The term genetically-modified organism (GMO) may cause unease in some people, but gene-editing technologies like CRISPR have unprecedented potential in a range of fields. Even so, containment measures are in development to keep them from escaping into the wild and potentially disrupting natural ecosystems. To that end, researchers at Oregon State University have now conducted a multi-year study using GMO poplar trees and found that engineering them to be sexually sterile is an effective containment measure.

In recent years, gene-editing has been used to engineer mosquitoes that don't spread malaria, crops that protect themselves from pests so harsh chemicals don't need to be sprayed, and even pigs that produce healthier bacon. Still, these benefits don't always sway the public from decrying genetic engineering as an inherently dangerous technology, as evidenced by the European Union's tough GMO laws that now even include more mundane gene-edited plants.

That said, GMOs do still need to be handled responsibly. They may be incredibly useful in some respects, but like any introduced species, there's no telling what kind of damage they could do if unleashed into the wild. Past containment measures include a scanning device developed at Rice University that can detect GMO-associated proteins in water samples.

For the new study, Oregon State researchers engineered poplar trees to essentially contain themselves. Poplars are useful trees for producing wood and paper products due to their fast growth, but the flipside of that is they can potentially be invasive if they spread beyond farms.

Poplars reproduce sexually, with female flowers producing seeds and male flowers producing pollen to fertilize them. To keep the trees contained, the scientists altered 13 genes to either prevent them from flowering, or make them grow sterile flowers.

In field tests, the Oregon State team studied 3,300 poplar trees in a 9-acre plot of land, over seven growing seasons. Year after year, the trees reliably failed to reproduce, making it easy to keep them contained. Importantly no other traits were affected, meaning the plants were still just as useful and stable as any other.

The study was conducted only on female poplars, but the researchers say that the genes targeted are found in both sexes, and should have the same effect in males. The team also points out that poplars can spread through other methods, such as root sprouts, but these are far slower and easier to contain manually.

"People have this fear that GMO trees will take over the world, but these are containment genes that make taking over the world essentially impossible," says Steve Strauss, corresponding author of the study. "If something is GMO, people assume it's dangerous – it's guilty until proven safe in the minds of many and in our regulations today. In contrast, scientists say the focus should be on the trait and its value and safety, not the method used."

The research was published in the journal Frontiers in Bioengineering and Biotechnology.