Genetically modified agriculture holds both the promise of drought- and virus-resistant crops and the peril of unraveling the natural food chain. But like it or not, it’s one genie that’s already out of the bottle.
The plum trees growing in an orchard in Kearneysville, West Virginia, look like any conventional variety. Arranged in neat rows, verdant oblong leaves crowding their unkempt branches, they produce respectable yields of sweet purple-black fruit each year. Yet they’re quite different in one respect: These trees aren’t likely to succumb to the devastating plum pox virus (PPV). That’s because they’ve been genetically engineered to resist the disease, which has infected 100 million trees in Europe and surfaced in Pennsylvania, Michigan, and New York during the past 12 years.
“We couldn’t find a gene for plum pox resistance in any plums, so we turned to genetic engineering,” says Ralph Scorza, a horticulturist and lead scientist at the USDA’s Appalachian Fruit Research Station, walking through the one-acre HoneySweet plum orchard. “We’ve had test-field plantings in Europe since 1996 and the U.S. since 1995, and we’ve never had a single tree infected.”
Like all genetically engineered, or GE, crops—also called transgenic or genetically modified—HoneySweet plums contain foreign DNA that alters them in a desirable way. Beginning in the early 1990s Scorza and his colleagues isolated a gene from the virus, inserted it into a bacterium, and then introduced that into a single plant cell. Adding hormones spurred that cell to grow into a PPV-resistant tree.
Eight years after being submitted for approval, the transgenic plant will clear final regulatory hurdles this year. Not that Scorza expects farmers to start planting it anytime soon. Instead he envisions breeders using it to develop PPV-resistant varieties adapted to their region in case there’s an outbreak. Pennsylvania spent ten years and tens of millions of dollars eradicating plum pox by cutting down infected trees, and New York is still battling the virus on a small scale. The real fear, explains Scorza, is that it will hit California, which produces all U.S. prunes and half of the world’s supply. Furthermore, all stone fruits, including peaches and apricots, are susceptible. “It’s preemptive,” says Scorza. “Right now growers don’t need HoneySweet because plum pox is under control. But if it blows up here, farmers can start planting resistant varieties.”
Safeguarding orchards might also protect wild plums. “We don’t know what would happen if it got into those trees,” Scorza adds. “Would they die? And what would that loss of fruit mean for birds or other animals? We don’t want to get movement from agriculture into the wild.”
To date the USDA, one of three regulatory agencies, has approved more than 70 applications for transgenic plants created for commercial use, although HoneySweet is only the second approved GE fruit tree, after a virus-resistant papaya. As with its predecessors, HoneySweet has raised environmental red flags. The transgenic pollen could be harmful to wild pollinators or possibly pollinate non-GE trees. “My activist friends might not like to hear me say this, but it’s not something I’d lose sleep over,” says Doug Gurian-Sherman, senior scientist with the Union of Concerned Scientists, a nonprofit alliance of more than 250,000 citizens and researchers. “Yes, there are risks. But I’m more concerned about other GE crops in the pipeline.”
When it comes to genetic engineering, a knee-jerk reaction is more common than Gurian-Sherman’s nuanced take. On one extreme are groups like Greenpeace, which considers transgenic crops “genetic pollution.” On the other is U.S. Agriculture Secretary Tom Vilsack, who calls agricultural biotechnology, including genetic engineering, a “powerful tool that can be used to boost agricultural productivity.” Vilsack’s support of genetic engineering was clear in January, when he opted against a controversial proposal that would have restricted GE alfalfa planting and protected organic alfalfa farmers from potential contamination. Instead, he said the USDA would authorize unrestricted commercial cultivation of the plant, although he assured the public that his department would work to ensure that non-bioengineered seeds remain available to farmers.
What’s certain is that plants and animals awaiting approval hold both promise and peril. The promise is intriguing. Monsanto’s drought-tolerant corn, for instance, might withstand the drier conditions climate change is expected to cause. Then there’s the South Dakota biotech company whose cattle are resistant to mad cow disease; an “Enviropig” that produces low-phosphorous manure (which could reduce water pollution from industrial hog farms); and another pig that produces omega-3, so consumers could get their dose of heart-healthy fatty acids from bacon instead of fish oil or flaxseed.