Dr. William A. Powell, Research and Publications

The American chestnut tree, Castanea dentata, was once one of the most important and abundant trees in the eastern United States. Just before 1900, a pathogen, Cryphonectria parasitica, (formally Endothia parasitica) was introduced into the U.S. and within about 50 years reduced the American chestnut from its predominant role in the forest as a keystone species, to now an understory shrub struggling to survive. The reason American chestnuts still survive today is due to there ability to resprout from their root collar. Unfortunately, the chestnut blight usually kills the tree back to the ground before it matures. The American chestnut research and restoration project is a collaborative effort to produce blight-resistant American chestnut through the use of genetic engineering. Our lab is focused on the identification and cloning of genes and promoters that can be used to enhance blight resistance in American chestnut trees. Our first transgenic somatic embryo cultures were produced in the spring of 2004 (the one hundred year anniversery of the discovery of the chestnut blight in 1904). Shoots have been regenerated from these cultures in the fall of 2004. Whole potted plants are expected in 2005 and field trials are scheduled to begin the following spring in 2006.

also see: NYS American Chestnut Research and Restoration Project

The American elm tree is another heritage tree that once graced the streets of many U.S. towns. For example, in 1950 Syracuse, New York had about 53,000 elms along its streets, but today it is difficult to find any survivors due to the introduced Dutch elm disease. In an effort to restore this tree, we have developed tissue culture and transformation techniques. Field trials of the first transgenic American elms expressing ESF antimicrobial peptides in their vascular tissues have begun in 2005.

Hybrid poplar is an important woody biomass and potential bioenergy tree species. Utilization of these trees are limited in the eastern United States due to a fungal pathogen, Septoria musiva. We have made several gene constructs encoding gene products to enhance poplar¼s resistance to Septoria canker and leaf spot and also other fungal pathogens. Some of the genes we are currently testing singularly and in combinations are: synthetic antimicrobial peptides (ESF peptides), oxalate oxidase from wheat, and a chitinase from Trichoderma, and cystatin (a proteinase inhibitor) from American chestnut. We are also testing the use of TMV¼s NIa protease to deliver multiple gene products from a single gene construct. We have produced several transgenic hybrid poplar which we have tested in vitro and are currently testing in the field.