Building a better forest tree with CRISPR gene editing

Researchers at North Carolina State University used a CRISPR geneediting system to breed poplar trees with reduced levels of lignin, the major barrier to sustainable production of wood fibers, while improving their wood properties. The findings hold promise to make fiber production for everything from paper to diapers greener, cheaper and more efficient.

Led by NC State CRISPR pioneer Rodolphe Barrangou and tree geneticist Jack Wang, a team of researchers used predictive modeling to set goals of lowering lignin levels, increasing the carbohydrate to lignin (C/L) ratio, and increasing the ratio of two important lignin building blocks – syringyl to guaiacyl (S/G) – in poplar trees. These combined chemical characteristics represent a fiber production sweet spot, Barrangou and Wang say.

"We're using CRISPR to build a more sustainable forest," said Barrangou, the Todd R. Klaenhammer Distinguished Professor of Food, Bioprocessing and Nutrition Sciences at NC State and co-corresponding author of the paper. "CRISPR systems provide the flexibility to edit more than just single genes or gene families, allowing for greater improvement to wood properties."

The machine-learning model predicted and then sorted through almost 70,000 different gene-editing strategies targeting 21 important genes associated with lignin production – some changing multiple genes at a time – to arrive at 347 strategies; more than 99% of those strategies targeted at least three genes.

From there, the researchers selected the seven best strategies that modeling suggested would lead to trees that would attain the chemical sweet spot. From these seven strategies, the researchers used CRISPR gene editing to produce 174 lines of poplar trees.

Image source: Chenmin Yang, NC State University.