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The American Chestnut Project

History of Darling American chestnut

Founding members of the New York Chapter of The American Chestnut Foundation approached Dr. William Powell and Dr. Charles Maynard of ESF in 1989, asking them about using modern tools of genetic engineering to develop a blight tolerant American chestnuts. Several decades later, we are seeking government approval to begin distributing the first blight-tolerant transgenic American chestnut. These trees were produced by inserting a gene called oxalate oxidase (OxO) into the American chestnut genome. This gene, found in many plants in the environment such as bananas, strawberries, and some mosses and grasses, gives these plants the ability to fight fungal infections. It protects the tree by breaking down a toxin created by the blight fungus. The OxO gene in Darling chestnuts was isolated from wheat, however, it is gluten-free.

A man taking care of chestnut saplings

Frequently Asked Questions

Our Darling American chestnuts are currently undergoing federal regulatory review by the USDA-APHIS, EPA, and FDA. Pending approval, we aim to distribute our trees for educational purposes, for small-scale restoration trials, and to the longest supporters of our project. It may be several years before our trees are widely available for planting outside of focused research efforts. If you wish to be added to our notification list so that you can receive updates on the regulatory status of our trees, email Keep an eye out for updates!

In the meantime, we encourage you to plant wild-type (non-transgenic) American chestnuts. Although they are still susceptible to the blight, these are wonderful trees that provide many benefits and may eventually be used to cross-pollinate with blight-tolerant chestnuts.

There are a few ways that you can support American chestnut conservation and restoration. You can make a tax-deductible donation to ESF to support research and development by the chestnut project. You can also plant wild-type (non-transgenic) American chestnuts and participate in our tree breeding efforts as a citizen scientist. This Facebook group offers a chance to interact with other enthusiasts and follow updates from our team. Please visit our Join Us page for more information on how you can participate.

Yes! Numerous studies on a variety of organisms and environmental interactions confirm safety of Darling and other transgenic chestnuts with OxO. 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). You can read more about our environmental interaction studies, including an informational poster outlining our findings.

No, Darling American chestnuts are not hybrids. Hybrid trees have a blended genome from two related species, such as American chestnut and Chinese chestnut. In contrast, Darling trees 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, and some traits may have adaptive benefits,  but primarily American chestnut traits are desirable for restoration purposes. Because the Darling trees display only American chestnut traits, they are appropriate highly suitable for reintroduction into our forests.

The following fact sheet by The American Chestnut Foundation has information on how to grow American chestnuts, including proper soil conditions and light levels.

Growing Chestnut Fact Sheet

A variety of chestnut species and hybrids are widespread throughout the eastern US, and positive identification can be difficult even for experts as traits can vary due to several factors. Relative to other chestnut species, American chestnuts (Castanea dentata) tend to have longer leaves with prominently hooked teeth, skinnier twigs, hairless leaves & twigs, smaller nuts, and a narrower and more upright tree form. Other North American chestnut relatives called chinquapins (C. pumila & C. ozarkensis) are distinguished by a single nut per bur, while most other chestnuts typically have three or more nuts per bur. American chestnuts are commonly confused with American beech, chestnut oak, and horse chestnut.

We also encourage you to submit observations of American chestnuts to the apps TreeSnap and iNaturalist, which are used by scientists and conservationists to aid in efforts to observe and conserve the American chestnut and other species.

The Darling American chestnut was named after Herb Darling, an original 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 our project, back in 1989 about taking a modern approach to develop a blight resistant American chestnut tree. Herb Darling was instrumental in starting our project. He and the New York Chapter provided our project with the original funding and supported us continually ever since. The name “Darling” is in honor of Herb's support in initiating the project and unwavering dedication to our shared goal of American chestnut restoration.

No, people with celiac disease, or other forms of gluten intolerance can eat nuts from Darling chestnuts with no problems. The OxO gene in Darling chestnuts is also found in many gluten-free grains and other foods (sorghum, rice, bananas, etc.) and is not related to gluten. This was carefully studied and described in regulatory documents; see Section 11.5 (p. 192) of our Petition to the USDA for more details.

Suggested Readings

Overview articles

Research articles

  • Onwumelu, A., Powell, W.A., Newhouse, A.E., Evans, G., Hiles, G., Matthews, D.F., Coffey, V.C., and Drake, J.E. 2022. Oxalate oxidase transgene expression in American chestnut leaves has little effect on photosynthetic or respiratory physiology. New Forests.
  • Newhouse, Andrew E., Anastasia E. Allwine, Allison D. Oakes, Dakota F. Matthews, Scott H. McArt, and William A. Powell. 2021. Bumble Bee (Bombus impatiens) Survival, Pollen Usage, and Reproduction Are Not Affected by Oxalate Oxidase at Realistic Concentrations in American Chestnut (Castanea dentata) Pollen. Transgenic Research 30:751-764.
  • Brister, E., and A.E. Newhouse. 2020. Not the same old chestnut: Rewilding forests with biotechnology. Environmental Ethics 42:149-167.
  • Brown, A.J., Newhouse, A.E., Powell, W.A., and Parry, D. 2020. Comparative efficacy of Gypsy moth (Lepidoptera: Erebidae) entomopathogens on transgenic blight-tolerant and wild-type American, Chinese, and hybrid chestnuts. Insect Science 27:1067-1078.
  • Westbrook, J.W., Holliday, J.A., Newhouse, A.E., and Powell, W.A. (2020). A plan to diversify a transgenic blight-tolerant American chestnut population using citizen science. Plants, People, Planet 2, 84-95.
  • Goldspiel, Harrison, Andrew E. Newhouse, James P. Gibbs, and William A. Powell. 2018. "Effects of Transgenic American Chestnut Leaf Litter on Growth and Survival of Wood Frog Larvae." Restoration Ecology 27:371-378.
  • Newhouse, A.E., Oakes, A.D., Pilkey, H.C., Roden, H.E., Horton, T.R., and Powell, W.A. (2018).Transgenic American Chestnuts Do Not Inhibit Germination of Native Seeds or Colonization of Mycorrhizal Fungi.
    Frontiers in Plant Science 9:1–9.
  • Newhouse, AE, LD McGuigan, KA Baier, KE Valletta, WH Rottmann, TJ Tschaplinski, CA Maynard, WA Powell. 2014. Transgenic American chestnuts show enhanced blight resistance and transmit the trait to T1 progeny. Plant Science 228:88-97
  • Zhang B, AD Oakes, AE Newhouse, KM Baier, CA Maynard and WA Powell. 2013. A threshold level of oxalate oxidase transgene expression reduces Cryphonectria parasitica- induced necrosis in a transgenic American chestnut (Castanea dentata) leaf bioassay. Transgenic Research 22:973-982.
  • Newhouse, AE, JE Spitzer, CA Maynard, WA Powell. 2014. Leaf Inoculation Assay as a Rapid Predictor of Chestnut Blight Susceptibility. Plant Disease 98:4-9
  • Baier, K.M., C.A. Maynard, and W.A. Powell. 2012. Early flowering in Chestnut species induced under high intensity, high dose light in growth chambers. Journal of The American Chestnut Foundation 26:8-10
  • D'Amico, T. Horton, C. Maynard, and W. Powell. 2011. Assessing ectomycorrhizal associations and transgene expression in transgenic Castanea dentata. (Extended abstract for the IUFRO meeting in 2011) BioMed Central (BMC) Proceedings 2011, 5(Suppl 7):O54
  • Powell's publications