May 11, 2020

Bring Back the American Chestnut

Using breakthroughs in genetics, scientists are primed to return the long-lost American chestnut tree to the wild, starting this spring.

By Andrew Serazin

Not far from my parents' house is a local thoroughfare called Chestnut Ridge, named so by early settlers to Northeast Ohio for the magnificent trees that characterized Eastern hardwoods. The chestnut tree was once a monumental presence in America: babies were born into chestnut cradles, pastures were bounded by rot-resistant chestnut fences, and funerals laid the faithful departed to rest in straight chestnut coffins. Each spring these trees spread their glory across the canopy of eastern forests. Sadly, a mature American Chestnut hasn’t been seen in these parts for almost a century. During the early part of the 20th century, an invasive fungal blight ripped through the American Chestnut population from Georgia to Southern Canada and killed billions of trees. Now, thanks to new scientific advances, we may soon get to experience another spring among these leafy and productive giants.

After decades of work, a group of scientists at the SUNY College of Environmental Science and Forestry (SUNY-ESF) and the American Chestnut Foundation are poised to finally reintroduce a blight-resistant American Chestnut tree into the wild. The project is backed by a $3.2 million grant from the Templeton World Charity Foundation (TWCF), the largest ever given to the college.

At their peak, the American chestnut tree could grow to over 100 feet high with a 10-foot diameter. In the 19th century, they were attacked by a fungus that caused cankers to form on the trunk, killing off the trees. Scientists at SUNY-ESF are using genetic engineering to create a blight-tolerant tree. Photo courtesy of the American Chestnut Research & Restoration Project.

Restoration of the American chestnut has long been a dream, and for the past fifty years, several different approaches have been attempted to create a blight-resistant tree. One pioneer researcher, Dr. William Powell, knew that blight resistance was possible, since Asian varieties of the tree are naturally resistant to the blight. Yet the American Chestnut tree is unique in its massive size and ability to reach into the upper canopy of forests, and attempts to hybridize it with Asian varieties did not yield sufficiently tall trees. Conventional cross-breeding approaches also have failed to confer blight resistance. Turning to more precise genetic methods, the team at SUNY-ESF inserted a single gene (taken from wheat) which inactivates the fungal toxin, rendering the blight harmless to the tree. The team not only found that the genetically modified trees, a variety known as Darling 58, could withstand the blight, but that the modified trees were compatible with the larger ecosystem.

The project is now embarking on a critical phase. Formal dossiers have been submitted to US regulatory agencies USDA, FDA, and EPA and the public can now comment on the project. If approved, this would be a breakthrough on multiple levels. Of course, there is the purely scientific achievement of creating a blight-resistant tree. But it also represents the first time genetic engineering has been used to reintroduce a species to the wild. And thanks to SUNY-ESF’s decision not to patent the genetic modification and the broad-based partnership with the American Chestnut Foundation, it also represents a historic opportunity to demonstrate how genetic technologies can be used for public benefit without the complications of commercial interest that typify the uses of genetic engineering technology.

For many years, the debate over GMOs has cleaved roughly between an expert scientific community — which sees them as technological achievements that must be employed to optimize efficiency and productivity in agriculture — and an environmental community that views them as vehicles to perpetuate the aggressive business practices of large corporate interests. The reality is that, at least in some cases, both sides may be right. Technological achievements like genetic engineering can serve to reaggravate age-old imbalances in power. But at the same time, these technologies can and must be deployed to address a host of societal concerns.

My hope is that the example of the American chestnut will provide a chance to change the nature of the debate around GMOs for the better.

Hand pollination of a chestnut tree done by the American Chestnut Research & Restoration Project. Photo courtesy of Hannah Pilkey.

This is why I am so enthusiastic in my support for the project; not only does it advance science, but it also helps to advance a more sophisticated and effective conversation about the role of genetic technology in society. The project is pursuing a new regulatory paradigm requiring approval from the FDA, USDA, and EPA after conducting dozens of safety tests. For example, modified chestnut leaves are being fed to tadpoles to assess whether these frogs-to-be develop correctly. So far, so good. The process is robust — as it should be — but if all these tests show fundamental safety and efficacy, it will be revolutionary for our forests.

The spiny burr and three nuts from an American chestnut tree. Photo courtesy of Andy Newhouse.

Once approved, widespread planting of the new American Chestnut can commence almost immediately. Within our lifetimes we once again may get to experience the United States as it was for thousands of years before the modern era. With the restoration of the American Chestnut, each fall will produce a bounty of nuts, and each spring will bring new buds and green leaves on titans of the forest. To me, this is a welcome vision of renewal in the midst of our current global struggles.