Genetically Modified Poplar Cuts GHG

Every year, paper mills generate millions of tons of chemical waste and more than 150 million tons of greenhouse gas (GHG) emissions. But scientists have found a way to reduce that burden.

Photo Insert: Jack Wang and Rodolphe Barrangou, biotechnologists at North Carolina State University (NC State), and their colleagues built a computer model to predict how changing poplar genes related to lignin production might impact wood composition.

By using CRISPR gene-editing tools, they grew engineered poplar trees with far less lignin than usual. Milling these trees, they argue, could lower papermaking pollution while saving the industry billions of dollars, reported Robert F. Service for Science magazine.

This is impactful work,” says Vânia Zuin Zeidler, a chemist at Leuphana University of Lüneburg who wrote a companion piece in Science describing the result’s significance.

Rather than remediate an existing problem, they are trying to prevent pollution.

Papermakers start by cutting wood into small chips. Water and chemicals are added to break apart the lignin structures and separate the wet pulp of cellulose fibers, which are pressed and dried into paper.

Researchers have tried to breed and engineer trees with lower lignin content, with less success. Lignin is woven together from three precursor compounds in a process governed by 11 gene families and hundreds of genetic and metabolic regulatory elements.

Jack Wang and Rodolphe Barrangou, biotechnologists at North Carolina State University (NC State), and their colleagues built a computer model to predict how changing poplar genes related to lignin production might impact wood composition.

After testing 70,000 gene-editing combinations, they found that 99.5% of these changes would be bad, leading to drooping limbs and stems.

But 347 combinations, each comprising few individual gene changes, safely boost cellulose, cut lignin, or both, thus improving the papermaking potential of the trees. The best varieties had their lignin content cut by 49.1% and their cellulose-to-lignin content rose by 228%.

If a paper mill uses these varieties, the team said, it could boost paper output by 40%, cut GHG emissions by 20% and raise lifetime profits by about $1 billion.

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