American chestnut

American chestnut
American chestnut leaves and nuts

Vulnerable  (NatureServe)[2]
Scientific classification Edit this classification
Kingdom: Plantae
Clade: Tracheophytes
Clade: Angiosperms
Clade: Eudicots
Clade: Rosids
Order: Fagales
Family: Fagaceae
Genus: Castanea
Species:
C. dentata
Binomial name
Castanea dentata
(Marsh.) Borkh.
Natural range of Castanea dentata

The American chestnut (Castanea dentata) is a large, fast-growing deciduous tree of the beech family native to eastern North America.[3] As is true of all species in the genus Castanea, the American chestnut produces burred fruit with edible nuts. The American chestnut was once one of the most important forest trees throughout its range,[4][5] however, claims that it was one of the numerically dominant tree species in pre-settlement eastern forests are unsubstantiated.[6]

During the early to mid-20th century, American chestnut trees were devastated by chestnut blight, a fungal disease that came from Japanese chestnut trees that were introduced into North America from Japan.[7] It is estimated that the blight killed between three and four billion American chestnut trees in the first half of the 20th century, beginning in 1904.[8][9][10] Few mature American chestnuts exist within its former range, although many stumps and root systems continue to send up saplings. Most of these saplings get infected by chestnut blight, which girdles and kills them before they attain maturity. There are hundreds of large (2 to 5 ft (0.6 to 1.5 m) in diameter) American chestnuts outside its historical range, some in areas where less virulent strains of the pathogen are more common, such as the 600 to 800 large trees in Northern Michigan.[11][12] The species is listed as endangered in Canada under the Species at Risk Act.[13] American chestnuts are also susceptible to ink disease, particularly in the southern part of its native range; this likely contributed to the devastation of the species.

Several groups are attempting to create blight-resistant American chestnuts. Scientists at the SUNY College of Environmental Science and Forestry created the Darling 58 cultivar of American chestnut by inserting the oxalate oxidase gene from wheat into the genome of an American chestnut.[14] When expressed in the vascular cambium of the Darling 58 cultivar, the oxalate oxidase enzyme degrades the oxalic acid produced by the chestnut blight, reducing damage to the vascular cambium and resisting girdling of the trunk. As of 2021, the researchers who developed this cultivar are working toward applying for government permission to make these trees available to the public. If approved, these chestnut trees would be the first genetically modified forest trees released into the wild in the United States.[15] Alternate approaches to developing a blight-resistant cultivar include cross-breeding among partially blight-resistant American chestnuts or crossbreeding with the moderately blight-resistant Chinese chestnut, then backcrossing with the American chestnut, with the goal of retaining most of its genes.[16][17][18][19]

  1. ^ Stritch, L. (2018). "Castanea dentata". IUCN Red List of Threatened Species. 2018: e.T62004455A62004469. doi:10.2305/IUCN.UK.2018-1.RLTS.T62004455A62004469.en. Retrieved November 15, 2022.
  2. ^ "NatureServe Explorer 2.0". explorer.natureserve.org. Retrieved November 15, 2022.
  3. ^ Nixon, Kevin C. (1997). "Castanea dentata". In Flora of North America Editorial Committee (ed.). Flora of North America North of Mexico (FNA). Vol. 3. New York and Oxford: Oxford University Press. Retrieved September 26, 2015 – via eFloras.org, Missouri Botanical Garden, St. Louis, MO & Harvard University Herbaria, Cambridge, MA.
  4. ^ Davis, Donald E. (2005). "Historical Significance of American Chestnut on Appalachian Culture and Ecology". ecosystem.psu.edu. Retrieved October 28, 2015.
  5. ^ Elliott, Katherine J.; Swank, Wayne T. (August 1, 2008). "Long-term changes in forest composition and diversity following early logging (1919–1923) and the decline of American chestnut (Castanea dentata)". Plant Ecology. 197 (2): 155–172. Bibcode:2008PlEco.197..155E. doi:10.1007/s11258-007-9352-3. ISSN 1573-5052. S2CID 16357358.
  6. ^ Edward K. Faison and David R. Foster: "Did American Chestnut Really Dominate the Eastern Forest?"
  7. ^ Powell, George Harold (1898). The European and Japanese chestnuts in the eastern United States. No. 42. Newark, Delaware: Delaware College Agricultural Experiment Station.
  8. ^ Griffin, Gary. "Recent advances in research and management of chestnut blight on American chestnut". Phytopathology 98:S7. www.apsnet.org, 2008. Retrieved January 12, 2016.
  9. ^ Cite error: The named reference sam was invoked but never defined (see the help page).
  10. ^ Hebard, F.V. "The American Chestnut Foundation Breeding Program". www.fs.fed.gov. Retrieved January 15, 2016.
  11. ^ Brewer, L. G. (1982). "The present status and future prospect for the American chestnut in Michigan". Michigan Botanist. 21: 117–128.
  12. ^ Fulbright, D. W.; Weidlich, W. H.; Haufler, K. Z.; Thomas, C. S.; Paul, C. P. (December 1983). "Chestnut blight and recovering American chestnut trees in Michigan". Canadian Journal of Botany. 61 (12): 3164–3171. doi:10.1139/b83-354.
  13. ^ "American Chestnut (Castanea dentata)". Species at Risk Public Registry. Government of Canada. December 12, 2023. Retrieved May 10, 2024.
  14. ^ Newhouse, Andrew E.; Powell, William A. (April 2021). "Intentional introgression of a blight tolerance transgene to rescue the remnant population of American chestnut". Conservation Science and Practice. 3 (4). Bibcode:2021ConSP...3E.348N. doi:10.1111/csp2.348.
  15. ^ "Record details".
  16. ^ Rea, Glen. "Blight Resistance" (PDF). Journal of American Chestnut Foundation.
  17. ^ "Tree Breeding". The American Chestnut Foundation. Retrieved April 27, 2020.
  18. ^ "American chestnut rescue will succeed, but slower than expected | Penn State University". news.psu.edu. Retrieved April 27, 2020.
  19. ^ Jackson, Teresa; Affairs, SRS Public. "Testing Blight Resistance in American Chestnuts". CompassLive. Retrieved April 27, 2020.