2023-07-14 21:42:51
An aerial photo shows a forest area where spruce trees used to stand after suffering from drought stress in a forest near Iserlohn, western Germany, on July 12, 2023. INA FASSBENDER / AFP
When it comes to trees, biochemist Rodolphe Barrangou, a professor at North Carolina State University in Raleigh, makes no secret of his admiration. “They have exceptional longevity, sometimes lasting several centuries, put up with variations in climate on all scales, and all this while remaining in the same place: this physical and chemical resilience is incredible,” he said. “Except that, to make paper or coatings out of them, it complicates the process.”
The French researcher, one of the pioneers of the CRISPR genome editing technique, believes he has found the solution. In an article published in the journal Scienceon Friday, July 14, his laboratory and that of his geneticist colleague Jack Wang announced that they have developed poplars capable of boosting the economic productivity of the forestry sector, while reducing its ecological footprint.
At the heart of the challenge lies lignin. Along with cellulose and hemicelluloses, it is one of the three main constituents of wood, giving the material its famous strength. But to transform the pulp of a pine or poplar tree into paper pulp, it has to be removed. Despite the progress made, the process still requires the pulp to be heated to 170°C and then exposed to soda or sulfur. With a lot of waste. In 2021, half of the 1.7 billion tonnes of raw material extracted generated waste, including the highly polluting black liquor.
Over the last 20 years, geneticists have highlighted the role of numerous genes in the production of this lignin. But to optimize the recipe, two tools were missing, which the Raleigh team has now been able to use. Firstly, artificial intelligence: Using the knowledge already accumulated by Wang’s laboratory on 21 genes of interest, the researchers asked a neural network to examine some 70,000 possible combinations of mutations.
The scientists set the three constraints of reducing lignin by at least 15%, modifying its composition to make it less resistant, and at the same time increasing the amount of carbohydrates. The AI initially came up with 347 combinations. Further increasing their demands, the researchers finally selected seven strategies, enabling a 35% reduction in lignin through simultaneous modification of 4 to 6 genes.
“But computer predictions are only valid if confirmed in the real world,” said Barrangou. This time, it was the CRISPR genome-editing technique that enabled the transition from the computer to the laboratory, and then to the greenhouse. Deactivating certain genes, reducing the expression of others… these seven strategies led to the production and planting of 147 lines.
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