Can the nearly extinct American chestnut, once a mainstay, be revived?

This story was first published on March 29, 2016.

They were among New Jersey's tallest trees, majestically rising 120 feet from the forest floor. Their rot-resistant wood was prized to make shingles, railroad ties, telegraph poles -- and coffins. Their nuts, which fell with reliable abundance each fall, not only provided food for wildlife, but also served as a cash crop for some people, who collected and sent the nuts to New York and other cities, where they were roasted and sold on street corners.

American chestnuts sometimes made up half the trees in a given forest. At their peak, they numbered as many as 4 to 5 billion from Maine to Georgia. The tree was memorialized in American culture, through the poems of Longfellow, the writings of Thoreau and the lyrics of the classic Christmas carol made famous by Nat King Cole.

But today, the species is nearly wiped out.

Since about 1900, the American chestnut has been attacked relentlessly by a fungus that was introduced when Americans first imported Asian varieties of the tree. The fungus produces cankers on a tree and kills it down to the soil. The roots may survive and send up new shoots, but soon enough, the fungus will reassert itself and the sapling dies back. Eventually the roots lack the energy to produce any more shoots.

Over several decades, nearly all chestnut trees were killed off -- or cut down in a failed attempt to slow the spread of the disease.

"We see chestnut trees in the woods when hiking, but they're always very small, only the size of saplings," said Deedee Burnside of Waldwick, who has helped track down trees on the New Jersey Forest Service list of the state's largest trees. She said she has seen chestnut saplings in the Ramapo Mountains, in Ringwood State Park and in Sussex County. "But they're always just small saplings," Burnside said.

Yet there might be hope for a renaissance of the American chestnut -- or at least a scientifically altered version of the species.

An experimental stand of chestnuts, planted six years ago by a research team from Rutgers University and still only a few feet taller than the researchers themselves, grows in an open area of a wooded plot in Somerset County.

The Rutgers team partnered with the American Chestnut Foundation, which provided the seeds. Some in the experimental stand are pure American chestnuts, some are pure Chinese chestnuts, and the rest represent five families of hybrids -- American chestnuts crossed with Asian chestnuts that have some natural resistance to the fungus. The Rutgers team has been monitoring the trees for survival and performance.

In a separate effort, William Powell and Chuck Maynard, researchers at the State University of New York's College of Environmental Science and Forestry, are filing this year with federal regulators for permission to distribute a blight-resistant strain of American chestnut they produced using a more controversial process -- bioengineering. If they get the approvals, they hope to start delivering specimens to nurseries for the general public.

"This could be one of the most important trees in the United States," Powell said of the chestnut. "And it has become ingrained in our culture."

Think "chestnuts roasting on an open fire" and all of that. (The chestnuts roasted on city streets these days are usually imports from Italy, China and Korea.)

In the mid-1800s, Henry David Thoreau described roaming the Massachusetts woods to collect chestnuts with a bag on his shoulder and a stick to open the nut's shell, a spike-adorned burr. A large chestnut tree grew behind his house. He wrote that when in flower, it was "a bouquet which scented the whole neighborhood." He called the nuts "a good substitute for bread."

In fact, poor residents of Appalachia ground the nuts into a flour to make "downbread," so called because it contained no gluten and therefore didn't rise. Native Americans had used the nuts in a similar way.

Though virtually no tall chestnut trees remain in North Jersey, their former abundance is reflected in the names of our roadways. In Bergen and Passaic counties, there are at least 32 Chestnut Streets, eight Chestnut Avenues, four Chestnut Places, three Chestnut Drives and two Chestnut Courts.

Chestnut Ridge is a community in Montvale. Chestnut Hill is a Passaic assisted-living facility located, naturally, on Chestnut Street.

Burnside has seen chestnut woodwork around windows and doors in some older North Jersey homes. "It's usually dark-stained, not painted," she said.

The state list of the largest trees for each species, last updated in 2013, identifies the biggest known American chestnut as a specimen on Parson's Pond Drive in Franklin Lakes. The tree is listed at 65 feet tall, with a crown spread of 49 feet, and a trunk circumference of more than 6 feet.

When Burnside tried to track the tree down a few years ago, she couldn't find it.

The effort by Rutgers to study a protected stand of American chestnuts and American-Asian hybrids is taking place at Duke Farms in Somerset County. Workers removed stands of Norway maple and other invasive trees from the grounds several years ago, leaving gaps in the forest. The Rutgers research team, led by Brad Hillman, a plant pathologist and biologist, decided to use those gaps to plant chestnut trees. In November 2010, they planted 270 saplings that had been grown from seed in a greenhouse.

So far, none are showing signs of blight, said Christina Kaunzinger, a senior ecologist at Rutgers.

Some died, but not from blight. The first winter after planting, two of the plots flooded and then froze, killing the seedlings off. Some saplings were clipped by a groundhog. "He took down five trees in a row," Kaunzinger said.

Overall, though, they're doing well. Some are starting to produce nuts -- but only in the sunniest locations, and only the Chinese varieties. Whether the trees will remain blight-free remains to be seen. "All tree projects are long term," Kaunzinger said, laughing.

The work that Powell and Maynard are doing at SUNY may have even broader implications. They have bioengineered a strain of chestnut tree that leaves virtually the entire wild American chestnut genome intact -- but adds particular genes from a wheat plant, which enables the tree to neutralize the fungus that causes chestnut tree blight.

"It's far less disruptive to the original chestnut genome than hybrid breeding when crossing the American chestnut with Asian varieties," Powell says. Asian chestnuts are far smaller than the American species, so even hybridized varieties won't grow to the heights of the American chestnut. Powell's bioengineered variety, though, shouldn't have that disadvantage.

Moving genes has been essential to the evolution of all species, Powell said. Gene transfer between species occurs in nature and in our bodies.

To get the wheat genes into the chestnut tree, Powell and his team first insert the genes into an agrobacterium, which then gets inserted into the plant's cells. The same organism that Powell's team used to insert the wheat gene has also modified plants in the wild. Sweet potato varieties we eat today were genetically modified by the same bacterium 8,000 years ago, said Powell, a plant pathologist.

Powell and Maynard have been growing their bioengineered chestnut saplings for 16 years at several sites, including one near Buffalo and another in Westchester County, N.Y. They also have a few trees at the New York Botanical Garden in the Bronx.

They are now preparing to submit their work to federal agencies for regulatory review. In the meantime, they continue to grow their strain of chestnut, and hope to have 10,000 saplings ready to distribute by the time they receive federal approval.

They do not have a patent on the variety they have developed, and plan to sell them at cost to the general public in collaboration with nurseries. They will also likely work with state and federal forest services to plant the new variety in the wild.

The project is the first to seek approval for a transgenic plant to save a species and restore a forest's ecology.

"We'd be blazing a trail," Powell said. He said the same technology could be used to help protect other species facing degradation from invasive insects and disease, such as ash trees, hemlocks and oaks out west.

"We need to be able to use these tools to help our forests, which are under attack," Powell said.