Dutch Elm Disease (DED), caused by the fungi Ophiostoma ulmi and Ophiostoma novo-ulmi, continues to weaken and kill American elm trees (Ulmus americana) 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, U.S. Forest Service researchers are collecting and studying fungal strains from naturally infected American elm trees. U.S. Forest Service Northern Research Station Principal Investigators Jonathan Palmer, Jessie Glaeser, Charles Flower, Kathleen Knight, Cornelia Pinchot, and James Slavicek 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. Read more here. Photo Courtesy USFS