The American Chestnut Project
Kaitlin M Breda
Administrative Assistant II
322 Illick Hall
Darling 58, the first blight-tolerant, transgenic American chestnut
Founding members of the New York Chapter of The American Chestnut Foundation approached Dr. William Powell and Dr. Charles Maynard of SUNY ESF in 1989, asking them to take a modern approach to develop a blight resistant American chestnut using genetic engineering. Several decades later, we are seeking government approval to begin distribution of the first blight-tolerant transgenic American chestnut. These trees were produced by inserting a gene, oxalate oxidase, also known as OxO, into the American chestnut genome. The gene is found in many plants in the environment and in our diets, including bananas, strawberries, and some mosses and grasses, among others, and it gives these plants the ability to fight fungal infections. It disarms the fungus by breaking down toxins created by the blight fungus. The Darling 58 chestnut uses an OxO gene isolated from wheat.
Before blight-tolerant Darling 58 chestnuts can be distributed in the US, reviews must be completed by three different regulatory agencies. We submitted a "Petition for nonregulated Status" to the USDA-APHIS (read the Executive Summary or the full Petition) in January 2020. Additionally, EPA is reviewing our registration submission regarding environmental safety and interactions with the blight fungus. And finally, because both people and animals use chestnuts as food, the FDA is evaluating our consultation for the nutritional safety of Darling 58. 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). We don't know exactly how long these reviews will take, especially since this is the first time a transgenic forest tree is being considered for restoration use! But a recent notice from the USDA states they tentatively intend to publish a final decision by August 2023, and we expect that a similar timeframe is realistic for the other agencies as well. We are working closely with The American Chestnut Foundation to prepare for distribution of transgenic chestnut seedlings soon!
Frequently Asked Questions
Our 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 our project. It may be several years before our trees are widely available for planting by the general public. If you wish to be added to our notification list so that you can receive updates on the regulatory status of our trees, email firstname.lastname@example.org. Keep an eye out for updates!
In the meantime, we encourage you to plant wild-type (nontransgenic) American chestnuts. Although they are still susceptible to the blight, these are wonderful trees that provide many benefits.
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 our 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. Please visit our Join Us page for more information on how you can participate.
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, on this page https://www.esf.edu/chestnut/poster.htm.
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.
The following fact sheet by The American Chestnut Foundation has information on how to grow American chestnuts, including proper soil conditions and light levels.
The following page from The American Chestnut Foundation has information on identifying American chestnut trees and how to differentiate them from members of other chestnut species. This page also has information on how to submit a leaf and twig sample to determine if your tree is an American 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, 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 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 provided our project with the original funding and supported us through the NY TACF chapter for the next 25 years. The name “Darling” is in honor of his support in initiating the project and his longtime support.
No, people with celiac disease, or other forms of gluten intolerance can eat nuts from Darling 58 chestnuts with no problems. The OxO gene in Darling 58 is also found in many gluten-free grains and other foods (sorghum, rice, bananas, etc.) and is not related to gluten.
- Newhouse AE, Powell WA. Intentional introgression of a blight tolerance transgene to rescue the remnant population of American chestnut. Conservation Science and Practice. 2020;e348. https://conbio.onlinelibrary.wiley.com/doi/pdf/10.1111/csp2.348
- A New Generation Of American Chestnut Trees May Redefine America's Forests, by Ferris Jabr, Scientific American Volume 310, Issue 3
- The American Chestnut's Genetic Rebirth, by William Powell, Scientific American, March 2014 issue, pages 68-73
- Developing Blight-Tolerant American Chestnut Trees(PDF), Powell WA, Newhouse AE, Coffey V. 2019. Developing blight-tolerant American chestnut trees., In Perspectives on Engineering Plants for Agriculture, P. Arnold Editor, Cold Spring Harb Perspect Biol, doi:10.1101/cshperspect.a034587
- 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