Granite Geek: When the GMO chestnut tree gets here, as it probably will, what should we do?

By DAVID BROOKS

Monitor staff

Published: 10-10-2023 10:45 AM

When local folks who have been working to return the glorious American chestnut tree to our forest gather Saturday in Lebanon to celebrate an anniversary, there will be a big question looming overhead.

What should they do when the genetically modified trees arrive?

Mind you, it’s not certain that they will. These trees, developed at the State University of New York, carry a gene common in grasses that neutralizes the fungal toxin that has virtually wiped out the American chestnut. Supporters say they could shrug off chestnut blight and thrive in our woods, bringing back one of the giants of Eastern forests, and they want federal permission to do widespread planting.

But no GMO plant has ever been approved for release willy-nilly, as compared to being used by farmers or researchers. The U.S. Department of Agriculture has given a preliminary nod to the idea but the Environmental Protection Agency is still weighing the pros and cons, perhaps because they’ve never faced a question like this.

“The idea that something would be released into the wild with the intent that it will be set free, that’s new. In the past it has always been about an agricultural purpose,” said Evan Fox, president of the board for the Vermont/New Hampshire chapter of The American Chestnut Foundation.

If I was a betting man, I’d guess that the EPA will give the thumbs up since this is as benign a case of genetic modification as I can imagine. The inserted gene already exists in a slew of wild plant species and because it doesn’t interfere with the life cycle of the fungus – it only neutralizes the toxin released by the fungus – there’s no chance of the blight evolving to evade it.

Not everyone agrees. There’s a large contingent that thinks no GMO should be let free in the wild due to the possibility of unintended consequences. But the payback of returning the chestnut is so great that I suspect it will go ahead.

If so, what then?

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As you may know, the American chestnut was one of the kings of the Eastern woodlands, making up as much as 50% of forests. The abundant nuts from its huge spreading limbs fed wildlife; its rot-resistant, strong and straight-grained wood was prized above all others; and it grew relatively quickly and regenerated easily. It was as close to the perfect tree as could be imagined.

Then a fungus carried on Japanese chestnut trees arrived at the turn of the 20th century and in a few decades the species was all but extinct. Some trees still grow from rootstock, including a few near my home, but when they get old enough to start producing nuts, the fungus attacks, soon killing them off.

Since 1989, The American Chestnut Foundation has been gathering pollen from these remnant trees and using it to cross-breed them with blight-resistant Chinese chestnut trees in hopes of creating a resistant hybrid that looks and acts like the American chestnut. Trees are raised on special farms, including several in New Hampshire and Vermont, but no blight-fighter has been produced.

Enter science.

Researchers at State University of New York College of Environmental Science and Forestry in Syracuse, tired of waiting for nature to accidentally move the right gene(s) around, decided to do it in the laboratory. Work began a decade ago and the resulting strain, called Darling-58, has shown great resistance in controlled environments and is ready for widespread release to see what happens.

Fox said the Chestnut Foundation, which welcomes the GMO tree even though it might render decades of cross-breeding effort pointless, is taking a cautious approach.

“The Foundation is not going to behave in a way that assumes that tree is the end-all,” he said.

Cross-breeding efforts will continue. There’s also a possibility, he said, that some of the first GMO trees would be cross-bred with some of the existing Chinese/American hybrids to see what happens.

“The foundation is assuming it will be beneficial to assume that there are various sources of resistance, some of which have been achieved by breeding, some of which could be achieved by adding this genetic resistance to those bred trees,” he said. “There’s this thinking that there might be such a thing as stacked resistance, and it would be best to continue development of various forms of resistance and see what can be done.”

Rolling out a new tree breed isn’t a quick process since it takes years for trees to reach maturity and see whether they’re actually resistant. Fox pointed to another bottleneck: A shortage of pure American chestnut flowers that can be pollinated to create future generations.

“We have lots of pollen, lots of blight-resistant pollen, but we have very few pure American trees that are flowering. We have lots of female flowers on hybrid trees. The question of what will be pollinated, what won’t be pollinated – that has to be decided,” Fox said.

All this will probably be a lively topic of discussion at the Salt Hill Pub in Lebanon on Saturday, where the Vermont/New Hampshire chapter will celebrate the 40th anniversary of the national American Chestnut Foundation. The celebration runs from 10:30 to 2 p.m.

The conversation might take a bittersweet turn since it’s not unlikely that two or three decades of work creating thousands of hybrid trees will turn out to have been unnecessary. The whole thing could have been done in the lab with a lot less sweaty fieldwork.

On the other hand, the fieldwork has established that cross-breeding doesn’t seem to be the answer, giving more of an incentive to develop and approve GMO. So it was probably necessary no matter what.

Either way, with any luck, in a decade or so, we’ll start to see American chestnut trees showing up in our woods. That would be very nice, indeed.