Collaborative research conducted by scientists from U.S. Department of Energy’s Oak Ridge National Laboratory (ORNL) and scientists from the State University of New York College of Environmental Science and Forestry (ESF), funded by the American Chestnut Foundation has found that the addition of a gene from a wheat variety to the American Chestnut’s genome produces increased resistance to the chestnut blight. Using gas chromatography mass spectrometry the team, led by Drs. William Powell and Charlie Maynard of ESF, were able to analyze transgenic chestnut trees in which they had inserted a wheat gene. The results indicated metabolite concentration levels similar to non-transgenic samples, meaning they are edible. Dr. Timothy Tschaplinski of ORNL’s Energy and Environmental Sciences Directorate elaborates:
“We found that the wheat gene kept oxalic acid (oxalate) concentration-a key fungal necrotic agent-from accumulating, and the only substantial difference from non-resistant trees was a slightly lower level of gamma-tocopherol, a form of vitamin E.” Gamma tocopherol levels were consistent with non-transgenic Chinese chestnuts, eaten the world over.
Chestnut blight is caused by the fungus, Cryphonectria parasitica, a disease accidentally introduced from Asia in the 1800s. Since the time of its introduction this fungus has wreaked havoc on American chestnut populations. The American chestnut tree naturally has very little resistance to the disease, basically any adult tree will succumb to the disease very quickly; in as little as 3 days fungi have been identified girdling the stems of test seedlings. The fungus’s production of oxalate contributes to its virulence; oxalate causes rapid rotting of chestnut tissues. The gene procured from wheat, oxalate oxidase, and inserted into the chestnut’s DNA by the scientists from ESF, breaks down oxalate limiting C. parasitica‘s deadly effects. Slowing the accumulation of oxalate by the fungus impedes disease progression.
In addition to their previous, iconic dominance of the forest landscape, the American chestnut used to be a significant source of mast and habitat for wildlife. Their loss has been felt throughout the ecosystem, as well as in suburbia where they were often planted as street trees. Prior to widespread planting of transgenic chestnut trees, they will be subjected to further research and scrutiny before receiving regulatory approval by U.S. Food and Drug Administration and U.S. Department of Agriculture Animal and Plant Health Inspection Service.
