CRISPR (Clustered Regularly Interspaced Short Palindromic Repeats) Gene-Editing tool offers numerous applications in genetic engineering ranging from plants, agriculture, to medicine and gene therapy. In a breakthrough research by the scientists at North Carolina State University, a CRISPR-based gene manipulated poplar trees were bred to achieve decreased lignin content, paving way for a sustainable generation of wood, pulp, and fiber.
Led by Rodolphe Barrangou, a renowned CRISPR expert from NC State, Jack Wang, a tree geneticist, and their team employed advanced predictive modeling techniques to establish objectives aimed at reducing lignin levels. This would ultimately cut the costs of wood fiber products, make the consumables greener, and more efficient for future use. The study was published in an esteemed journal Science.Â
The Power Tool- CRISPR
The researchers worked on two main aspects, enhancing carbohydrate-to-lignin (C/L) ratio, and increasing the ratio of two crucial components of lignin- syringyl to guaiacyl (S/G)- in poplar trees. According to Barrangou and Wang, achieving these specific chemical traits in the trees would create an optimal condition for fiber production.
Using a machine-learning model, the team employed nearly 70,000 distinct gene-editing approaches to predict and categorize strategies aimed at 21 significant genes linked to lignin production. These strategies involved altering multiple genes simultaneously. Through this process, they identified 347 strategies out of which, over 99% of them targeting at least three genes.
From this pool of strategies, the researchers handpicked the top seven that the modeling indicated would result in trees achieving the desired chemical characteristics. These characteristics included a 35% reduction in lignin compared to unmodified, wild trees, carbohydrate-to-lignin (C/L) ratios more than 200% higher than those of wild trees, syringyl to guaiacyl (S/G) ratios also more than 200% higher than those of wild trees, and also, tree growth rates that were comparable to wild trees.
Using seven short-listed parameters, the researchers generated 174 lines of poplar trees through CRISPR editor. After a sufficient period of growth, the trees’ analysis confirmed lower lignin content to up to 50% in some propagated varieties, while others also showed an approximate increase of 228% in the C/L ratio.
The researchers further experimented a four to six gene edit model, and found an interesting exhibition of enhanced minimisations in lignin levels (up to 32% in three gene edits). Contrastingly, single gene edits had negligible impact on lignin content. This highlights the advantage of using CRISPR technology to make multiple gene edits, which can significantly enhance fiber production.
The researchers exclaimed that trees with lower lignin content could significantly enhance pulp yield and decrease the production of “black liquor,” a primary byproduct of pulping. These findings suggest that mills could potentially increase the production of sustainable fibers by up to 40%.
CRISPR Edits in Climate Study
The scientists also tested their model on climate impacts. The CRISPR edited poplar trees, along with enhanced pulp production were calculated to decrease the levels of greenhouse gasses by up to 20%, if deployed at industrial scale.Â
According to Daniel Sulis, a postdoctoral scholar at NC State and the paper’s first author, this comprehensive and multidisciplinary approach promises holistic solutions having tremendous potential to enhance environmentally and economically crucial wood characteristics, while mitigating the carbon footprint associated with fiber and pulp production at the same time. The team in their future endeavors aim at continued testing of their gene-edited tree models on measuring greenhouse effects compared to the efficiency of wild trees.
