About the American Chestnut Tree
The American chestnut was an ecologically, economically, and culturally significant tree species in the eastern United States. In the late 1800s, the introduction of the chestnut blight fungus (Cryphonectria parasitica) from Asia decimated nearly 4 billion American chestnuts. Today, this iconic species rarely reproduces on its own in the wild and is therefore considered functionally extinct.
Rescue and Restoration Efforts
The American Chestnut Foundation (TACF) is leading an unprecedented mission to restore the American chestnut tree to its native range. By employing complementary methods of traditional breeding, biotechnology, and biocontrol, TACF is working to create a disease-tolerant and genetically diverse population of American chestnuts. Working in close collaboration with TACF, the State University of New York College of Environmental Science and Forestry (ESF) leads the biotechnology research and testing efforts. This method has proven to be one of the most successful for generating blight-tolerant American chestnut trees, known as Darling 58, that retain their full complement of traits for adaptation and ecosystem services in our forests. It is imperative, however, that the Darling 58 is bred with wild-type American chestnut trees to diversify the population and provide regional adaptation.
The Transgenic Darling 58 American Chestnut Tree
ESF has developed a revolutionary transgenic American chestnut tree with enhanced blight tolerance: Darling 58. The blight tolerance of the Darling 58 tree is a result of inserting a gene from wheat called oxalate oxidase (OxO). The OxO gene detoxifies the acid produced by fungus and prevents lethal cankers on the tree, essentially allowing the tree to coexist with the blight pathogen. ESF researchers carefully chose the OxO gene because it is well understood, commonly found in nature as a defense against pathogens, and because there has been no evidence that the enzyme is harmful to human or animal health, the environment, or is a plant pest risk. Darling 58 chestnut trees retain 100% of their natural genes, producing the closest form to wild American chestnuts. Read more about the search for blight-resistant genes.
The Future of the American Chestnut Tree
Darling 58 is in the process of undergoing federal deregulation. This process includes the USDA, EPA, and FDA and takes an extensive amount of time. Because genetically engineered plants must be approved for use by federal agencies, ESF has filed a “Petition for Determination of Nonregulated Status for Blight-Tolerant Darling 58 American Chestnut (Castanea dentata)” with the United States Department of Agriculture’s office of Animal and Plant Health Inspection Service (USDA-APHIS). Approval of the petition is a critical step toward planting this blight-tolerant transgenic tree in unrestricted areas as part of restoration programs. We anticipate that new information about the deregulation process will be available in 2023. When that happens, we will share updates iwth TACF members and the public. Nonregulated status will mean that Darling 58 and its offspring can be distributed and planted like wild-type or traditionally bred chestnut trees in unrestricted areas. This would help ensure the survival of the American chestnut by transferring blight tolerance traits to its transgenic offspring, including surviving wild-type trees from across the American chestnut’s native range. Ultimately, this process will safely produce a resilient and diverse population, allowing the tree to thrive and succeed into the future.
Watch a brief video about the project here.
When Will Darling 58 Plant Material Become Available?
TACF is thrilled that its members and the general public are excited about obtaining Darling 58 plant material. It is important to understand that developing and preparing this material for distribution is a process that will take years. Once Darling 58 is deregulated, currently available plant material (pollen) from ESF’s research program will be used to hand-pollinate seed orchards within the native range. These seed orchards will then produce mature trees, which will take a minimum of seven years. Darling 58 pollen that is distributed for other purposes will take place after this effort has been realized and any subsequent plant material in the form of seeds and seedlings will be made available first to our members and then to the public. TACF will need volunteers to help with this herculean effort. We encourage everyone who is excited about Darling 58 to become a member and keep an eye out for opportunities to assist with pollination events.
Darling 58 FAQs
How Darling 58 Got Its Name
The Darling American chestnut was named after Herb Darling, the founder of the New York Chapter of TACF. Herb, along with Stan and Arlene Wirsig, were the people who approached Dr. William Powell and Dr. Charles Maynard, the co-founders of this project, back in 1989 about taking a modern approach to develop a blight-resistant American chestnut tree. Herb Darling was instrumental, providing the project with original funding and supporting ESF through the NY-TACF Chapter for the next 25 years.
Are Darling 58 Hybrids?
No, Darling 58 American chestnuts are not hybrids. They retain all of the American chestnut genes with the addition of one extra gene, OxO, that gives them blight tolerance. Hybrid chestnuts like those produced through The American Chestnut Foundation’s backcross breeding program are a cross between Chinese and American trees. Chestnut trees freely hybridize, and other hybrid varieties exist. Hybrid trees often have traits that are associated with the non-American parent. This can be useful in agricultural and horticultural contexts, but it is not ideal to use hybrid trees for restoration purposes. Because the Darling 58 trees display only American chestnut traits, they are highly suitable for reintroduction into our forests.
Are Darling 58 Trees Safe?
We are continuously studying interactions between our transgenic trees and the environment and potential impacts on ecosystem and human health. A series of articles summarizing various safety tests relevant to the regulatory process were published by The American Chestnut Foundation (read about Nutrition, Wildlife, Plants & Fungi).
How Do I Get A Darling 58 Tree?
Darling 58 American chestnuts are currently undergoing federal regulatory review by the USDA-APHIS, EPA, and FDA. Pending approval, we will distribute our trees for educational purposes, for small-scale restoration, and to the longest supporters of the project. It may be several years before Darling 58 trees are widely available for planting by the general public. In the meantime, we encourage you to plant wild-type (nontransgenic) American chestnuts.
How Can I Help with Darling 58?
There are a few ways that you can support American chestnut conservation and restoration. You can become a member of The American Chestnut Foundation. You can also make a donation to SUNY-ESF’s project to support our research and development. You can also plant wild-type (non-transgenic) American chestnuts and participate in our tree breeding efforts as a citizen scientist.
People with celiac disease or other forms of gluten intolerance can eat nuts from Darling 58 chestnuts safely. The OxO gene in Darling 58 is not related to gluten and is also found in many gluten-free grains and other foods (sorghum, rice, bananas, etc.) that are regularly consumed by celiac patients. ESF used the amino acid sequence (specific arrangement of the protien) to screen against a large database of known toxins and allergens as well as theoretically predicted ones, both resulting in no matches. In addition, Darling 58 chestnuts have been tested by a commercial testing lab for both wheat allergens in general and gluten specifically. Those tests all came back negative.
Darling 58 Resources
- Oxalate Oxidase (OxO)
- Environmental Impact Statement (EIS) for Darling 58
- Plant Pet Risk Assemessment (PPRA) for Darling 58
- SUNY-ESF’s Draft Excerpts from EIS and PPRA
- SUNY-ESF’s About Darling 58/FAQ Page
- Safety Tests on Transgenic American Chestnut, Part 1: Nutrition
- Safety Tests on Transgenic American Chestnut, Part 2: Wildlife
- Safety Tests on Transgenic American Chestnut, Part 3: Plants & Fungi
- Environmental Interactions with Transgenic American Chestnuts Poster
Darling 58 Public Comment Period
- The Transgenic American Chestnut Tree — Darling 58
- Full Petition: Petition for Determination of Non-regulated Status: State University of New York College of Environmental Science and Forestry; Blight-Resistant Darling 58 American Chestnut (APHIS-2020-0030)
- Public Comment Period Frequently Asked Questions
- Public Comment Period Best Practices and Sample Submissions
- Office of Information and Regulatory Affairs – Regulatory Map
This is a dynamic page. Content will be regularly updated between now and potential deregulation. Please check back often.