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In mid-February, Living Carbon, a company, planted five thousand genetically modified poplar seedlings on the edge of a forest in the US state of Georgia. Reporters and ecologists state that this is an unprecedented case where a private company obtained permission to grow GM plants in record time, even though there are no scientific publications that confirm the trees can solve the problem for which they were developed.
The creators claim that the new variety of poplar trees exhibits more efficient photosynthesis, which theoretically enables them to grow one and a half times faster than wild relatives. The company’s founders intend to combat the rise in atmospheric CO₂ concentration and, consequently, climate change by planting several million similar seedlings within a year.
Living Carbon’s genetic engineers utilized an invention by synthetic biologists from the University of Illinois to achieve accelerated tree growth. They introduced a pair of enzymes from Chlamydomonas algae in one case, and from pumpkin in the other, into the plant cells of tobacco to “boost” the rate of atmospheric carbon fixation. The GM plant in the experiment demonstrated significantly improved photosynthesis, gaining weight 25% faster and having 40% more starch (which serves as an energy reserve) in its cells due to the intervention.
Scientists have decided to use a small “GM update” to correct one of the “bugs” of evolution, as not all plants are ideal machines for photosynthesis.
It is a well-known fact that plants create their biomass from sunlight and air, specifically from carbon dioxide, which is transformed into sugars using a specialized enzyme and the energy of the sun. However, less known is that not all plants perform this process in the most optimal way despite millions of years of evolution.
The efficiency of carbon dioxide fixation by most plants is limited by a fundamental problem – the enzyme responsible for attaching a CO₂ molecule to the “template” of the future sugar molecule can mistakenly attach an “incorrect” oxygen instead of the “correct” carbon. This side reaction results in the formation of glycolate, which exits the chloroplasts (where photosynthesis occurs) and eventually decomposes, releasing a molecule of CO₂. Therefore, due to the enzyme’s mistake, the plant loses carbon rather than fixing it, a process known as photorespiration.
Some plants, such as corn, have adopted complex additional methods (such as C4 photosynthesis) to partially bypass the inefficient process of photorespiration. However, genetic engineers from Illinois have proposed a simpler and more elegant solution, which prevented the release of glycolate from chloroplasts by cleaving carbon from it, enabling the fixing enzyme to attach it to the “template” of sugar and largely suppress photorespiration. By conducting experiments on tobacco, they successfully identified a combination of genes for the corresponding enzymes, which they plan to utilize at Living Carbon to optimize photosynthesis in poplar.
Living Carbon’s decision to shortcut the long path from a scientific article to alleys with GM poplars may result in questionable outcomes.
The issue is that trees have significant differences from tobacco, making the impact of the same modification on a different organism uncertain and unpredictable. While the company’s researchers conducted experiments to assess the outcome, the results were published as a preprint on the bioRxiv website, indicating that the manuscript had not been peer-reviewed by other scientists and had not been officially published at the time of approval.
The company Living Carbon only tested the trees in a greenhouse before releasing them into their natural habitat. The greenhouse tests yielded promising results concerning the growth rate of the trees. However, the company did not conduct any field trials before proceeding with large-scale planting. Despite this lack of testing, representatives of Living Carbon managed to secure permission for the tree planting in record time. This development surprised not only the environmental organization The Global Justice Ecology Project, which opposes the planting of GM trees, but also Living Carbon’s closest “competitors” – a group of scientists who had been waiting for permission to grow an American chestnut resistant to fungus for three years.
According to The New York Times, the founders of Living Carbon utilized a loophole in the legislation that enabled them to sidestep regulation by federal authorities (USDA). They accomplished this by utilizing a relatively rudimentary method for genetically modifying their plants, which, legally speaking, did not classify their plants as “modified.”
In 2020, an amendment to agricultural legislation stipulated that only genetically modified plants obtained via a bacterial or viral vector, where bacteria or viruses function as carriers of new genetic information, are subject to USDA regulation. This method of genetic modification is currently the most commonly used in plant laboratories. To accomplish this, scientists utilize agrobacteria, which possess a natural capacity to penetrate plant cells and transfer their DNA, that have been outfitted with a newly created DNA construct. In this way, the desired gene is initially introduced into the bacteria, which then infect the plant cells.
While conducting experimental trials on poplars, the engineers at Living Carbon also employed this established method of genetic modification. However, the seedlings that ended up in the state of Georgia were produced using an entirely different method that, according to US legislation, does not qualify as genetic modification. The method in question involves the use of a “gene gun” – a process that entails shooting microscopic gold particles coated with genetic material into plant cells. This method is also well-known and quite dependable, but it has a significant drawback: the desired genes can be integrated into any part of the genome due to the “shooting” process. From a formal and physiological perspective, the plants obtained using the gene gun method differ from the seedlings obtained using agrobacteria, which demonstrated a 50% increase in biomass growth compared to the original poplars in the preprint.
Living Carbon suggests that companies that emit greenhouse gases should compensate for their emissions by paying for the planting of GM poplar trees, which they refer to as “climate indulgences.
Maddy Hall, who previously worked on projects like OpenAI in Silicon Valley, currently serves as the CEO and co-founder of Living Carbon. Since its inception three years ago, the company has received more than $36 million in venture capital and investments. However, given that poplar trees cannot be consumed and their wood is not especially valuable, one might wonder how the company intends to generate revenue.
Living Carbon intends to trade “carbon credits,” which are quotas on greenhouse gas emissions expressed in tons of carbon dioxide. In essence, the company’s founders will provide businesses the chance to purchase permission to emit a specific quantity of CO2 and, in exchange, pledge to plant a specific number of fast-growing poplar trees that will rapidly absorb CO2 from the atmosphere within a few years.
The success of this concept appears to be reasonable if the poplar trees indeed prove to be effective, as their efficacy is yet to be fully demonstrated. Nonetheless, Living Carbon’s business model faces other challenges besides the viability of the project rationale.
Apart from environmentalists’ discontent, who criticize such a strategy as “indulgence trading” that simply creates the impression of combating climate change, the primary concern is the potential for “leakage” of new genes into the environment through crossbreeding between GM plants and their original counterparts.
Moreover, any modification that enables faster growth or immunity to pests unquestionably provides an evolutionary edge to the species, allowing it to expand more rapidly than the wild type. For this reason, environmentalists associated with organizations such as The Global Justice Ecology Project oppose planting GM trees as they believe (perhaps with justification) that “enhanced” strains can easily outcompete all other trees, posing a threat to biodiversity.
The US has been using targeted genetic modifications to enhance plant properties rather than traditional breeding, which is not a new practice. Currently, around 90% of the corn, soybean, and cotton cultivated by US farmers are genetically modified varieties that offer resistance to pesticides and pests. Besides the primary agricultural crops and a few other plant species mainly utilized for livestock feed, GM trees are also present in the country. These trees are resistant to papaya and apple viruses and yield apples that do not darken over time when exposed to air, i.e., if an apple is sliced, it won’t turn brown.
China has been cultivating GM poplar trees for more than 20 years. In 2002, the Chinese Ministry of Agriculture sanctioned the use of two strains of these trees for commercial purposes. These strains contained genes from bacterial toxins, which were intended to make the plants resistant to pests. To counteract the desertification of their land, China is currently undertaking extensive planting of poplars. Poplar wood is also utilized for technical applications such as producing paper and plywood.
Chinese scientists conducted a scientific review in 2018 that summarized the results of many years of research and cultivation of GM poplar trees. According to field trials, the growth of “toxic” trees did not significantly affect the structure of soil microbial communities. However, regarding repelling insects, it appears that the number of pests has not decreased where these trees grow. This could be due to pests feeding on neighboring trees or developing resistance to the toxin, or GM trees not performing as well in the wild as they did in the laboratory. Since then, China has developed at least 22 more strains of poplar trees. However, authorities are not in a rush to permit their release into forests.
The USA has already experienced a high-profile project with questionable justification in the biotech sector, such as Elizabeth Holmes’ Theranos. Nevertheless, the outcome of GM poplar tests still has the potential to disprove skeptics.
Living Carbon’s founders recognize certain environmental hazards, hence they have opted to grow GM poplar trees alongside conventional ones in a pilot plantation in Georgia. This approach also provides an opportunity for a scientific experiment to verify whether GM trees have the purported properties. All GM poplar trees planted in the plot are female, and thus do not produce pollen. In addition to poplars, various other species will be cultivated on the site to evaluate the effect of GM trees on biodiversity.
The farm owner where the pilot plantation is situated has no objections to GM trees. The land was previously unused, and now he will receive rent and some technical timber, even in the worst-case scenario. The company intends to utilize swamps and abandoned mines for planting, all of which are on private property.
Although there is a clear lack of transparency in the project, Living Carbon has a scientific partner in the form of the University of Oregon. However, even employees of the university express healthy skepticism about the potential success of the idea. Scientists are primarily concerned about the absence of field trial data as outcomes obtained in a laboratory greenhouse may differ considerably from those obtained in the field. Additionally, the author of the study published in Science, which the company relied upon to enhance trees, is not completely confident in its effectiveness. There is also a possibility that the poplars may not grow quickly enough.
It seems that the primary “threat” associated with the new GM poplar variety is unmet expectations. This is similar to what occurred a few years ago when the founder of the biotech startup Theranos made promises of revolutionizing blood tests without any concrete results from her developments. That story culminated in court and prison sentences. However, Living Carbon is not guaranteeing instantaneous outcomes, as engineers have several years to refine imperfect technologies while the poplars grow.
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