American Chestnut Recovery

1. American Chestnut Recovery Student’s name Institution affiliation Course code and name Date

2. Introduction • For years, the American chestnut (Castanea dentata) was considered as one of the most important forest trees in the United States (Powell et al., 2015). • However, mature American Chestnuts have virtually become extinct that has driven bodies such as the  American Chestnut Foundation to come up with initiatives for restoring the trees. • The extinction of this species of trees was mainly contributed by Chestnut blight that was a fungal disease that emanated from East Asia. • It is estimated that in the first half of 20th century approximately 3 to b billion American Chestnut trees were destroyed by the virus rendering the trees as an endangered species in the United States and Canada. • Today, efforts are being made to create blight resistance Chestnut trees that is geared towards the restoration of the species. • In this regard, feedback in provided on the Chestnut blight infestation and on the restoration of the trees through genetic engineering and hybridization.

3. Chestnut blight Infestation • Prior to the Infestation of the fungal blight, Cryphonectriaparasiticain the American Chestnut trees, this species of trees were considered as perfect trees. • The trees were known for their good qualities such as massive size, rot-resistant, and even fast growth. • It was easy to mill the trees into any form on furniture, cabin logs, and fence posts among other useful forms. • However, the dominance did not last beyond 1904 when a forester made an observation on abnormal change occurring in Chestnuts at the Bronx Zoo in New York. • The trees were developing sores that were surrounded by orange yellow and spotty patches and within a year, the disease had spread to Virginia, district of Columbia, Maryland and New Jersey (Fei et al., 2012). • The condition was determined as fungal blight caused by Cryphonectriaparasiticathe infected stem tissues and killed them through girdling them.

4. Chestnut blight Infestation Cont… • The blight was carried by wind and for every year, it spread for more than 50 miles. • Once a tree was infested, the first canker would appear causing the bark to sink or bulge. • Soon the sore would then burst causing spores to sail outward exposing the inner layers of the tree. • With time, the trees died leaving only dead stems in the woods. • The loss was stunning and between 1904 and 1940, more than 3.4 billion trees had succumbed to the fungal blight that significantly contributed to the extinction of the species.

5. The Resistance to chestnut blight • Despite the significant impact of the blight, the trees had one defense mechanism. • When the trees that was located above the ground died as a result of the infestation with the blight, the region in the soil remained (Çalişkan et aL., 2012). • As a result, the roots in various regions are constantly shooting up that has created potential for regeneration. • As a result, it has been estimated that more than 430 million trees are still growing in their native range. • Therefore, despite the significant effect on the trees by the blight, there exist potential for restoration of the trees. • As a result, efforts in rehabilitation have been considered essential in recovery of the trees. • In this regard, feedback is provided on use of genetic engineering and hybridization in restoration of the trees.

6. Restoration of the American Chestnut through Genetic Engineering • Genetic engineering has been applied as an effective tool in promoting the recovery of the American Chestnut trees. • At first, the researchers identified a gene in the wheat plant that enhanced the resistance to the fungus that caused blight. • By adding this gene to the cells of the American Chestnut, this has helped in coming up with species that are more resistance to the fungus (Jacobs et al., 2012). • Currently, test plots of genetically engineered trees have been grown in New York, Pennsylvania, and Virginia creating the potential for the restoration of the trees.

7. Restoration of the American Chestnut through Hybridization • On the other hand, the restoration through hybridization involves breeding the American trees with the Chinese species to comes up with a species that is more resistant. • Given that the blight originated from the Chinese species, the incorporation of the Chinese species into the American species has been considered effective in coming up with resistant species. • After three generations of hybridization, it has been determined that more than 96% of the trees differed from the Chinese species and were able to capture the genes for resistance to the blight (Barakat et al., 2009). • However, as compared to genetic engineering, hybridization has been considered as a less effective method in dealing with blight.

8. Conclusion • In conclusion, feedback on the extinction and the recovery of the American Chestnut trees has been provided. • For years, the American chestnut (Castanea dentata) was considered as one of the most important forest trees in the United States. • However, mature American Chestnuts have virtually become extinct that has been contributed by Chestnut blight that was a fungal diseases that causes the death of the tree. • Despite the significant impact of the blight, the trees had one defense mechanism. • When the trees that was located above the ground died as a result of the infestation with the blight, the region in the soil remained that creates potential for recovery. • Two methods that have been proven as effective for use in recovery comprise genetic engineering and hybridization that are essential in coming up with more resistant species.

9. References • Barakat, A., DiLoreto, D. S., Zhang, Y., Smith, C., Baier, K., Powell, W. A., Wheeler, N., Sederoff, R., & Carlson, J. E. (2009, May 9). Comparison of the transcriptomes of American Chestnut (Castanea dentata) and Chinese chestnut (Castanea mollissima) in response to the chestnut blight infection. BMC Plant Biology. Retrieved October 4, 2021, from https://link.springer.com/article/10.1186/1471-2229-9-51#Sec8. • ÇalişkanMahmut, Kashimshetty, Y., Simkins, M., Pelikan, S., & Rogstad, S. H. (2012). Chapter 19 Founder Placement and Gene Dispersal Affect Population Growth and Genetic Diversity in Restoration Plantings of American Chestnut. In Genetic diversity in plants (pp. 375–390). essay, InTech. • Fei, S., Liang, L., Paillet, F. L., Steiner, K. C., Fang, J., Shen, Z., Wang, Z., & Hebard, F. V. (2012, February 11). Modelling chestnut biogeography for American Chestnut Restoration. Wiley Online Library. Retrieved October 4, 2021, from https://onlinelibrary.wiley.com/doi/full/10.1111/j.1472-4642.2012.00886.x. • Jacobs, D. F., Dalgleish, H. J., & Nelson, C. D. (2012, November 19). A conceptual framework for restoration of THREATENED plants: The effective model of American chestnut (Castanea dentata) reintroduction. New Phytologist Foundation. Retrieved September 28, 2021, from https://nph.onlinelibrary.wiley.com/doi/full/10.1111/nph.12020. • Powell, W. A., Newhouse, A. E., & Coffey, V. (2015). Developing Blight-Tolerant American chestnut trees. Cold Spring Harbor Perspectives in Biology. Retrieved September 28, 2021, from https://cshperspec tives.cshlp.org/content/11/7/a034587.full.pdf.