Genetically Engineering an Icon: Can Biotech Bring the Chestnut Back to America's Forests?

Powell reached out to one of the authors of that paper, Randy Allen at Texas Tech, who mailed him copies of the gene in a test tube. Back at the SUNY-ESF lab, they began by putting them into hybrid poplar (they still at that point were unable to genetically engineer chestnut). That worked, and they were able to increase the poplar's resistance to another fungal pathogen. "That kind of showed us, oh, this is a good gene to use," Powell said.

Over the next few years, Powell, his colleagues at ESF, and scientists at labs around the country made incremental progress toward their dream of a blight-resistant transgenic chestnut. In the early 2000s, they were first able to genetically engineer a chestnut embryo; the related paper was published in 2006 -- the same year the first transgenic chestnut was planeted outside of the lab. Following that they developed a line of chestnuts called Darling 4, which seems to be a bit less resistant to the blight than Chinese chestnuts, but still much better than a regular American chestnut. Last summer, they planted one of those trees at the New York Botanical Garden, not far from where the blight was first discovered.

The Darling 4 gets planted at the New York Botanical Garden. (courtesy of William A. Powell)

But they wanted even higher levels of resistance yet, and now they think they might have done it: a transgenic line of chestnuts, more resistant to the blight than even the Chinese trees. The team, lead by then-graduate student Amelia Bo Zhang, published their results in Trangenic Research in March. Earlier this month, they planted these trees at the Lafayette Road Experiment Station -- the first American chestnuts on this Earth that are highly resistant to the blight.

"Doing research on trees is just very difficult," Zhang told me. "The trees have very long lifespans. And it took a lot of researchers so many years to get to the point where we are today." Powell estimates that more than 50 different people at his and Maynard's lab have worked on this project over the last 23 years.

Powell is quick to emphasize that these results are preliminary, based on "leaf assay tests" which take place in the lab and are performed on small plants. "Working with trees is really hard because you have to get it to grow to a certain size. We really need to get it to be about two to three years old to do the final test to confirm that it is truly resistant," he said.

So for now, those little saplings just need to grow. As they do, the lab's going to keep at work, hunting for more genes that could provide resistance to the fungus, in the hopes that they can eventually design plants with a more lasting resistance, one that the fungus cannot mutate to overcome.

In the long run, Powell would like to see resistant transgenic trees crossbred with the few surviving wild trees, in the hopes of building up a diverse population of trees, all carrying the wheat gene. With those trees, he'd like to begin a restoration program, planting the trees in former mines (where the soil is unnaturally acidic) and passing the trees out to the general public for reintroduction to the eastern forests, once the trees get the necessary approval from the USDA, the EPA, and, since chestnuts provide food, the FDA. The chestnut isn't the first transgenic tree to go through a regulatory process -- transgenic plums and papaya have both been approved for agriculture -- but, when it comes to reintroducing a genetically engineered tree into the wild, Powell says the chestnut program is "unique."

All of which is to say, we may soon find ourselves in the position of being able to engineer, through genetic manipulation, an ecosystem more healthy and diverse than it would be if we just left it alone; with 21st-century biotechnology, we could recreate something more like the forests of old. What are the risks we would undertake in doing so? Will our careful regulatory process protect us from upsetting our forests once again?

When Robert Frost asked, in 1936, "Will the blight end the chestnut?" he thought the answer no. The trees would keep "smouldering at the roots / And sending up new shoots / Till another parasite / Shall come and end the blight." Natural processes would send the system back into balance. The poem is called "Evil Tendencies Cancel."

But of course, that hasn't been the case. The eastern forests have returned, thrived even, in recent decades, but they've done so without the iconic chestnut. In the end, if Amelia Bo Zhang's trees do as well as she and Powell hope, it will be the hand of science, not a newfound parasite, that will right the fallen.


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Rebecca J. Rosen is a senior editor at The Atlantic, where she oversees the Business Channel. She was previously an associate editor at The Wilson Quarterly.

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