Paper is renewable, but its production creates millions of tons of chemical waste and releases large amounts of greenhouse gases. But papermaking could become less harmful to the environment thanks to genetically modified trees presented by American researchers in the leading scientific journal Science (“Multiplex CRISPR editing of wood for sustainable fiber production“).
“We’re creating a more sustainable forest,” Rodolphe Barango of North Carolina State University, who led the study, said in a (“Building a Better Forest Tree With CRISPR Gene Editing“) press release. The main component of paper is cellulose, the same substance that cotton is made of. The most difficult stage of paper production is separating the cellulose from the lignin, the hard, woody material that keeps trees standing.
The lignin removal process requires chemicals and water and emits more than 150 million tons of carbon each year. But it could become cleaner thanks to the new study’s genetically modified poplars, which contain up to 50% less lignin. If the average paper mill used such poplars, the researchers say, production would increase by 40 percent, carbon emissions would decrease by 20 percent, and profit over the lifetime of the plant would increase by about $1 billion.
Although the experimental poplars are genetically modified, they do not carry genes from other organisms, which potentially simplifies their licensing in some countries (and possibly in Europe in the future).
Tens of thousands of combinations
Previous attempts to intervene to reduce lignin in paper wood have met with obstacles, as its production in trees is controlled by hundreds of genes. The approach used in the latest study was a computational model that looked at 70,000 combinations of interventions across multiple genes simultaneously.
The researchers then selected the 174 most promising combinations and applied them to the plants using the molecular tool CRISPR, which can be programmed to cut DNA molecules at very specific locations so that corresponding genes are turned off or others are added in their place.
The genetically modified plants were grown in a greenhouse for six months, when it was found that the cellulose to lignin ratio was improved by 230% compared to conventional poplars. The fact that the new varieties would offer a significant economic benefit, in addition to the environmental one, will be a strong incentive for their adoption, the researchers hope.
But first they will have to proceed with field tests and monitor the trees for years. Since lignin plays an important role in structural stability and protection from insects, researchers will need to make sure the trees withstand storms and insect attacks.
