Dutch Elm Disease Population Genomics

Research Issue

[photo] American elm tree in plantation showing symptoms of Dutch elm disease.Dutch Elm Disease (DED), caused by the fungi Ophiostoma ulmi and Ophiostoma novo-ulmi, continues to weaken and kill American elm trees in forests and cities. “Survivor elms” (mature trees that are still alive in forests and seem to have some natural tolerance to DED) have been used for DED tolerance breeding programs aimed at restoring American elm trees.

Breeding programs test DED tolerance of American elm cultivars with laboratory strains of the DED fungi. However, these laboratory strains were collected decades ago and may not be representative of current strains found in the environment. Fungal pathogens evolve alongside their hosts. Therefore, it is likely that the Ophiostoma strains causing DED today are genetically different from those that caused disease decades ago.

To determine the genetic variability of Ophiostoma strains currently in the environment, we are collecting and studying fungal strains from naturally infected American elm trees. We will sequence the genomes of some of these strains in order to understand the current population genetics of the fungi causing DED in American elms.

Our Research

Fungi have relatively small genomes (~30 Mb). With recent advances in next-generation sequencing (NGS) technologies, we can quickly get whole genome sequencing data for fungi in a cost-effective way. Using several computational approaches, we can analyze the whole genome data to identify fine-scale genetic differences within strains of the same species.

Just as there are strains of the flu virus that cause people to get especially sick, there are strong (also called virulent) strains of the DED-causing fungi that kill trees more quickly than others. Ophiostoma strains isolated in the lab will be used in field-based studies on American elm trees to see which strains are the most virulent. 

Expected Outcomes

By linking the genome sequencing data to field-based studies, we will be able to identify virulence factors in Ophiostoma and ensure that existing breeding programs are selecting for DED tolerance that will continue into the future.

Research Participants

Principal Investigators

  • Jonathan Palmer, Formerly with U.S. Forest Service Northern Research Station, Research Biologist
  • Jessie Glaeser, U.S. Forest Service Northern Research Station, Research Plant Pathologist
  • Charles Flower, U.S. Forest Service Northern Research Station, Research Ecologist,
  • Kathleen Knight, U.S. Forest Service Northern Research Station, Research Ecologist
  • Cornelia Pinchot, U.S. Forest Service Northern Research Station, Research Ecologist
  • James Slavicek, U.S. Forest Service Northern Research Station, Research Biologist (retired)

 

 

  • Last modified: May 6, 2019