A Race to Save the Orange by Altering Its DNA

Trees that are infected by disease are cut down and burned in Clewiston, Fla., at groves owned by Southern Gardens Citrus. Richard Perry/ The New York Times  July 27, 2013

“It’s here” was all his grove manager needed to say to force him over to the side of the road.

The disease that sours oranges and leaves them half green, already ravaging citrus crops across the world, had reached the state’s storied groves. Mr. Kress, the president of Southern Gardens Citrus, in charge of two and a half million orange trees and a factory that squeezes juice for Tropicana and Florida’s Natural, sat in silence for several long moments.

“O.K.,” he said finally on that fall day in 2005, “let’s make a plan.”

In the years that followed, he and the 8,000 other Florida growers who supply most of the nation’s orange juice poured everything they had into fighting the disease they call citrus greening.

To slow the spread of the bacterium that causes the scourge, they chopped down hundreds of thousands of infected trees and sprayed an expanding array of pesticides on the winged insect that carries it. But the contagion could not be contained.

They scoured Central Florida’s half-million acres of emerald groves and sent search parties around the world to find a naturally immune tree that could serve as a new progenitor for a crop that has thrived in the state since its arrival, it is said, with Ponce de León. But such a tree did not exist.

An orange from a tree infected with citrus greening, right, is stunted compared with a normal orange. Richard Perry/The New York Times

“In all of cultivated citrus, there is no evidence of immunity,” the plant pathologist heading a National Research Council task force on the disease said.

In all of citrus, but perhaps not in all of nature. With a precipitous decline in Florida’s harvest predicted within the decade, the only chance left to save it, Mr. Kress believed, was one that his industry and others had long avoided for fear of consumer rejection. They would have to alter the orange’s DNA — with a gene from a different species.

Oranges are not the only crop that might benefit from genetically engineered resistance to diseases for which standard treatments have proven elusive. And advocates of the technology say it could also help provide food for a fast-growing population on a warming planet by endowing crops with more nutrients, or the ability to thrive in drought, or to resist pests. Leading scientific organizations have concluded that shuttling DNA between species carries no intrinsic risk to human health or the environment, and that such alterations can be reliably tested.

But the idea of eating plants and animals whose DNA has been manipulated in a laboratory — called genetically modified organisms, or G.M.O.’s — still spooks many people. Critics worry that such crops carry risks not yet detected, and distrust the big agrochemical companies that have produced the few in wide use. And hostility toward the technology, long ingrained in Europe, has deepened recently among Americans as organic food advocates, environmentalists and others have made opposition to it a pillar of a growing movement for healthier and ethical food choices.

Mr. Kress’s boss worried about damaging the image of juice long promoted as “100 percent natural.”

“Do we really want to do this?” he demanded in a 2008 meeting at the company’s headquarters on the northern rim of the Everglades.

Mr. Kress, now 61, had no particular predilection for biotechnology. Known for working long hours, he rose through the ranks at fruit and juice companies like Welch’s and Seneca Foods. On moving here for the Southern Gardens job, just a few weeks before citrus greening was detected, he had assumed his biggest headache would be competition from flavored waters, or persuading his wife to tolerate Florida’s humidity.

But the dwindling harvest that could mean the idling of his juice processing plant would also have consequences beyond any one company’s bottom line. Florida is the second-largest producer of orange juice in the world, behind Brazil. Its $9 billion citrus industry contributes 76,000 jobs to the state that hosts the Orange Bowl. Southern Gardens, a subsidiary of U.S. Sugar, was one of the few companies in the industry with the wherewithal to finance the development of a “transgenic” tree, which could take a decade and cost as much as $20 million.

An emerging scientific consensus held that genetic engineering would be required to defeat citrus greening. “People are either going to drink transgenic orange juice or they’re going to drink apple juice,” one University of Florida scientist told Mr. Kress.

And if the presence of a new gene in citrus trees prevented juice from becoming scarcer and more expensive, Mr. Kress believed, the American public would embrace it. “The consumer will support us if it’s the only way,” Mr. Kress assured his boss.

Workers inspected orange trees and marked the infected ones. Citrus greening has turned up in millions of trees. Richard Perry/The New York Times

Trial trees that withstood the disease in his greenhouse later succumbed in the field. Concerns about public perception and potential delays in regulatory scrutiny put a damper on some promising leads. But intent on his mission, Mr. Kress shrugged off signs that national campaigns against genetically modified food were gaining traction.

Only in recent months has he begun to face the full magnitude of the gap between what science can achieve and what society might accept.

Millenniums of Intervention

Even in the heyday of frozen concentrate, the popularity of orange juice rested largely on its image as the ultimate natural beverage, fresh-squeezed from a primordial fruit. But the reality is that human intervention has modified the orange for millenniums, as it has almost everything people eat.

Before humans were involved, corn was a wild grass, tomatoes were tiny, carrots were only rarely orange and dairy cows produced little milk. The orange, for its part, might never have existed had human migration not brought together the grapefruit-size pomelo from the tropics and the diminutive mandarin from a temperate zone thousands of years ago in China. And it would not have become the most widely planted fruit tree had human traders not carried it across the globe.

The varieties that have survived, among the many that have since arisen through natural mutation, are the product of human selection, with nearly all of Florida’s juice a blend of just two: the Hamlin, whose unremarkable taste and pale color are offset by its prolific yield in the early season, and the dark, flavorful, late-season Valencia.

Because oranges themselves are hybrids and most seeds are clones of the mother, new varieties cannot easily be produced by crossbreeding — unlike, say, apples, which breeders have remixed into favorites like Fuji and Gala. But the vast majority of oranges in commercial groves are the product of a type of genetic merging that predates the Romans, in which a slender shoot of a favored fruit variety is grafted onto the sturdier roots of other species: lemon, for instance, or sour orange. And a seedless midseason orange recently adopted by Florida growers emerged after breeders bombarded a seedy variety with radiation to disrupt its DNA, a technique for accelerating evolution that has yielded new varieties in dozens of crops, including barley and rice.

Its proponents argue that genetic engineering is one in a continuum of ways humans shape food crops, each of which carries risks: even conventional crossbreeding has occasionally produced toxic varieties of some vegetables. Because making a G.M.O. typically involves adding one or a few genes, each containing instructions for a protein whose function is known, they argue, it is more predictable than traditional methods that involve randomly mixing or mutating many genes of unknown function.

But because it also usually involves taking DNA from the species where it evolved and putting it in another to which it may be only distantly related — or turning off genes already present — critics of the technology say it represents a new and potentially more hazardous degree of tinkering whose risks are not yet fully understood.

If he had had more time, Mr. Kress could have waited for the orange to naturally evolve resistance to the bacteria known as C. liberibacter asiaticus. That could happen tomorrow. Or it could take years, or many decades. Or the orange in Florida could disappear first.

Plunging Ahead

Early discussions among other citrus growers about what kind of disease research they should collectively support did little to reassure Mr. Kress about his own genetic engineering project.

“The public will never drink G.M.O. orange juice,” one grower said at a contentious 2008 meeting. “It’s a waste of our money.”

“The public is already eating tons of G.M.O.’s,” countered Peter McClure, a big grower.

“This isn’t like a bag of Doritos,” snapped another. “We’re talking about a raw product, the essence of orange.”

The genetically modified foods (GMO's) Americans have eaten for more than a decade:

Corn, Soybeans, Some Cottonseed oil, Canola oil and Sugar — come mostly as invisible ingredients in processed foods like cereal, salad dressing and tortilla chips/chips.

And the few G.M.O.’s sold in produce aisles — a Hawaiian papaya, some squash, a fraction of sweet corn — lack the iconic status of a breakfast drink that, Mr. Kress conceded, is “like motherhood” to Americans, who drink more of it per capita than anyone else.

If various polls were to be believed, a third to half of Americans would refuse to eat any transgenic crop.

One study’s respondents would accept only certain types: two-thirds said they would eat a fruit modified with another plant gene, but few would accept one with DNA from an animal. Fewer still would knowingly eat produce that contained a gene from a virus.