Efforts to cross the American chestnut with the Chinese chestnut to create a hybrid resistant to bark blistering began as early as the 1930s. These efforts intensified in the 1950s. The American Chestnut Foundation began official work on the hybrid in the 1980s. “If we fast-forward through the 30 years of breeding work, we find that cancer resistance is more complex than we thought,” says Tom Sailey, a forest scientist with the foundation. Scientists now hypothesize that the interaction of up to nine genetic regions could be responsible for the resistance to cortical cancer. This makes breeding a challenge.
US court decides to use genetic engineering
Reproduction also requires many new generations to progress. Each generation takes years. Genetic engineering takes a controversial shortcut to creating a resistant American chestnut. In the 1990s, Charles Maynard and Bill Powell of the State University of New York at Syracuse began this research, using technology that was new at the time. It’s like, Powell says, “Before you go fishing you have to build a boat. We’re just starting to test for genes.” His aha moment came when he learned about a wheat gene that improves tomato resistance to pathogens. The gene produces oxalate oxidase, an enzyme that renders the oxalic acid produced by bark fungi harmless.
In 2014, Maynard and Powell successfully inserted this wheat gene into the chestnut genome. They christened the modified tree “Darling 58” after Herb Darling, a passionate supporter of their work. Trees planted in trial fields in Syracuse have been found to be tolerant of bark blight. Powell is confident that “Darling 58” is also safe, but “Darling 58” is no longer legal. Genetically modified trees raise fear of the unknown.
Who and where can be grown genetically modified crops are subject to strict regulation in the United States. Powell and his colleagues applied for a Darling 58 license for commercial use. It’s the first time authorities have dealt with such a request to release a genetically modified tree into the wild – it would set a precedent for other plant species. “Once they’re in the forest, you can’t take them back. There’s no way to reverse that,” says Ann Peterman of the Global Justice Ecology Project, an organization that campaigns against genetically modified trees.
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