Since long before the first settlers arrived in North America until the mid-1950s, there were billions of American chestnut trees (Castanea dentata) blanketing the forests from Maine to Florida.1 The deciduous trees could grow more than 100 feet tall and span 9 feet around. In fact, a lone chestnut estimated at 100 years old, was discovered in Maine in 2015, measuring out to a towering 115 feet tall.2
Although majestic to see, the trees also produced edible nuts that could be ground into flour, stewed into puddings or roasted and eaten out of the shell. Early Native Americans used the leaves for medicinal treatments and the wood was the first choice for pioneer log cabins.
Many times, the first 50 feet of the trunk was clean, without branches or knots, making it a builder’s dream.3 The trees grow fast and did not rot, so were a good choice for telephone poles and railroad ties.
The New York Times reports that in 1915, one author estimated it was the “single-most-cut tree” in America. As North America was settled, the American chestnut trees were the basis of Appalachian subsistence farming. New York Times reports that in 2005, historian Donald Davis wrote:4
“With the death of the chestnut, an entire world did die, eliminating subsistence practices that had been viable in the Appalachian Mountains for more than four centuries.”
The American chestnut tree also provided food for animals in the forest, including deer, squirrels and bears.5 Unlike oak trees with irregular acorn cycles,6 chestnut trees produce every year. Local farmers would send their hogs and cattle to forage on the chestnuts that had ripened and fallen to the ground in the late fall.7
Chestnut Blight Reduced Majestic Trees to Shrubs
Near the turn of the 20th century, a fungus that has all but eradicated the mature American chestnut trees was introduced into the U.S. through infected, imported nursery stock from China.8,9 The U.S. Department of Agriculture National Invasive Species Information Center reports the blight was identified for the first time on dying chestnut trees in the Bronx Zoo.
The fungus was named Cryphonectria parasitica and may have arrived as early as 1893.10 It wasn’t long afterward that states began reporting dying American chestnut trees.11 Currently, the trees are so rare that discovery of an American chestnut tree in the wild rates a report in the national press.
However, as The American Chestnut Foundation reports, the tree has not gone completely extinct but, rather, is considered “functionally extinct” since the fungus does not affect the root system.12 The American chestnut is highly susceptible to the fungus as is the European chestnut. But the Chinese chestnut tree has some resistance to the infection as it causes only a small canker in the bark.13
The fungus is an ascomycete,14 also known as sac fungi since it has a sac-like structure with four to eight ascospores in the sexual stage. Some of the largest and more commonly known ascomycetes are morel mushrooms and truffles. Other pathogens in the same group include those that cause Dutch elm disease and apple scab.15
The fungus can infect a tree through small injuries to the bark, some as small as those created by insects.16 The fungus then grows under the bark and produces yellow-brown blisters. The infection eventually makes its way around the trunk, cutting off nutrients and water.17
The infection is called a blight, potentially because the branches die quickly. However, the fungus can infect branches, stems and a trunk of any size. It grows rapidly and continues to grow after the tree has died.18
Since the disease does not affect the roots of the tree, the species continues to survive by sending up sprouts through the stump. Inevitably, however, they succumb to the disease. Yet, a USDA Forest Service survey found there may be 60 million of these sprouts growing in the forests of New York state.19
How Genetically Engineered Chestnut Trees Were Birthed
Although the U.S. has lost other plants and animals to extinction, the American chestnut tree appears to have an emotional hook that has driven some to produce a genetic modification in the hope of bringing back large stands of the trees. The New York Times reports this may have started in 1989 when Herb Darling received a call telling him of an American chestnut tree on his property.20
The tree was five stories high and about two feet wide, but also was dying from the fungal disease. Unable to save the tree, he decided to save the seeds. But since the tree wasn’t making any, he went about finding a male tree to fertilize the flowers in the spring.
After one failed attempt to fertilize the flowers, the tree produced about 100 nuts. He planted some and sent the others to Charles Maynard and William Powell, tree geneticists from State University of New York College of Environmental Science and Forestry. Thus began the movement to engineer a new American chestnut tree that might be resistant to the blight.
Although the intent may be rooted in the desire to see these trees begin to repopulate the forests, ultimately the results may be disastrous. Initially, Darling looked for support from The American Chestnut Foundation, but the group was wary of genetic engineering.
The first attempt at inserting an antimicrobial compound into the tree genes originated from frogs. After several years, this was abandoned when the team feared the public would have problems with a tree containing amphibian genetics. The next step was to look for a single resistance gene in the Chinese chestnut tree that didn’t have trouble with the fungus.
However, as the scientists discovered, the Chinese chestnut tree is a complex organism that uses multiple genes to protect against the blight.21 In 1997, Powell found a scientific paper describing how the insertion of one gene from wheat expressed oxalate oxidase that protected a plant against oxalate-producing fungus, which the chestnut fungus produced.
Scientists Frustrated by Regulations to Protect the Forest
In 2013, the team announced their success in creating a version of the American chestnut tree that could defend against Cryphonectria parasitica.22 Each successive iteration of the tree has been named after Darling. This one is the Darling 58.
In 2018, Powell spoke at a chapter meeting of The American Chestnut Foundation to talk about his three-decadeslong research project. He warned the attendees that as many of the technical obstacles of producing a transgenic tree resistant to Chestnut blight had been overcome, they now face their biggest challenge: approval to plant a transgenic tree in the wild.
The approval process began with a 3,000-page report to the branch at the USDA responsible for regulating genetically engineered plants. The team also plans to file petitions so the FDA can examine the food safety of the nuts and with the EPA to review the impact the tree may have under Federal pesticide law. The New York Times reported a conversation during the meeting:23
“‘This is more complicated than science!’ someone in the audience said. ‘It is,’ Powell agreed. ‘Science is fun. This is frustrating.’ (‘Being regulated by three different agencies is kind of overkill,’ he told me later. ‘That really stifles innovation in environmental conservation.’)”
It is crucial to remember that releasing genetically engineered organisms into the wild comes with a risk. While researchers may be frustrated by the regulations, without at least the minimal oversight now in effect, the food supply could be sorely impacted.
As it is, there is a significant percentage of the foods you purchase at the grocery store that contain some form of genetically engineered ingredients. The Center for Food Safety lists potential unexpected health risks that may be posed by genetically altering human and animal food. These include:24
- Allergic reactions
- Antibiotic resistance
- Immunosuppression and cancer
- Lack of nutrition
Scientists Have Not Identified the Impact of GE Trees
However, while the scientists told The New York Times they plan to submit a report to the FDA for judgment about food safety of the chestnuts, Gary Ruskin, co-director of US Right to Know, writes that the FDA has repeatedly made it clear that they do not test whether genetically engineered foods are safe.25
“As Jason Dietz, a policy analyst at FDA explains about genetically engineered food: ‘It’s the manufacturer’s responsibility to insure that the product is safe.’ Or, as FDA spokesperson Theresa Eisenman said, ‘it is the manufacturer’s responsibility to ensure that the [GMO] food products it offers for sale are safe …’”
In a white paper produced by The Campaign to STOP GE Trees, Biofuelwatch and Global Justice Ecology Project, they propose the GE American chestnut tree is a test case to determine if the public will “support biotechnology for forest conservation,” paving the way for more GE trees. They quote geneticist David Suzuki, who says:26
“We’re still at the very beginning of understanding what we’re doing. The rush to apply these [genetic engineering] ideas is absolutely dangerous, because we don’t have a clue what the long-term impacts of our manipulations are going to be.”
As Powell and Maynard push forward with the current support of The American Chestnut Foundation and others interested in populating the forest with genetically engineered trees, The Campaign to STOP GE Trees brings to light many of the questions regarding safety and the future of the environment that have not been addressed.27
“Locating and monitoring the progress of all the GE AC trees and their progeny will be near impossible, especially over a long period of time. There has been some discussion of planting the GE trees slowly, in stages, to improve the potential for monitoring. However, common sense and past experience with genetically engineered crops suggests that monitoring is not feasible.
A release of GE AC trees into natural forests raises some important questions and concerns about potential risks. For example: Will the nuts from GE AC be safe to eat? Will GE AC be safe for soils, waterways, fungi, pollinators, and other animal and plant species in the forest ecosystems where they grow?
Will inhaling pollen from GE chestnut be harmful? Will introducing GE AC present risks to the few remaining native AC trees, or those in hybrid backcross breeding program orchards?
Bees, butterflies, squirrels, birds and humans can carry away tree nuts and pollen, and pollen can also be blown on the wind. Once the engineered trees are released into forests, the GE AC ‘experiment’ will be irreversible. There is no way to prevent the trees from spreading, including across cultural or jurisdictional boundaries.
Before we can evaluate the risks, we must first ask: do we have the tools, information, time and wisdom to conduct adequate risk assessments? Only then can we determine whether the risks are worth taking.”
Biotechnology May Derail Natural Initiatives
Anne Petermann wrote in the Scranton Times-Tribune that planting these genetically altered trees opens the door for other risky genetically engineered plants. The fact is a wild tree cannot be replaced by a genetically altered facsimile. Peterman says this is “not restoration, but an uncontrolled experiment with our forests.”28
It is impossible to have the American chestnut trees in numbers that were living in the early 1900s. However, there are other areas of research currently underway to help the species recover. The first is breeding for resistance. Researchers have experimented with crossbreeding Chinese chestnut trees with the American chestnut.29
However, the Chinese chestnut is much shorter and spreads wide instead of going tall and straight. While the process has been slow, The American Chestnut Foundation has had some success in developing a hybrid that is 15/16 American chestnut with selection for resistance and form. They are boosting seed production of a line of trees that appear to be blight-resistant to plant at test sites.
Another line of research has been aimed at lowering the virulence of the fungi. Experiments with infected European chestnut trees show the fungi had developed hypovirulence or had become less toxic to the trees. Researchers found double-stranded RNA within the fungi they later discovered was a virus. The virus caused the fungus to become less virulent.
This treatment has shown some promise in Europe and Michigan. Unfortunately, it has not had the same success along the eastern shores of North America. Researchers have been able to therapeutically treat individual infections, but using this strategy at a population level depends on nature. Petermann believes the genetically altered trees threaten to derail the reintroduction of natural trees.30
“Because the GE chestnuts were developed in a lab in a way that could never occur in nature (forcing genes from unrelated wheat plants into the DNA of trees), there is no way to know how they will respond in nature.
In fact, the researchers who promote these trees have done no long-term risk assessments to determine how these trees will interact in a natural forest over time, or how they will impact human health.”
The petition to deregulate the Darling 58 American Chestnut tree was submitted to the USDA January 17, 2020.31 The Campaign to STOP GE Trees developed several talking point samples to be used when the Animal and Plant Health Inspection Service was accepting comments.32 The deadline for public comments was October 19, 2020. At this time the USDA is reviewing the comments before making their ruling.