Cloning of American Elm (Ulmus americana L.)

Cloning of American Elm (Ulmus americana L.)

Majestic American elms were among the most popular and recognizable trees in North America, lining boulevards and adorning city centres.  Unfortunately, Dutch elm disease (DED) has now wiped out more than 95 per cent of the American elm population in Eastern Canada and the United States. DED is caused by a fungal infection, which interferes with the circulation of water and nutrients, resulting wilting symptoms and eventual death. Only about one in 100,000 elms may be naturally tolerant to the pathogen. These survivors are invaluable as they have survived repeated outbreaks of DED and represent potential sources of tolerant trees for distribution and future breeding efforts. An efficient procedure for in vitro propagation and conservation of mature American elm trees has been developed at GRIPP.

The procedure involves in vitro proliferation of fresh and dormant buds from mature trees for cloning ‘survivor’ American elm trees. The key factors that influenced sustained growth and multiplication included optimization of culture process in relation to auxin metabolism in the source tissue. This technology is expected to facilitate the conservation of elite germplasm, screen large populations of in vitro generated plants for disease resistance, reintroduction of resistant genotypes in the landscape, and as a resource for future breeding efforts. The systematic optimization of culture parameters can serve as a model to improve conservation of tree species.

Selected Publications

  • Shukla, M.R., Jones, A.M.P., Sullivan, J.A., Liu, C., Gosling, S., Saxena, P.K. (2012). In vitro conservation of American elm (Ulmus americana): potential role of auxin metabolism in sustained plant proliferation. Canadian Journal of Forest Research 42(4): 686-697, doi: 10.1139/ X2012-022. [http://www.nrcresearchpress.com/doi/abs/10.1139/X2012-022]