Protoplast Technologies in American Elm

Development of Protoplast Technologies for American Elm

Plant protoplasts, also known as “naked cells”, are the living components of the plant cell after the cell wall has been removed.  Once the cell wall is removed, the protoplasts can be used for a variety of fundamental scientific studies as well as more practical applications such as protoplast fusion.  In the process of protoplast fusion, two separate cells are combined into a single cell that contains both partners’ genetic material.  This approach has been used in various species to overcome sexual barriers and create inter-specific hybrids that display unique characteristics such as disease resistance.  In regard to elm, this approach could facilitate the integration of DED resistance from sexually incompatible Asiatic elms into the American elm germplasm.

This approach has been proposed for the development of DED resistant elm hybrids as early as the 1980s, but has remained elusive in large part due to the difficulties isolating and manipulating American elm protoplasts.

Recent work at GRIPP has developed a novel method to facilitate efficient protoplast isolation by selective inhibition of the phenylpropanoid pathway. The significance of this study lies in its innovative and systematic approach to develop an effective solution to a problem that has limited the progress in protoplast based genetic improvement of American elm. Protoplasts isolated using this system displayed high rates of viability, initiated cell division sooner and at a high frequency, and have facilitated the recovery of protoplast-derived callus and shoot buds in this species for the first time.

This technology also provides a novel approach to expand the application of protoplast technologies to traditionally recalcitrant woody species in which cell wall digestion and reproducible protoplast isolation has proven to be very difficult, if not impossible. Ongoing studies indicate that this approach enables protoplast isolation in other woody species including sugar maple (Acer saccharum) and hazelnut (Corylus sp.).

Selected Publications

  • Jones, AMP, et al. (2012). "Inhibition of phenylpropanoid biosynthesis increases cell wall digestibility, protoplast isolation, and facilitates sustained cell division in American elm (Ulmus americana)." BMC Plant Biology 12 (1): 75. []