Researchers at North Carolina State University (NC State) have achieved successful implementation of CRISPR gene-editing technology to cultivate poplar trees with reduced lignin levels, a significant obstacle in the sustainable production of wood fibers. Their groundbreaking research, recently published in the journal Science, holds the promise of revolutionizing fiber production, making it more efficient, eco-friendly, and cost-effective for various products, ranging from paper to diapers.
The Potential of CRISPR
Under the guidance of CRISPR pioneer Rodolphe Barrangou and tree geneticist Jack Wang, the NC State research team utilized predictive modeling to establish targets for lowering lignin content, increasing the carbohydrate-to-lignin (C/L) ratio, and enhancing the ratio of two crucial lignin building blocks: syringyl to guaiacyl (S/G) in poplar trees. This combination of chemical characteristics represents an ideal state for fiber production, according to Barrangou and Wang.
Barrangou, the Todd R. Klaenhammer Distinguished Professor of Food, Bioprocessing, and Nutrition Sciences at NC State and co-corresponding author of the paper expressed their excitement about the research, stating, “We are harnessing the power of CRISPR to cultivate a more sustainable forest. CRISPR systems offer the flexibility to edit not only single genes or gene families but also allow for more extensive enhancements to wood properties.” With the application of CRISPR technology, the potential for a greener, more cost-effective, and more efficient fiber production process seems closer than ever before.
To achieve the most effective gene-editing strategies, the team employed a machine-learning model to analyze nearly 70,000 distinct approaches for gene editing. These strategies targeted 21 crucial genes linked to lignin production, with some involving the simultaneous modification of multiple genes. Through this method, the researchers successfully identified 347 optimal strategies, where over 99% of them focused on editing at least three genes simultaneously.
After analyzing the data, the researchers identified seven optimal gene-editing strategies that were predicted to lead to poplar trees with desired chemical traits. These traits included a reduction of up to 35% in lignin content compared to wild trees, a more than 200% increase in the carbohydrate-to-lignin (C/L) ratio, and a similar increase in the syringyl to guaiacyl (S/G) ratio. Additionally, the goal was to maintain tree growth rates comparable to wild trees.
CRISPR Explained
CRISPR gene editing
Using CRISPR gene editing, the researchers created 174 lines of poplar trees based on the identified strategies. After a six-month period of cultivation in an NC State greenhouse, the examination of these trees revealed lignin reductions of up to 50% in certain varieties and a remarkable 228% increase in the C/L ratio in others.
Notably, the study showed that trees with four to six gene edits exhibited more significant reductions in lignin, while those with three gene edits still achieved up to a 32% reduction. Single-gene edits did not result in significant lignin reduction, highlighting the advantages of utilizing CRISPR for making multi-gene changes to enhance fiber production.
The researchers also assessed the impact on pulp production and found that reduced lignin content in trees could lead to increased pulp yield and reduced “black liquor,” a primary byproduct of pulping. This could potentially boost sustainable fiber production in mills by up to 40%.
Moreover, the efficiencies achieved in fiber production could lead to a reduction of up to 20% in greenhouse gas emissions associated with pulp production if these traits are successfully incorporated into trees on an industrial scale.
Realm of forestry and fiber production
The significance of this research extends beyond the realm of forestry and fiber production. Forest trees play a crucial role in mitigating climate change as the largest biogenic carbon sink on Earth. Efforts to enhance their resilience, productivity, and sustainability are of paramount importance in addressing environmental challenges.
As Dr. Jack Wang, assistant professor and director of the Forest Biotechnology Group at NC State and co-corresponding author of the paper, expressed, “Multiplex genome editing provides a remarkable opportunity to improve forest resilience, productivity, and utilization at a time when our natural resources are increasingly challenged by climate change and the need to produce more sustainable biomaterials using less land.” With these advancements in gene-editing technology, there is hope for a greener and more sustainable future for both the economy and our planet.
