Chestnut project | Poplar project | Elm project| Publications | Patent

Chestnut Project,

Restoration of an American heritage tree

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



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American Elm 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.

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Poplar Project

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.



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Sisco, P.H., Sederoff, R.R., Tomkins, J.P., Carlson, J.E., Kubisiak, T.L., Staton, M.E., Hebard, F.V., Anagnostakis, S.L., Powell, W.A. and Smith, C.P. 2009. The United States National Science Foundation project on developing tools for the study of the Fagaceae: Castanea, Quercus, and Fagus. Acta Hort. (ISHS) 844:267-274

Barakat, A., D. S. DiLoreto, Y. Zhang, C. Smith, K. Baier, W. A. Powell, N. Wheeler, R. Sederoff, J. E. Carlson. 2009. Comparison of the transcriptomes of American chestnut (Castanea dentata) and Chinese chestnut (Castanea mollissima) in response to the chestnut blight infection. BMC Plant Biology. 9:51 (pp. 1-11)

Andrew E. Newhouse, Nicholas S. Kaczmar, Charles A. Maynard. American Elm, in Kole, C. and Hall, T. C. (eds.), “Compendium of Transgenic Crop Plants: Transgenic Forest Tree Species”, Blackwell Publishing, Oxford, UK, 2008, pp 241-262

Maynard, C.A., W.A. Powell, L.D. Polin-McGuigan, A.M. Viéitez, A. Ballester, E. Corredoira, S.A. Merkle and G.M. Andrade (2008) Chestnut. In: Kole, C., Hall, T.C. (eds.) “A Compendium of Transgenic Crop Plants: Forest Tree Species”, Blackwell Publishing, Oxford, UK, 2008.

Newhouse, A.E., F. Schrodt, H. Liang, C.A. Maynard, W.A. Powell. 2007. Transgenic American Elm Shows Reduced Dutch Elm Disease Symptoms and Normal Mycorrhizal Colonization. Plant Cell Reports 26:977-987

Welch, A.J., C.A. Maynard, A.J. Stipanovic, and W.A. Powell. 2007. The effects of oxalic acid on transgenic Castanea dentata callus tissue expressing oxalate oxidase. Plant Science 172:488-496


Powell, W. A., P. Morley, M. King and C. A. Maynard. 2007. Small stem chestnut blight resistance assay. Journal of The American Chestnut Foundation 21(2): 34-38

Rothrock, R., L. McGuigan, A. Newhouse, W.A. Powell and C.A. Maynard. 2007. Plate Flooding as an Alternative Agrobacterium-Mediated Transformation Method for American Chestnut Somatic Embryos. Plant Cell Tissue and Organ Culture 88:93-99

Merkle, S.A., G.M. Andrade, C.J. Nairn, W.A. Powell and C.A. Maynard. 2007. Restoration of threatened species: a noble cause for transgenic trees. Tree Genetics and Genomes 3:111-11

Polin L.D., H. Liang, R. Rothrock, M. Nishii, D. Diehl, A. Newhouse, C.J. Nairn, W. A. Powell, and C.A. Maynard. 2006. Agrobacterium-mediated transformation of American chestnut (Castanea dentata (Marsh.) Borkh.) somatic embryos. Plant Cell Tissue and Organ Culture. 84: 69-79

Powell, W.A., C.A. Maynard, B. Boyle, and A. Seguin. (2006). Fungal and bacterial resistance in transgenic trees. Pages 235-252. In: M. Fladung and D. Ewald, Eds., Tree Transgenics, Recent Developments. Springer, Berlin Heidelberg, Germany. 357p.

Newhouse, A., F. Schrodt, C. Maynard, and W. Powell. (2006). American elm (Ulmus americana). Pages 99-112 In: K. Wang, Ed., Agrobacterium Protocols: (2nd edition) Methods in Molecular Biology Book Series #344, Humana Press, Inc., Totowa, NJ. 485 pages

Maynard, C.A., L. D. Polin, S. LaPierre, R. E. Rothrock, and W. A. Powell. (2006). American chestnut (Castanea dentata (Marsh.) Borkh.). pages 239-251. In: K. Wang, Ed., Agrobacterium Protocols: (2nd edition) Methods in Molecular Biology Book Series #344, Humana Press, Inc., Totowa, NJ.

Liang, H., H. Gao, C.A. Maynard, and W.A. Powell. 2005. Expression of a self-processing, putative pathogen resistance-enhancing gene construct in Arabidopsis. Biotech. L. 27:435-442

Connors, B.J., M. Miller, C.A. Maynard, and W.A. Powell. 2002. Cloning and characterization of promoters from American chestnut capable of directing reporter gene expression in transgenic Arabidopsis plants. Plant Science 163:771-781
Connors, B.J., N.P. Laun, C.A. Maynard, and W.A. Powell. 2002. Molecular characterization of a gene encoding a cystatin expressed in the stems of American chestnut (Castanea dentata). Planta 215:510-514
Liang, H. C.M. Catranis, C.A. Maynard, and W.A. Powell. 2002. Enhanced resistance to the poplar pathogen, Septoria musiva, in hybrid poplar transformed with genes encoding antimicrobial peptides. Biotechnol. Lett. 24(5):383-389
Connors, B.J., C.A. Maynard, and W.A. Powell. 2001. Expression sequence tags from stem tissue of American chestnut. Biotechnol. Lett. 23:1407-1411
Liang, H., C.A. Maynard, R.D. Allen, W.A. Powell. 2001. Increased Septoria musiva resistance in transgenic hybrid poplar leaves expressing a wheat oxalate oxidase gene. Plant Mol. Biol. 45:619-629
Powell, W.A., C.M. Catranis, and C.A. Maynard. 2000. Design of self-processing antimicrobial peptides plant protection. Letters in Applied Microbiology 31:163-168
Xing, Z.Z., W.A. Powell, and C.A. Maynard. 1999. Development and germination of somatic embryos in American chestnut. Plant Cell Tissue and Organ Culture 57:47-55
Maynard, C., Z. Xing, S. Bickel, and W. Powell. 1999. Using Genetic Engineering to Help Save the American Chestnut: A Progress Report. Journal of the American Chestnut Foundation, 12 (2):41-56.
Powell, W.A. and C.A. Maynard. 1997. Designing small antimicrobial peptides and their encoding genes. pp.165-172. In Micropropagation, Genetic Engineering, and Molecular Biology of Populus , N.B. Klopfenstein, Y.W. Chun, M.-S. Kim, M.R. Ahuja, eds. M.C. Dillon, R.C. Carman, L.G. Eskew, tech. eds. Tech. Rep. RM-GTR-297. Fort Collins, CO: U.S. Department of Agriculture, Forest Service, Rocky Mountain Forest and Range Experiment Station. 310p.
Xing, Z., M.F. Satchwell, W.A. Powell, and C.A. Maynard. 1997. Micropropagation of American chestnut: Increasing rooting rate and preventing shoot-tip necrosis. In Vitro Cellular and Developmental Biology-Plant 33:43-48
Kistler, H.C., U. Benny, and W.A. Powell. 1997. Linear mitochondrial plasmids of Fusarium oxysporum contain genes with sequence similarity to a reverse transcriptase from Neurospora spp. Applied and Environmental Microbiology 63:3311-3313
Powell, W.A., C.M. Catranis, and C.A. Maynard. 1995. Synthetic Antimicrobial Peptide Design. Molecular Plant-Microbe Interactions 8:792-794
Powell, W.A. 1995. Vegetative incompatibility and mycelial death of Cryphonectria parasitica monitored with pH indicators. Mycologia 87:738-741
Powell, W.A. and Z.H. Yan. 1995. Recombination between Fusarium oxysporum telomeres and pUC ampicillin resistance gene in a transforming vector. Fungal Genetics Newsletter 42:62-64
Rizwana, R. and W.A. Powell. 1995. Ultraviolet light-induced heterokaryon formation and parasexuality in Cryphonectria parasitica. Experimental Mycology 19:48-60
Rizwana, R. and W.A. Powell. 1992. Ultraviolet light-induced instability of vegetative compatibility groups of Cryphonectria parasitica. Phytopathology 82:1206-1211
Milgroom, M.G., S.E. Lipari, and W.A. Powell. 1992. DNA fingerprinting and analysis of population structure in the chestnut blight fungus, Cryphonectria parasitica. Genetics 131:297-306
Powell, W.A. and H.C. Kistler. 1990. In vivo rearrangement of foreign DNA by Fusarium oxysporum produces linear self-replicating plasmids. J. Bact. 172:3163-3171
Gobbi, E., Y. Wang, R.M. Martin, W.A. Powell, and N.K. Van Alfen. 1990. Mitochondrial DNA of Cryphonectria parasitica: lack of migration between vegetatively compatible strains. Molecular Plant-Microbe Interactions 3:66-71
Powell, W.A. and N.K. Van Alfen. 1987. Differential accumulation of poly(A)+ RNA between virulent and dsRNA-induced hypovirulent strains of Cryphonectria (Endothia) parasitica. Mol. Cell. Biol. 7:3688-3693
Powell, W.A. and N.K. Van Alfen. 1987. Two non-homologous viruses of Cryphonectria (Endothia)parasitica reduced the accumulation of specific virulence associated polypeptides. J. Bact. 169:5324-5326
Hansen, D.R., N.K. Van Alfen, K. Gillis, and W.A. Powell. 1985. Naked dsRNA associated withhypovirulence of Endothia parasitica is packaged in fungal vesicles. J. Gen. Virol. 66:2605-2614


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U.S. Patent

Title: Antimicrobial Peptides

Covers genes encoding antimicrobial peptides designed for enhancing pathogen resistance in plants.

U.S. Patent No. 5,856,127

Date of Patent: 1/5/99

Abstract: The present invention is directed to antimicrobial polypeptides and to nucleic acid molecules encoding the antimicrobial polypeptides. The polypeptide consists of 15 to 20 amino acids and has an amphipathic alpha helix structure, wherein 3 or more of the amino acids form a positively charged domain extending axially along the alpha helix. Expression vectors, host cells, and transgenic plants, as well as methods of producing plants having improved resistance to fungal and bacterial infestation, are also proved.

For full text click here