The Best American Science and Nature Writing 2014
Page 7
AMY HARMON
A Race to Save the Orange by Altering Its DNA
FROM The New York Times
CLEWISTON, FLORIDA—The call Ricke Kress and every other citrus grower in Florida dreaded came while he was driving.
“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. Kress, the president of Southern Gardens Citrus, in charge of 2.5 million orange trees and a factory that squeezes juice for Tropicana and Florida’s Natural, sat in silence for several long moments.
“OK,” 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 Leon. But such a tree did not exist.
“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, 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 GMOs—still spooks many people. Critics worry that such crops carry risks not yet detected, and they 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.
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.
Kress, now sixty-one, 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 that 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 Kress.
And if the presence of a new gene in citrus trees prevented juice from becoming scarcer and more expensive, Kress believed, the American public would embrace it. “The consumer will support us if it’s the only way,” Kress assured his boss.
His quest to save the orange offers a close look at the daunting process of genetically modifying one well-loved organism—on a deadline. In the past several years, out of public view, he has considered DNA donors from all over the tree of life, including two vegetables, a virus, and, briefly, a pig. A synthetic gene, manufactured in the laboratory, also emerged as a contender.
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, 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. 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 GMO 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.
Plunging Ahead
Early discussions among other citrus growers about what kind of disease research they should collectively support did little to reassure Kress about his own genetic engineering project.
“The public will never drink GMO orange juice,” one grower said at a contentious 2008 meeting. “It’s a waste of our money.”
“The public is already eating tons of GMOs,” 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 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. And the few GMOs sold in produce aisles—a Hawaiian papaya, some squash, a fraction of sweet corn—lack the iconic status of a breakfast drink that, 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.
There also appeared to be an abiding belief that a plant would take on the identity of the species from which its new DNA was drawn, like the scientist in the movie The Fly, who sprouted insect parts after a DNA-mixing mistake with a housefly.
Asked if tomatoes containing a gene from a fish would “taste fishy” in a question on a 2004 poll conducted by the Food Policy Institute at Rutgers University, referring to one company’s efforts to forge a frost-resistant tomato with a gene from the winter flounder, fewer than half correctly answered “no.” A fear that the genetic engineering of food would throw the ecosystem out of whack showed in the surveys too.
Kress’s researchers, in turn, liked to point out that the very reason genetic engineering works is that all living things share a basic biochemistry: if a gene from a cold-water fish can help a tomato resist frost, it is because DNA is a universal code that tomato cells know how to read. Even the most distantly related species—say, humans and bacteria—share many genes whose functions have remained constant across billions of years of evolution.
“It’s not where a gene comes from that matters,” one researcher said. “It’s what it does.”
Kress set the surveys aside.
He took encouragement from other attempts to genetically modify foods that were in the works. There was even another fruit, the “Arctic apple,” whose genes for browning were switched off to reduce waste and allow the fruit to be more readily sold sliced.
“The public is going to be more informed about GMOs by the time we’re ready,” Kress told his research director, Michael P. Irey, as they lined up the five scientists whom Southern Gardens would underwrite. And to the scientists, growers, and juice processors at a meeting convened by Minute Maid in Miami in early 2010, he insisted that just finding a gene that worked had to be his company’s priority.
The foes were formidable. C. liberibacter, the bacterium that kills citrus trees by choking off their flow of nutrients—first detected when it destroyed citrus trees more than a century ago in China—had earned a place, along with anthrax and the Ebola virus, on the Agriculture Department’s list of potential agents of bioterrorism. Asian citrus psyllids, the insects that suck the bacteria out of one tree and inject them into another as they feed on the sap of their leaves, can carry the germ a mile without stopping, and the females can lay up to eight hundred eggs in their one-month life.
Kress’s DNA candidate would have to fight off the bacteria or the insect. As for public acceptance, he told his industry colleagues, “We can’t think about that right now.”
The “Creep Factor”
Trim, silver-haired, and described by colleagues as tightly wound (he prefers “focused”), Kress arrives at the office by 6:30 each morning and microwaves a bowl of oatmeal. He stocks his office cabinet with cans of peel-top Campbell’s chicken soup, which he heats up for lunch. Arriving home each evening, he cuts a rose from his garden for his wife. Weekends he works in his yard and pores over clippings about GMOs in the news.
For a man who takes pleasure in routine, the uncertainty that marked his DNA quest was disquieting. It would cost Southern Gardens millions of dollars just to perform the safety tests for a single gene in a single variety of orange. Of his five researchers’ approaches, he had planned to narrow the field to the one that worked best over time.
But in 2010, with the disease spreading faster than anyone anticipated, the factor that came to weigh most was which could be ready first.
To fight C. liberibacter, Dean Gabriel at the University of Florida had chosen a gene from a virus that destroys bacteria as it replicates itself. Though such viruses, called bacteriophages (“phage” means to devour), are harmless to humans, Irey sometimes urged Kress to consider the public relations hurdle that might come with such a strange-sounding source of the DNA. “A gene from a virus,” he would ask pointedly, “that infects bacteria?”
But Kress’s chief concern was that Gabriel was taking too long to perfect his approach.
A second contender, Erik Mirkov of Texas A&M University, was further along with trees he had endowed with a gene from spinach—a food, he reminded Kress, that “we give to babies.” The gene, which exists in slightly different forms in hundreds of plants and animals, produces a protein that attacks invading bacteria.
Even so, Mirkov faced skepticism from growers. “Will my juice taste like spinach?” one asked.
“Will it be green?” wondered another.
“This gene,” he invariably replied, “has nothing to do with the color or taste of spinach. Your body makes very similar kinds of proteins as part of your own defense against bacteria.”
When some of the scientist’s promising trees got sick in their first trial, Kress agreed that he should try to improve on his results in a new generation of trees, by adjusting the gene’s placement. But transgenic trees, begun as a single cell in a petri dish, can take two years before they are sturdy enough to place in the ground and many more years to bear fruit.
“Isn’t there a gene,” Kress asked Irey, “to hurry up Mother Nature?”
For a time, the answer seemed to lie with a third scientist, William O. Dawson at the University of Florida, who had managed to alter fully grown trees by attaching a gene to a virus that could be inserted by way of a small incision in the bark. Genes transmitted that way would eventually stop functioning, but Kress hoped to use it as a stopgap measure to ward off the disease in the 60 million citrus trees already in Florida’s groves. Dawson joked that he hoped at least to save the grapefruit, whose juice he enjoyed, “preferably with a little vodka in it.”
But his most promising result that year was doomed from the beginning: of the dozen bacteria-fighting genes he had then tested on his greenhouse trees, the one that appeared effective came from a pig.
One of about 30,000 genes in the animal’s genetic code, it was, he ventured, “a pretty small amount of pig.”
“There’s no safety issue from our standpoint—but there is a certain creep factor,” an Environmental Protection Agency official observed to Kress, who had included it on an early list of possibilities to run by the agency.
“At least something is working,” Kress bristled. “It’s a proof of concept.”
A similar caution dimmed his hopes for the timely approval of a synthetic gene, designed in the laboratory of a fourth scientist, Jesse Jaynes of Tuskegee Unive
rsity. In a simulation, Jaynes’s gene consistently vanquished the greening bacteria. But the burden of proving a synthetic gene’s safety would prolong the process. “You’re going to get more questions,” Kress was told, “with a gene not found in nature.”
In the fall of 2010, an onion gene that discouraged psyllids from landing on tomato plants was working in the Cornell laboratory of Kress’s final hope, Herb Aldwinckle. But it would be some time before the gene could be transferred to orange trees.
Only Mirkov’s newly fine-tuned trees with the spinach gene, Kress and Irey agreed, could be ready in time to stave off what many believed would soon be a steep decline in the harvest. In the fall of 2010, they were put to the test inside a padlocked greenhouse stocked with infected trees and psyllids.
The Monsanto Effect
Kress’s only direct brush so far with the broader battle raging over genetically modified food came in December 2010, in readers’ comments on a Reuters article alluding to Southern Gardens’ genetic engineering efforts.
Some readers vowed not to buy such “frankenfood.” Another attributed a rise in allergies to genetic engineering. And dozens lambasted Monsanto, the St. Louis–based company that dominates the crop biotechnology business, which was not even mentioned in the article.
“If this trend goes on, one day, there will be only Monsanto engineered foods available,” read one letter warning of unintended consequences.
Kress was unperturbed. Dozens of long-term animal feeding studies had concluded that existing GMOs were as safe as other crops, and the National Academy of Sciences, the World Health Organization, and others had issued statements to the same effect.