About This Project

The American chestnut, Castanea dentata, was devastated by an exotic fungal pathogen, Cryphonectria parasitica. Endophytes, organisms that reside within host plant tissue without causing symptoms, may be a reservoir for sources of biocontrol agents active against C. parasitica. Endophytes isolated from chestnut stems have shown antagonism against the blight fungus in in vitro dual-culture experiments and now need tested in living seedlings.

Ask the Scientists

What is the context of this research?

In the early 1900's a fungal blight, Cryphonectria parasitica, was introduced to the forests of eastern North America. This fungus proved a devastating pathogen to the American chestnut, Castenea dentata. Chestnut was once the dominant tree of Appalachian forests, forming an emergent canopy that towered above the rest of the forest. These trees were once a keystone species which raised the carrying capacity for species that utilized the nuts as food (as well as predators of those species). The nut crop and wood of these trees were also important human resources.

American chestnut still survives in the forest as a shrub; its roots are not killed by the blight. It continually re-sprouts from these rootstocks, however the stems are attacked and killed before they are mature.

What is the significance of this project?

Efforts to revive the American chestnut began with conventional breeding programs intended to increase tree resistance to the blight fungus. The most well known of which is the American Chestnut Foundations backcross breeding program; this effort has attempted to breed genes from resistant Chinese chestnuts into American lineages. Most recently genetically modified trees, which contain a gene from wheat, have also been produced and are completely resistant.

Fungal endophytes isolated from healthy American chestnuts may provide a new source of blight resistance. Resistance conferred by an endophyte may be applicable in genetically pure American trees, as well as complementary to the aforementioned breeding efforts. Restoring the chestnut will be a boon for wildlife and humans alike.

What are the goals of the project?

Having already identified an endophyte highly antagonistic to blight following in vitro (dual-culture on potato dextrose agar) testing, its activity must be confirmed in vivo (in live chestnut seedlings). If shown to be successful, field trials could begin with out-planted, inoculated seedlings. Development of an endophyte for use as biocontrol against the blight will ultimately help restore the American chestnut to our forests. This will increase the carrying capacity for our native wildlife and restore an important food and timber resource to our communities.