a variety of building products in a relatively low-cost, environmentally sustainable way at a scale that can play an important role in the battle against climate change, the researchers said.

The research was conducted in collaboration with colleagues from UMD’s Department of Materials Science and Engineering and the Institute for Bioscience and Biotechnology Research, the National Institute of Standards and Technology’s Center for Neutron Research, the U.S. Forest Service’s Forest Products Laboratory and the Department of Biological Systems Engineering at the University of Wisconsin-Madison.