|Researchers are working to develop a blight-resistant strain of the American chestnut tree, which has been all but wiped out. Seen here are Andy Newhouse (L) and Jason Corwin (R), at the American Chestnut Research and Restoration Project at SUNY, surface-sterilizing and extracting embryos from American chestnut burs in preparation for asexual propagation. What if the best way to bring back this tree is via genetic engineering?|
How far out on a limb would you go to bring back an icon of the American forest?
First, a Look at GMOs
Genetically modified organisms or GMOs can engender strong passions and stimulate spirited debate; at least they do in my family. Whenever we get together and the subject comes up, a lively discussion ensues, sometimes erupts, between my kids (well, kids to me even though they're on the other side of 30) and me. To them, GMOs are plain bad.
The long-practiced art of artificial selection is one thing; but creating a transgenic organism by tinkering with its genetic makeup is, in their minds at least, something else entirely. Something that could unleash a vegetative (see here, here, here and here) or animalistic (see here, here, here, here and here) Frankenstein that could wreak havoc on the environment and possibly our food. Theirs is a sort of "Don't mess with Mother Nature" imperative.
Besides, they continue, look what the Big Ag companies are doing with GMO technology. Producing strains of crops that allow farmers to use huge quantities of pesticides that poison the environment (see video) and our food and in the end only speed the evolution of pesticide-resistant superweeds (see here, here, here and here) and pests. (They can also turn the small farmer and the subsistence farmer into farmers with a bunch of dead crops, as this film about Peruvian farmers documents.)
To me, the issue is not so black and white. We have been genetically engineering crops for millennia, albeit not using modern molecular biology but by crossbreeding and artificial selection. The methods may be different, but the result is much the same: an organism whose genetic makeup has been altered by humans to suit human needs.
Is there any difference between an organism that has been designed through the time-honored hybridization method and one designed using modern molecular biology? I don't think so. Genetic engineering gives biologists a much larger tool chest of genetic material to operate with but in the final analysis an organism is determined by its genetic makeup not how that makeup was constructed.
And as far as the Big Ag stuff goes: just because some companies use GMO technology to bad ends does not mean the technology is a priori bad.
The debate eventually ends because of exhaustion and without any resolution, let alone a meeting of the minds. I've often wondered if our inability to find common ground on GMOs is that my anti-GMO offspring are conflating GMOs with their perceived evils of Big Ag and their concerns for our sustainable foods. Wouldn't it be great if there were an issue that purely focused on the benefits and risks of GMOs alone? Well, I think I've found one: efforts to bring back the American chestnut tree.
Remember the American Chestnut?
|The American chestnut was once one of the country's great trees. (Forest Historical Society)|
There was a time when the American chestnut tree "reigned over 200 million acres of eastern woodlands from Maine to Florida, and from the Piedmont west to the Ohio Valley. ... An estimated 4 billion American chestnuts, 1/4 of the hardwood tree population, grew within this range." See range map. (Remember "Under a spreading chestnut-tree/The village smithy stands" from 1840?)
These were magnificent trees --150 feet tall -- with a bountiful crop of chestnuts that supported wildlife and provided wood timber ideally suited for items ranging from fence posts to musical instruments (which reminds me of another ode to the chestnut circa the 1950s: "perfect/as a violin that has just/been born in the treetops/and falls/offering the gifts locked inside it,/its hidden sweetness").
But in the 20th century all the grandeur and natural poetry of this once mighty tree changed. A fungus imported with the Asian chestnut (called chestnut blight or Cryphonectria parasitica) virtually wiped out mature American chestnuts from the American landscape by the 1950s. (See here [pdf] for fuller history.)
Seedling American chestnut trees still appear in the forest, but "survive primarily as stump sprouts and small understory trees, which are often killed back to the ground (by the blight) before flowering" and generating chestnuts. Sources here [pdf] and here. (For more on the American chestnut see here, here [video] and here.)
Two Efforts to Bring the Chestnut Back
Fortunately, a comeback may be in the works for the American chestnut. There are now at least two groups working to develop a blight-resistant strain of the American chestnut that can be reintroduced into the forests of the eastern United States with a chance of survival.* (Whether such blight-resistant trees will propagate is uncertain as much of the niche once occupied by the American chestnut is now filled by oaks.)
|The American Chestnut Foundation, supported by the U.S. Forest Service, is working to bring back the American chestnut through a process called the backcross method. Pictured is a planting site. (U.S. Forest Service)|
The American Chestnut Foundation is pursuing a traditional hybridization approach. They begin by crossbreeding an American chestnut with a Chinese chestnut, identify those that are most resistant to blight, and continue to crossbreed with American chestnuts and selecting for blight resistance.
The group has now developed a new strain of chestnut that is genetically 15/16ths American chestnut and 1/16th Chinese chestnut, with that last 1/16th hopefully carrying the Chinese chestnuts' blight-resistant genes. (For more details on this work see my earlier post and this Americanforests.org article.) The American Chestnut Foundation has a crop of these 15/16ths American chestnuts and has begun planting them in the wild. Will they make it? We'll have to wait and see.
The other group, at the College of Environmental Science and Forestry of the State University of New York in Syracuse, is using molecular biology. In the American Chestnut Research and Restoration Project, scientists are attempting to produce a genetically modified, transgenic strain of American chestnut that is resistant to the Chinese blight. To do so, as Helen Thompson reports in the journal Nature, they have taken genes "from Chinese chestnuts as well as plants such as wheat, peppers and grapes" and inserted them into the genetic sequence of an American chestnut.
The group has now planted some 600 of the genetically modified trees in field trials and a variety with a gene from wheat is showing signs of blight resistance. As the New York Times reports, because the trees from the American Chestnut Research and Restoration Project are transgenic, they "can be raised only in orchards and other places where there is no potential for their pollen to fertilize other trees." Presumably a variety of regulatory hurdles would need to be cleared before these trees could planted in the wild. (See here [pdf] and here.)
So there you have it, two groups with noble intentions aimed at restoring a majestic tree -- one using traditional methods and the other genetic engineering. Is the traditional method better? Is the GMO approach wrong? What if the traditional method doesn't work and genetic engineering ends up being our only option for bringing back the American chestnut? Should we forgo the possibility of bringing back the American chestnut tree because of a fear that genetic engineering could produce a tree Frankenstein?
I asked one of my kids that. He thought a moment and said, "A GMO version of the American chestnut? Risky." I was going to push him on this, but then I thought of all the times in his youth when I had admonished him to "be safe." Maybe a little caution wouldn't be such a bad thing.
* Other researchers are taking a completely different tack, developing viruses that attack the Chinese blight fungus itself. If successful, such viruses could be injected into infected trees to save them. One such researcher is Don Nuss at the University of Maryland in College Park who is using a genetically modified fungus to carry the virus into the tree. A project in New Jersey [pdf] is taking "chestnuts from trees that have demonstrated resistance to blight and has these seeds grown to seedlings at Bayside State Prison through a cooperative program. The seedlings are then provided to landowners with appropriate planting areas to promote restoration."
Post updated on 7/19/2013, 5:15 PM:
The post was corrected to remove the picture of a diseased elm tree mislabeled as an American chestnut tree.