The African Sunset petunia is one of the genetically engineered varieties that U.S. officials are asking breeders to destroy.

F. D. RICHARDS/FLICKR (CC BY-SA 2.0)

How the transgenic petunia carnage of 2017 began

Two years ago, plant biologist Teemu Teeri was walking by a train station in Helsinki when he noticed some vivid orange petunias in a planter. The flowers reminded Teeri, who has studied plant pigments at the University of Helsinki, of blooms created in a landmark gene-engineering experiment some 30 years earlier. As far as he knew, those flowers never made it to market. But he was curious, and he stuck a stem in his backpack.

Now, that chance encounter has ended up forcing flower sellers on two continents to destroy vast numbers of petunias. Teeri ultimately confirmed that the plants contained foreign DNA, and he tipped off regulators in Europe and the United States, who have identified other commercial strains that are genetically engineered (GE). Although officials say the GE petunias pose no threat to human health or the environment—and likely were unknowingly sold for years—they’ve asked sellers to destroy the flowers, because it’s illegal to sell them in the United States and Europe without a permit.

Ironically, proposed revisions to U.S. biotechnology rules now under discussion might have exempted the harmless petunias from regulation. But the petunia carnage highlights the growing complexity of regulating GE plants, which have a long history of showing up where they aren’t allowed and can be hard to track.

A prominent experiment

Purveyors of petunia varieties with names such as Trilogy Mango and African Sunset were likely unaware that orange-pigmented petunias are the product of a prominent biotechnology study. In a 1987 Nature paper, a team led by plant geneticist Peter Meyer, then with the Max Planck Institute for Plant Breeding Research in Cologne, Germany, showed that inserting a maize gene into a petunia enabled it to produce the pigment pelargonidin and take on a salmon color. The 30,000 petunias that the team planted in a trial were the first transgenic plants ever released into the field in Germany, notes Meyer, now at the University of Leeds in the United Kingdom. Public resistance was fierce at the time, he recalls: “The term transgenic was basically used synonymously with toxic.”

The controversy didn’t deter S&G Seeds, an affiliate of the Dutch seed company Zaadunie, from licensing the technology. And in 1995 it reported creating petunias with more stable gene expression—and a vivid orange color—fit for commercial breeding. Another company, Rogers NK, also collaborating with Zaadunie, won clearance from U.S. regulators for an orange petunia field trial in Florida. But the companies apparently never commercialized the variety, Meyer says—whether because of unfriendly public perceptions, regulatory hurdles, or simple economics. “I had almost forgotten about it.”

Because he knew that history, Teeri was initially flummoxed by the orange blooms he saw at the Helsinki train station. “This petunia was sort of cheating me, fooling my eye,” he recalls. “There must be a yellow pigment on top” that created the orange appearance, he thought. But months later his tests revealed a DNA insert matching what the 1987 paper described. Other orange petunia seed varieties he bought online also had the tell-tale alterations.

Teeri then made a decision he now regrets: spilling the beans to a former Ph.D. student who had taken a job as a regulator at the Finnish Board for Gene Technology. “I told too much,” he says. “I should have asked a hypothetical question,” about what would happen if regulators discovered GE petunias that had not gone through the proper regulatory channels. On 27 April, Evira, Finland’s food safety body, called for eight petunia varieties to be removed from the market. Other European nations also began investigations.

Teemu Teeri

Veikko Somerpuro

By 2 May, the U.S. Department of Agriculture’s (USDA’s) Animal and Plant Health Inspection Service (APHIS) was on alert. It worked with breeders to perform a standard GE screen, searching suspect petunias’ DNA for the cauliflower mosaic virus sometimes used to control the expression of an inserted gene. Like several early workhorses of genetic engineering, the virus is officially considered a “plant pest,” and plants containing its DNA are subject to APHIS regulation. The testing has so far revealed 10 varieties of GE petunia, and 21 others have been “implicated as potentially GE.” In a guidance to the industry, it gave growers and sellers several options: Incinerate, autoclave, bury, compost, or dispose of the plants in a landfill.

The doomed petunias may number in the thousands, though industry groups couldn’t provide precise estimates. Some companies appear to have unwittingly purveyed the plants for nearly a decade, says Michael Firko, deputy administrator of APHIS’s Biotechnology Regulatory Services division in Riverdale, Maryland. A member of his team even discovered the orange flowers in a centerpiece at a graduation party earlier this month. “She was tempted to take a sample, but she didn’t want to destroy the nice floral display,” Firko says.

Wayward plants

This is far from the first discovery of unauthorized GE plants. Aventis CropScience’s StarLink GE corn variety, approved in the United States only for use in animal feed, popped in up in commercial taco shells in 2000, forcing a nationwide recall of hundreds of supermarket products. When GE wheat appeared on an Oregon farm in 2013, USDA launched an investigation that linked the herbicide-resistant crop to agricultural chemical giant Monsanto. The event caused several Asian countries to postpone imports, though the agency ultimately found no evidence that GE wheat had entered the commercial market.

In this case, USDA says it isn’t planning to pursue or punish flower firms for what seems to be an honest mistake with few implications for international trade. And it’s also unlikely to do the difficult forensics that would be necessary to trace the links between the modern petunia varieties and their ancestors. Biotech conglomerate Sandoz, which owned Zaadunie when the GE petunia was first developed, merged to form Novartis in 1996, which then joined its agribusiness with AstraZeneca’s in 2000 to form Syngenta.

“I don’t know what happened between 1987 and today, but somewhere along the line, it would seem that somebody lost sight of the fact that the original color breakthrough in question here had been achieved through genetic modification,” says Craig Regelbrugge, senior vice president in the Washington, D.C., office of the trade group AmericanHort. And companies often use their competitors’ varieties to develop new ones, he notes. “Nobody would have ever thought to check” for foreign genes, he says.

Challenges to come

The petunias are likely an isolated case—not harbingers of more stealthy GE flower discoveries to come, Regelbrugge says, but as genetic engineering becomes more common in the industry, seed companies may begin to track GE varieties more carefully.

Detecting engineered plants is only likely to get harder. Varieties made with newer gene-editing technologies—such as CRISPR, for example—may not contain any definitive evidence of tinkering. Meanwhile, APHIS is mulling draft regulations—still in early stages of public comment—under which the presence of plant pest DNA alone would no longer trigger oversight. Strict regulation of a product based simply on the method that produced it is “quite irrational,” says Teeri, who hopes to publish a paper on his discovery of the GE petunias.

Teeri also wonders whether the petunias will offer a more sympathetic emblem of genetically modified organisms that have aroused strong opposition in both the United States and Europe. Unlike large-scale agricultural crops engineered to benefit farmers, orange GE petunias focus on “a consumer trait,” he says. “The consumer has chosen to buy it because it’s beautiful.”

U.S. consumers aren’t being asked to rip the GE petunias from their yards and planters, but even those that evade destruction won’t survive the winter in most parts of North America, so are likely to be history by next spring.

Correction, 5/26/17, 2:58 p.m.: As a result of an editor’s error, petunias were identified as an annual plant. According to Eulalia Palomo of the website hunker.com, petunias are “often referred to and grown as annuals” but “are technically warm climate perennials. They grow year round in U.S. Department of Agriculture plant hardiness zones 10 through 11.”