I should look up from the spiders now and then. I did not know what was happening to forests.
Global trade and climate change are poised to make the spread and severity of arboreal plagues and pestilence worse. The hills around Syracuse are silhouetted with pale ash trees slain by emerald-colored borers. Ancient bristlecone pines out West are succumbing to bark beetle outbreaks triggered by rising temperatures. As many as 1 in 6 trees native to the Lower 48 states are at risk of extinction.
I should know. We bought a house 20 years ago that had a yard full of impressive trees, which we’ve watched steadily decline. Every few years it seems the city splashes another one with neon paint and we’re told it has to come down. But there’s hope! Science rides to the rescue, maybe! The article is about the American Chestnut, and how it’s been wiped out by a fungus.
All it takes is one gene.
The fungus infecting chestnut trees thrives by secreting a chemical called oxalic acid, which kills cells and allows the pathogen to feast on the dead tissue. But many other plants, including bananas, strawberries and wheat, avoid that fate by producing an enzyme called oxalate oxidase that breaks down the toxin.
By 2014, Powell and Maynard successfully added the wheat gene to chestnuts and were growing infection-resistant trees. The pair dubbed one line Darling 58, in honor of Herb.
Many plants use oxalate oxidase as a defense mechanism. It catalyzes the oxidation of oxalic acid into CO2 and peroxides — reactive oxygen species. Is that going to have a side effect? I don’t know. Barley makes multiple forms of oxalate oxidase, and it doesn’t seem to harm beer production.
“Making a transgenic tree — I hate to say it like this, but it isn’t that hard,” Newhouse said. The most difficult hurdle for Darling 58, he said, is winning regulatory approval.
Well. This is sort of true. Making transgenic organisms is relatively easy nowadays, EXCEPT…the difficult part is figuring out what gene to use, and since most traits have complex origins, and since the expression of the gene is going to have multiple effects on the organism, it’s difficult to predict all of the consequences. There are good reasons regulatory approval is tough to get.
But in this case, they seem to have found a relatively simple way to confer fungus resistance on a tree, and it’s been tried experimentally, and they have successfully produced healthy, blight resistant chestnut trees. However, I think uncertainty about possible outcomes is a good reason to go slow, and regulatory agencies are doing the right thing by putting the brakes on the process.
There are also bad reasons for resisting the transgenic trees, and there seem to be a lot of people blocking it. Their primary argument is this weird idea that “natural” mechanisms like breeding hybrid trees are somehow “better” than transgenic methods — this is the same reasoning that has led to GMO labeling in our grocery stores, as if somehow the fact that an agricultural scientist has intentionally tweaked a plant is bad, while wholesale, random interbreeding of varieties is more pure. I don’t get it. Don’t people realize that all of the crop plants producing your food have been extensively modified by centuries or millennia of intentional manipulation of their genomes? Everything in the supermarket is a mutant, GMO or non-GMO. I’d argue that the genetically modified plants have undergone less drastic changes than those produced the old-fashioned way.
…Powell countered that crossbreeding transfers far more genes between species. “Genetic engineering is actually a less-risky procedure than a lot of things that we’ve done in the past,” he said. “We are very precise. We’re only moving one, two — just a small number of genes into the tree.”
That the changes are small are not a reason to dismiss regulatory oversight, of course. The reason they can use only one or two genes is that they have specifically selected target genes of very large effect.
Of course, re-creating vast chestnut forests would also be a huge effect.