Looking at the modified trees, Westbrook noticed something was wrong. He noticed a tall tree next to a tree that was lower than normal. One is tall and the other is short. This means some individuals may not be able to compete with sunlight if released into the wild.
The team was scheduled to work with a tree named Darling 58, developed by the State University of New York School of Environmental Science and Forestry (SUNY ESF). However, Westbrook and others soon realized that many of the trees they were working with were not Darling 58 trees at all. They were chestnuts of different varieties, and the gene had been inserted in the wrong place.
The mistake turned out to be the latest in a series of concerns that led the American Chestnut Foundation to discontinue support for the Darling Line this month. The development has caused a rift in the passionate community and left unanswered questions about the fate of the long-standing high-tech effort. Differences in opinion could delay or derail tree restoration plans.
“Almost every month, every time we turn around, there are more red flags,” says Sarah Fern Fitzsimmons, chief conservation officer at the American Chestnut Foundation. “If you weren’t really worried, you wouldn’t stop doing this.”
“This is a science-based decision,” she added.
But Andrew Newhouse, director of chestnut restoration at the State University of New York ESF, said his team is working to seek federal approval to begin distributing seeds to the public, but his longtime partner and financial partner He said he is proceeding without a foundation with 5,000 members who support him.
Concerns about how trees in the field will grow are either overdone or can be overcome, he said.The school is It is awaiting green light from the Department of Agriculture and the Environmental Protection Agency.
“We are very interested in moving forward and doing good science, and we do not believe that halting the application altogether is justified,” Newhouse said. “We haven’t seen any risks so far, we haven’t seen any harm to other organisms, and we think it’s really important that we continue to study this and continue to learn. And further research will actually clarify some of these concerns.”
Billions of American chestnuts once covered the canopy of trees from Maine to Mississippi, raining nuts onto the forest floor for human and animal consumption, and providing the straight-grained, rot-resistant wood on which the young American nation was built.
But toward the beginning of the 20th century, an invasive fungus pecked the bark with cankers, cutting off circulation and nearly wiping out the trees. Today, some wild chestnuts are still germinating, but they rarely reach maturity, and scientists believe the tree is “functionally extinct.”
After years of fruitless efforts to use traditional breeding to produce blight-resistant American chestnuts, SUNY ESF scientists have developed a series of genetically modified trees to do so. About 10 years ago, researchers began inserting genes into chestnut DNA that produce enzymes that neutralize chemicals secreted by fungi that help kill and eat wood tissue.
SUNY ESF has advanced the development of one strain, called Darling 58. In this lineage, genes with unknown functions were added to part of the genome. Over the past few years, the research team has distributed the modified chestnuts to other labs for research.
“I’ve thought for years that this would work,” Westbrook said.
But just recently, the American Chestnut Foundation says, some outside researchers began noticing problems with the darling trees they were growing. Some chestnuts were shorter than normal chestnuts. Some showed less resistance to infection than expected. Still others have sprouted curly brown leaves. Mortality rates of genetically modified trees were also high in some plots.
“If it weren’t for the mounting evidence from other trials, we would have considered this a huge failure,” said Jason Holliday, a professor at Virginia Tech, noting that genetically modified chestnuts had higher mortality rates.
The American Chestnut Foundation also raised concerns about SUNY ESF’s interest in ultimately using commercial companies to grow the seeds. The move was intended to help the school expand distribution, but it ran counter to the foundation’s nonprofit mission.
At the University of New England, Thomas Clack was conducting “rapid breeding” of transgenic chestnuts under grow lights, but struggled to produce many plants with two copies of the gene to fight late blight. Was.
They made the discovery this fall after he enlisted the help of University of Maine geneticist Ek Han Tan to analyze the chestnut genome. The plant they were studying wasn’t actually a Darling 58 tree.
Instead, they were conducting research on another chestnut strain called Darling 54, where the gene was inserted into a completely different chromosome, potentially disrupting one of the tree’s existing genes. discovered. Mr. Clack called Mr. Westbrook with the news in late October.
“In a way, it was a little disappointing because I knew so much effort had gone into the 58,” Tan said. The federal government said, “We are glad that we were able to resolve the issue sooner than anyone else and before deregulation.”
Tan teaches a course on genetic engineering and thinks it is a promising solution to bringing back chestnuts, but understands how controversial the technology can be.
“The success or failure of technology depends on public opinion, should we say failure? So you can’t say something isn’t what it is.”
“Science is never smooth,” Clack added. “It’s normal in science to take two steps forward and one step back, but you just keep moving forward.”
In a phone interview, Newhouse, the SUNY ESF director, acknowledged the mix-up but said he didn’t know what happened.
“We don’t know exactly how it happened,” he said. “It must have been around 2016 or so that he swapped labels between the two trees while we were working at the same time.”
At this time, no one knows the exact cause behind the performance issue. We don’t know if that has to do with where the gene is inserted, or simply with the presence of the new gene itself. But the American Chestnut Foundation isn’t looking away from genetic engineering as a potential solution for chestnut restoration.
“This is science,” Fitzsimmons said. “Something happens.” But she is frustrated by SUNY ESF’s lack of candor. The Foundation learned of the breed mix-up not from SUNY ESF, but from researchers in Maine.
“There was no mistake,” she said. “It’s just that we weren’t told about it.”
James R. McKenna, a former U.S. Forest Service tree breeder who managed the Indiana chestnut fields visited by Westbrook, said the entire Darling line has the potential to preserve genetic diversity in trees. I’m still thinking about it.
“54 has a fatal flaw,” McKenna said. “all [the discovery] So it’s really cooling the jet. We don’t want it to be widely distributed. ”
SUNY ESF said it has notified regulators and is amending documents it submitted for approval. Newhouse said experiments his team has already conducted have shown that Darling’s 54 nuts are safe to eat. His team is testing their own trees to see how many genuine Darling 58 trees there are and estimates there are “dozens” left in the school.
USDA spokesman Richard Coker said the agency is “pausing work until we receive additional information from SUNY.”
Newhouse added that he hasn’t observed high mortality rates on his plot, but acknowledged that the transgenic trees are shorter. He said traditional breeding methods could yield taller transgenic trees.
“The question may arise as to whether a short tree or a dead tree is better,” he says. “Height may not be so important if the tree is disease-resistant and can continue to grow.”