Researchers at the University of Maryland genetically modified poplar trees to produce high-performance, structural wood without the use of chemicals or energy-intensive processing. Made from traditional wood, engineered wood is often seen as a renewable replacement for traditional building materials like steel, cement, glass and plastic. It also has the potential to store carbon for a longer time than traditional wood because it can resist deterioration, making it useful in efforts to reduce carbon emissions.

Before wood can be treated to obtain structural properties such as increased strength or UV resistance, it must be stripped of its lignin. Although methods exist for removing lignin, such as treatment with chemicals or enzymes and microwave technology, they can result in considerable waste. Now, researchers have successfully genetically engineered wood, using base editing, to produce high-performance, structural wood without the use of chemicals or energy intensive processing.

The research was published in Matter in a paper entitled, “Genome-edited Trees for High-Performance Engineered Wood.”

“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, PhD, professor in the department of Plant Science and Landscape Architecture at the University of Maryland. “Carbon sequestration is critical in our fight against climate change, and such engineered wood may find many uses in the future bioeconomy.”

By knocking out the 4CL1 gene—using the cytosine base editor nCas9-A3A/Y130F—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.

The knock-out trees were grown side by side with unmodified trees in a greenhouse for six months. They observed no difference in growth rates and no significant differences in structure between the modified and unmodified trees.

To test the viability of the genetically modified poplar, it was used to produce high-strength compressed wood similar to particle board, which is often used in building furniture. Typically, compressed wood is made by soaking wood in water under a vacuum and then hot-pressing it until it is nearly 1/5 of its original thickness. In natural wood, lignin helps cells maintain their structure, and prevents them from being compressed. The lower lignin content of the genetically modified wood (or chemically treated wood) allows the cells to compress to a higher density, increasing the strength of the final product.

The findings of the genetically modified wood were similar to the chemically treated wood. More specifically, the authors write, “by soaking this [genetically modified] wood in water and hot pressing, we achieved a tensile strength of 313.6 ± 6.4 MPa, 5.6 times higher than that of natural 4CL1 knockout wood and 1.6 times higher than that of densified wild-type wood. This strength is comparable to chemically treated densified wood (320.2 ± 3.5 MPa).”

To further evaluate the performance of their genetically edited trees, 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. The compressed genetically modified wood had a tensile strength comparable to aluminum alloy 6061 and the compressed wood that had been chemically treated.

This work opens the door to producing a variety of building products in a low-cost, environmentally sustainable way at a scale that can play an important role in the battle against climate change. The authors write that, “this success highlights genome editing’s potential to create other engineered wood materials with enhanced properties, contributing to a CO2-negative bioeconomy by providing renewable alternatives to traditional materials.”



Source: genengnews.com