A hundred and fifty years ago, American Chestnut trees provided food for people and animals throughout the eastern United States, as well as lumber. Then, a fungus from Asia nearly wiped them out.
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Researchers have been working to bring them back, but, a genetically modified chestnut program hit a snag last year, leaving many chestnut fans wondering, what’s next?
A few miles from Abingdon in Southwest Virginia, tens of thousands of chestnut trees are growing in an orchard surrounded by hilly cow pastures. Most of these trees are young. But they’re descended from chestnut seedlings that researchers bred a hundred years ago.
“With each successive generation you’re trying to retain as much as much resistance as possible,” said Vasiliy Lakoba, director of research at the American Chestnut Foundation’s first, and largest, research orchards in Meadowview.
A groundhog scurries in the grass as he points to one tree, a hybrid Chinese and American chestnut.
“Well when we say hybrids, we mean that the genetics of the two species becomes mixed,” Lakoba said.
This isn’t genetic modification done in a lab, this is someone nudging the tree along. “When you as a person take pollen from one tree that you’ve collected, and you put it on the female flowers of another tree,” explained Lakoba.
Scientists have been trying to help restore chestnuts this way since the early 1900s.
A GMO variety
Researchers in New York, meanwhile, have been working on something entirely different, a genetically modified American chestnut, called Darling 58. They found a way to insert a gene from wheat into an American chestnut—supposedly making it resistant to the blight.
But recently, the American Chestnut Foundation announced they’re no longer supporting the Darling GMO project.
“We have evidence that the trees are not performing well in the field,” said Sara Fern Fitzsimmons, chief conservation officer with the American Chestnut Foundation.
She said the Darling trees are growing slowly, and don’t appear to resist the blight after a year. They also discovered a genetic deficiency, when they learned there had been a labeling issue— the trees are in fact a different version of the Darling line, called Darling 54. These trees are problematic for restoration, Fitzsimmons said.
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“The Darling 54 trees have an interrupted native gene coding for salinity and drought tolerance, one which chestnuts need to be healthy,” Fitzsimmons said. The inserted wheat gene, she said, interrupts them. This, along with other factors, could explain why the Darling trees have stunted growth.
Andy Newhouse disagrees. “The Darling Chestnuts are still the most promising option we have.” Newhouse is the director of the chestnut project at the State University of New York College of Environmental Science and Forestry, where researchers developed the Darling line of chestnuts.
“We’re moving forward,” Newhouse said. “We’re studying the trees. We’re working to improve them.”
Newhouse’s team has applied to the United States Department of Agriculture for permission to release their GMO trees. The USDA could make a decision this year.
Amy Brunner, associate professor at Virginia Tech, holds a small chestnut seeding growing in a plastic box. Her lab is researching the genes that provide blight resistance in chestnut trees. Credit: Roxy Todd / Radio IQ
Finding the right piece of the puzzle
Meanwhile, other genetic researchers here in Virginia are working to better understand the specific genes that help some chestnut trees resist blight.
Inside a lab on Virginia Tech’s campus, researcher Amy Brunner points to dozens of seedlings sprouting in tiny plastic boxes. Grow lights give the room an almost X-files vibe.
These seedlings were recently sprouted from nuts collected on orchards in Kentucky, Pennsylvania and Virginia. Brunner said the future of this science could include both genetic modification, as well as traditional hybrid breeding.
“Compared to crops, the amount of researchers that are focused on forest trees, using the type of research we do, the molecular genetics and genomics, is relatively small,” Brunner said.
Her colleague John McDowell is also hoping to study the genetic sequence of the fungus that causes blight, which could help restore American chestnuts back to the forests.
“They used to be keystone species in the eastern forests. They were great sources of timber and food,” McDowell said. “They underpinned a lot of local economies.”
Back on the Meadowview orchard, Lakoba points to another young hybrid chestnut tree that shows promise. It’s tall and straight, and its nuts look similar to American chestnuts. And, after fifteen years, it appears to be fighting off blight.
Genetic research can speed up the process, but Lakoba said it may take 100 more years for scientists to get an ideal tree that will survive in the wild.
He said one single solution won’t solve it. It will take different breeding methods, and scientists across the country, to return chestnuts back to the forests.
This report, provided by Virginia Public Radio, was made possible with support from the Virginia Education Association. Radio IQ is a service of Virginia Tech.
