Using CRISPR to genetically edit trees could drastically reduce the energy footprint of the paper industry.
Making paper requires a lot of energy and water, he says Jack Wang at North Carolina State University. In 2021, the global carbon footprint of the industry was estimated at 190 million tons – a figure that is expected to rise until 2030, when paper production is projected to peak.
One of the biggest energy drains in the papermaking process is the removal of the lignin polymer from the wood, says Wang. Within the structure of the wood, lignin is bound to cellulose, the molecule that makes up paper. . Separating the two requires high temperature and pressure, as well as lots of water, Wang says. But lignin also “contributes to the structure, integrity and resilience of trees,” he says. Rodolfo Barrangou also at North Carolina State University.
Wang, Barrangou and their colleagues wondered if they could genetically edit poplar trees, which are widely used to make paper, to have a lower lignin concentration and maintain their structure.
To do this, they used machine learning to analyze the poplar genome and highlight gene combinations that they could edit using CRISPR, and the program identified 69,123 ways to edit 21 genes.
The researchers analyzed this data to determine which combinations had the best chance of reducing a tree’s lignin content while ensuring it stayed strong, finding that only 0.5 percent hundred of these editing methods fit the bill. They chose seven that they considered particularly robust, from which they grew 174 different variants of CRISPR-edited poplars.
After six months of growth, the team found that the lignin content in the edited trees was up to 49 percent lower than in the unedited trees.
“At a time when climate change is so important, finding tangible and potential real-world solutions to substantially reduce carbon emissions from pulp and paper production is very exciting,” says Wang.
The trees have been growing for about a year and show no major adverse effects on their structure, Barrangou says. The researchers plan to plant several of them in a forest to study the long-term effects of gene editing, and are exploring the technique for other types of trees used to make paper.
“This could be the beginning of a new era of sustainable forestry,” says Barrangou. Wang says he hopes these trees could see large-scale commercial use by the 2040s.