Student Spotlight on Avalon Miller: Using emerging technologies to save American elm trees

American elm trees play a crucial role in forest ecosystems, supporting a diversity of insects, birds and mammals. These beautiful, vase-shaped trees were also a favorite in urban landscaping, including in the iconic Old Main lawn at Penn State University. Unfortunately, for decades, these trees have been threatened by an aggressive pathogen. In collaboration with US Forest Service ecologists, Penn State graduate student Avalon Miller is integrating traditional methods with emerging technologies to help save the American elm, and potentially other trees that are threatened by pests and diseases.

“It's an exciting time in plant research as we are beginning to apply decades of insights from model plant species like tomato and wheat to more complex tree systems”, Avalon says. Her research integrates metabolomics, spectroscopy and artificial intelligence to rapidly screen for trees that are resistant to Dutch Elm Disease.

Dutch Elm Disease (DED) is a devastating disease that has killed millions of American elm trees. DED is caused by an invasive fungal pathogen called Ophiostoma novo-ulmi, which was introduced to North America in the 1930s. In the decades following the loss of American elms, other tree species, such as green ash, now face new threats like the Emerald Ash Borer. However, since the 1930s, several resistant American elm genotypes have been identified. Therefore, a promising restoration strategy involves using these resistant American elms to help mitigate the impacts of current and future threats facing other tree species.

The best strategy to save and restore American elm populations is to develop genetically diverse, DED-resistant populations by identifying and cultivating resistant survivor trees. However, current methods for screening trees for DED resistance are expensive and time-intensive, and there is limited knowledge about the traits responsible for resistance in American elms. Therefore, scientists are working to develop high-throughput screening techniques to identify resistant cultivars for breeding programs.

Avalon is testing whether changes in metabolites in the leaves of trees exposed to O. novo-ulmi can be used to differentiate between DED-resistant and susceptible genotypes. She is using Near-Infrared Spectroscopy (NIRS) to identify these metabolites based on their unique chemical signatures and is developing machine learning models that integrate NIRS and metabolomics data to predict disease resistance. This metabolite profiles may also help scientists find new genetic and molecular pathways for disease resistance.

If these studies are successful, it may be possible to scale up screening for resistant trees from greenhouses and nurseries to forests. In the future, Avalon and her collaborators hope to integrate NIRS sensors on to unmanned aerial vehicles (UAVs) to assess tree and forest health .

This innovative integration would facilitate rapid screening for disease resistance in forests, marking a significant advancement in plant health management.

Avalon is hopeful that her research will not only help American elm trees, but also other trees that are threatened by pests and diseases. Avalon says, “Research groups worldwide are making significant advancements, particularly in the presymptomatic detection of diseases affecting tree species like oak, ash, and pine. I hope that our work will play a little part in helping the community move towards applying these technologies to identify disease-resistant trees and helping to combat the many diseases threatening our forests.”

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Avalon Miller is a Ph.D. candidate in the Department of Plant Pathology and Environmental Microbiology at Penn State University, advised by Dr. Cristina Rosa. Her work, funded by the U.S. Forest Service, the Manton Foundation, and the USDA McIntire-Stennis Cooperative Forestry Program.

This article was written by Varun Parekh, a PhD student mentored by Vijaykrishnan Narayanan in the Department of Computer Science and Electrical Engineering. It was prepared as part of the INSECT NET Science Communication workshop series coordinated by Drs. Christina Grozinger and Natalie Boyle during summer 2024.