Chestnut Blight Research
Laurel Speilman '03
Summer 2001

     Laurel Speilman, supported by an Honors Summer Research Program fellowship, is studying two aspects of the interaction between the American chestnut (Castanea dentata) and its lethal fungal blight (Cryphonectria parasitica). Advised by Professor Linda Fink, Laurel is working also with Professor Gary Griffin (Virginia Tech) and with Dr. John Scrivani (Virginia Department of Forestry).

The Hunt for Blight Resistance
The VA Department of Forestry maintains a hybrid chestnut plantation at the Lesesne State Forest in Nelson County, Virginia. Scientists have hybridized American chestnuts with blight-resistant Chinese chestnuts, and are backcrossing the hybrids to pure American trees. Offspring with phenotypic characteristics of American chestnuts plus blight resistance are selected for further breeding. After several generations of backcrosses, scientists will be producing blight-resistant trees with predominantly American chestnut characteristics.
Leaves of the American chestnut		Leaves of an American-Chinese hybrid showing Chinese characteristics
VA Dept. of Forestry truck used for bagging inflorescences for hand pollination		Chestnut killed this season by blight
Laurel's work at the Lesesne has been to evaluate the first backcross generation (3/4 American:1/4 Chinese) for blight resistance by rating the cankers produced by trees that are under attack. She will identify genetic lines with high and low resistance by comparing the survival rates of the trees derived from different chestnut parents.
Chestnut Blight and Tannins
The chestnut blight fungus is unusual in using tannins as a source of nutrients, and the American chestnut has very high tannin concentrations. Most fungi are inhibited by tannins, and the antifungal role of these compounds in many plants has been well studied. The ability of the chestnut blight to survive and, in fact, thrive in the presence of tannins is part of its success story.      Laurel is conducting a laboratory study comparing the effect of tannin concentration on the growth of chestnut blight from several sources, of another fungus found on chestnut, and of fungi cultured from dogwood and sassafras trees.
Growth of chestnut blight fungus on potato dextrose agar with no tannins. 7 days.		Growth of chestnut blight fungus on potato dextrose agar with 4mg/ml tannins. 7 days.

Further information on efforts to reestablish the American chestnut:
American Chestnut Cooperators' Foundation
American Chestnut Foundation
Other chestnut links

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URL: //nature.sbc.edu/studentwork/speilman/chestnut.html       email: naturalist@sbc.edu

This site is maintained by Professor Linda S. Fink  (434) 381-6436
Department of Biology
Sweet Briar College, Sweet Briar VA 24595
Last updated:1 July 2001
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