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Transgene-free genome editing in poplar trees: A step toward sustainable forestry

Scientists at the VIB-UGent Center for Plant Systems Biology and VIVES University College have developed a new method to genetically improve poplar trees without introducing foreign DNA into its genome. This advancement could pave the way for the faster and more widely accepted use of gene-edited trees in forestry and the bio-based economy. The work appears in .

Gene editing tools like CRISPR are revolutionizing plant science by allowing precise and targeted improvements to plant traits, such as wood quality, disease resistance, or drought tolerance. However, in many cases, the gene-editing "machinery" is permanently integrated into the plant's DNA, creating regulatory obstacles to using the plants.

In annual crops like maize or rice, this problem is often solved by crossing plants to remove the foreign DNA. But trees like poplar take years to reach maturity, rendering this approach slow and possibly leading to the loss of desirable traits. Now, researchers led by Prof. Wout Boerjan (VIB-UGent) have developed a new method that prevents this issue.

A temporary CRISPR visit

Instead of integrating the CRISPR system into the plant's genome, the researchers used a technique called transient transformation. Using Agrobacterium tumefaciens—a bacterium commonly used in plant biotechnology—they introduced the CRISPR molecules into poplar cells, where they temporarily performed genetic edits without becoming part of the tree's DNA.

"The key innovation," says Prof. Boerjan, "is that the gene-editing tool does its job and then disappears without leaving a genetic trace behind."

To ensure that no CRISPR traces remained, the team used an advanced technique called long-read whole-genome sequencing, which scans the entire genome for even the smallest fragments of foreign DNA.

Dr. Lennart Hoengenaert (VIB-UGent), first author of the study, reports that nearly half of the regenerated poplar shoots were completely free of foreign DNA. "This is crucial," he explains, "because it brings these gene-edited trees closer to being treated like conventionally bred plants under upcoming European regulations."

"This method offers a clear and practical path to creating trees that are more sustainable, climate-resilient, and easier to regulate," says Prof. Boerjan. "It could accelerate the deployment of genetically enhanced trees, with benefits for both the environment and the bio-based economy."