Genetic Studies of American Elm

In summer 2017, we collected and freeze-dried leaves from about 800 DED-tolerant trees that had been planted in forests. In a few years, when we know which trees are cold tolerant and which are not (the dead ones), we will extract and study DNA from the freeze-dried leaves. This will allow us to study the DNA of trees even after they have died.

Research Issue

American elm seedlings that will be tested for tolerance to Dutch elm disease.

Until the 1920s, American elm trees (Ulmus americana) were widely distributed in eastern U.S. forests. The arrival of Dutch Elm Disease (DED, caused by the fungi Ophiostoma ulmi and O. novo-ulmi) changed that. Today very few mature elms survive in American forests and cities.

Our Research

For over 20 years, Northern Research Station scientists have been working to breed genetically diverse American elm trees that are tolerant to DED. Here are three examples of our genetics research:

  1. Developing a genetic map of American elm. We will use the genetic map to locate genes linked to DED resistance. With this information, we will be able to increase the speed and efficiency of the breeding program that develops DED-resistant elms.
  2. Identifying genes that contribute to cold tolerance in American elm. To restore American elms to many natural habitats and cities, we need to make sure they can survive harsh winters in addition to being resistant to DED. As in all breeding programs, our goal is to identify which trees have characteristics we want (such as cold tolerance) and isolate their DNA..
  3. Sequencing the entire genome of American elm. Twenty years ago, sequencing every base of DNA in a plant cost millions of dollars and took years. Now, it can be done for about 1% of those costs in 6-12 months, depending on staff. A full DNA sequence (“genome”) for American elm is important because it can be used to understand what genes are present and how they are organized. Much of the data for assembling the genome of American elm has already been gathered. Eventually, we will be able to understand how American elms from one part of the country are different from those in other parts of the country.

Expected Outcomes

Once we have mapped American elm DNA, we will be able to study genetic differences between individual trees that share traits like cold tolerance or that come from different parts of the U.S. We hope to identify and breed American elms that are DED resistant and cold tolerant enough for planting in the northern U.S. These are important steps toward restoring American elms to forests and cities.

Our Research

For over 20 years, Northern Research Station scientists have been working to breed genetically diverse American elm trees that are tolerant to DED. Here are three examples of our genetics research:

  1. Developing a genetic map of American elm. We will use the genetic map to locate genes linked to DED tolerance. With this information, we will be able to increase the speed and efficiency of the breeding program that develops DED-tolerant elms.
  2. Identifying genes that contribute to cold tolerance in American elm. To restore American elms to many natural habitats and cities, we need to make sure they can survive harsh winters in addition to being tolerant to DED. As in all breeding programs, our goal is to identify which trees have characteristics we want (such as cold tolerance) and isolate their DNA.
  3. Sequencing the entire genome of American elm. Twenty years ago, sequencing every base of DNA in a plant cost millions of dollars and took years. Now, it can be done for about 1% of those costs in 6-12 months, depending on staff. A full DNA sequence (“genome”) for American elm is important because it can be used to understand what genes are present and how they are organized. Much of the data for assembling the genome of American elm has already been gathered. Eventually, we will be able to understand how American elms from one part of the country are different from those in other parts of the country.

Expected Outcomes

Once we have mapped American elm DNA, we will be able to study genetic differences between individual trees that share traits like cold tolerance or that come from different parts of the U.S. We hope to identify and breed American elms that are DED tolerant and cold tolerant enough for planting in the northern U.S. These are important steps toward restoring American elms to forests and cities.

Research Results

Pinchot, C.C.; Flower, C.E.; Knight, K.S.; Marks, C.; Minocha, R.; Lesser, D.; Woeste, K.; Schaberg, P.G.; Baldwin, B.; Delatte, D.M.; Fox, T.D.; Hayes-Plazolles, N.; Held, B.; Lehtoma, K.; Long, S.; Mattix, S.; Sipes, A.; Slavicek, J.M. 2017. Development of new Dutch Elm disease-tolerant selections for restoration of the American Elm in urban and forested landscapes. In: Sniezko, Richard A.; Man, Gary; Hipkins, Valerie; Woeste, Keith; Gwaze, David; Kliejunas, John T.; McTeague, Brianna A., tech. cords. 2017. Gene conservation of tree species—banking on the future. Proceedings of a workshop. Gen. Tech. Rep. PNW-GTR-963. Portland, OR: U.S. Department of Agriculture, Forest Service, Pacific Northwest Research Station: 53-63.

Slavicek, James M.; Baggett, Kelly; Swanson, Gary. 2009. Restoration of the American elm on the Chippewa National Forest through generation of Dutch elm disease tolerant, cold-hardy, and site-adapted trees. In: McManus, Katherine A; Gottschalk, Kurt W., eds. Proceedings. 20th U.S. Department of Agriculture interagency research forum on invasive species 2009; 2009 January 13-16; Annapolis, MD. Gen. Tech. Rep. NRS-P-51. Newtown Square, PA: U.S. Department of Agriculture, Forest Service, Northern Research Station: 95.

Research Participants

Principal Investigator

  • Keith Woeste, US Forest Service Northern Research Station, Research Geneticist

Research Partners

 

  • Last modified: May 6, 2019