A biotechnology company in California that aims to create fast-growing trees that can quickly absorb atmospheric carbon dioxide announced its first experimental results: the company’s genetically enhanced poplars grew more than 1.5 times faster than non-modified poplars in laboratory tests. Plant scientists welcome the news, but warn that much more work is needed before the modified trees begin to contribute to mitigating climate change.
“It’s a big first step,” says Sophie Young, a plant biologist at Lancaster University, who is not involved in the project. But, she adds, there is “a big caveat”: The trees were grown in a carefully controlled greenhouse as opposed to the outdoors.
Scientists and environmentalists have promoted tree planting as a promising and easily scalable way to reduce atmospheric carbon dioxide levels, the main cause of planetary warming. Trees, which consist of about half carbon by dry weight, absorb the gas from the air and convert it into stable forms of carbon, such as wood and roots.
But how quickly trees absorb carbon is limited by many factors. A key constraint is the rate of photosynthesis, the biochemical process that trees use to convert carbon dioxide into sugars and ultimately into wood. Almost all trees use a relatively inefficient form of photosynthesis that produces a toxic byproduct called phosphoglycolic acid, which plants must then remove through a process called photorespiration. This uses energy that could otherwise go into growth.
To bypass the problem, researchers from a company called Living Carbon used a bacterium to introduce genes from pumpkin and green algae into poplars. The foreign genes allowed the trees to have lower rates of photorespiration and to recycle carbon from phosphoglycolic acid into sugars necessary for growth.
Other researchers had previously incorporated a similar trait into tobacco plants. But, “as far as I know, [the approach] has never been tested before in a tree,” says Steve Strauss, a forest geneticist at Oregon State University, Corvallis, who is a member of Living Carbon’s scientific advisory board and collaborates with the company on research.
The company Living Carbon, founded in 2019, cultivates genetically modified poplars inside a converted music recording studio in San Francisco. Some of the trees have grown so tall that they have hit the ceiling. In tests lasting approximately 4 months, the modified poplars increased their weight by 53% compared to control trees without the additional trait, the company reports in a study published today on the bioRxiv server, which does not require formal peer review.
These numbers are “encouraging, but not staggering,” says plant biologist Donald Ort of the University of Illinois, who led the tobacco enhancement program. And he warns that even many promising laboratory results often fall short in more realistic tests. The pampered trees that grow quickly indoors may wilt in more challenging outdoor conditions or may need a lot of water and fertilizer to maintain high growth rates. And once the young trees start to block sunlight, growth often slows down. To test the resilience of Living Carbon’s poplars, Strauss has started cultivating some in a field in Oregon—he hopes to report the results next summer.
Even if field trials prove successful, Living Carbon could face a lengthy regulatory process in order to sell the trees. In the United States, federal regulators have never approved the release of a genetically modified tree designed for rapid growth. The re-evaluation of a chestnut tree engineered to resist a devastating imported blight [a type of fungus] has been ongoing for over 2 years, with no timeline for completion. (The company’s leaders say that a poplar constructed using a different method does not require federal regulatory approval and plan to plant this tree on private land as early as the end of this year).
Meanwhile, some groups oppose the release of any genetically modified trees, fearing unintended ecological consequences. And most programs that certify forest products as sustainable currently ban the use of modified species. This creates “a de facto ban” on their use for consumer products, says Strauss. Taking all issues into account, Ort says that the commercial development of Living Carbon’s trees could be 10 to 15 years away.
Living Carbon may have the resources to withstand such a wait. The company’s leaders say they are backed by nearly $15 million in venture capital funding. And fast-growing trees aren’t the company’s only interest: it’s also trying to engineer trees to absorb heavy metals from degraded soils. The company’s leaders hope these metals could impart antifungal properties to the wood that would slow its rate of decomposition, allowing it to store more carbon.
Strauss, for example, believes that the urgency of addressing the climate crisis outweighs the potential risks associated with genetically modified trees. “We don’t have the luxury,” he says, “to wait 30 years and make sure that nothing can go wrong”…
Source: https://www.science.org/content/article/fight-climate-change-biotech-firm-has-genetically-engineered-very-peppy-poplar
Translation: Harry Tuttle