Banana

by Dan Koeppel

  It wasn’t that Swennen didn’t believe his bananas could, eventually, have these qualities. But, as with all conventional banana breeding before and after, it was taking too long to get results. “That’s the banana’s drawback—to get a real, wide-scale evaluation, it takes years.” With Black Sigatoka and other banana diseases advancing, time was something these tiny villages, and the rest of the world, was running out of.

  In 1993 Swennen returned to Belgium. He still misses the adventure of the field, but he now believes that conventional breeding methods just won’t cut it—that saving the banana is something that can only be accomplished in the lab.

  CROSSBREEDING AND BIOTECHNOLOGY are both forms of genetic manipulation. The first has been effective and widespread for thousands and thousands of years. Changing life-forms by directly manipulating their DNA, however, is such a new technology that most scientists believe only a tiny fraction of what needs to be understood about it has so far been discovered. Even so, industrial agriculture is exposing the public to such technologies (often without disclosure) with daily frequency. In 2000, 90 percent of the corn Americans ate was bioengineered, as were more than half the soybeans, according to the U.S. Department of Agriculture. Both numbers have increased since then.

  The acronym GMO (genetically modified organism) is used as a blanket term for nearly all forms of food biotech, though it is technically less than accurate since genetic modification is also the basis of conventional breeding methods. Nevertheless, the term has stuck, and I will use it here instead of proposed but less familiar substitutes like transgenics, GM foods, or GM crops. Creating a GMO is a complex process. But the basics can be explained fairly simply: Genes from one organism that carry specific traits—resistance to a disease, increased size, or more rapid maturation—are added to the genetic material of another. The organisms can be vastly different, such as DNA from a bacterium added to tomatoes, or relatively similar, like crossing radishes with bananas (such a mixture is currently being studied for providing resistance to fusarium fungus).

  The techniques are precise—microscopic tools make researchers in the field the modern equivalent of Swiss watchmakers—but the basics you learned in high school biology are the same. You’ll recall that chromosomes are sort of a package for DNA; every living thing has a specific number of chromosome pairs—in nature, for the most part, one from each parent. Human-influenced crops can be different: A and B sequenced bananas can contain two or three sets of chromosomes. Cavendish contains three.

  The DNA is arranged in the chromosome in wrapped strands. The commonly used analogy is a spool of thread; if a strand of human DNA was pulled straight, it would be about the height of Yao Ming, currently the tallest player in the NBA. If DNA is one of the “building blocks” of life—containing a blueprint for an organism’s specific traits (like the ability to hear or see, or thickness of skin)—then the genes it is made up of are the workers that execute the blueprint by creating specific proteins that assemble to form the structure that supports the trait, whether on an individual level, to make hemoglobin, the protein that allows blood to carry oxygen through the body, or in concert, as multiple proteins gather to form an eye or an elephant or a banana plant. Sometimes genes mutate. A hemoglobin mutation causes sickle cell trait, and it was probably a mutation that initially yielded a seedless banana thousands of years ago.

  Understanding genetic modification requires shifting the metaphor. Instead of a spool of thread, imagine that chromosomes are an old-fashioned film reel—the kind that used to jam up the projectors in that same biology class. The film wrapped around the reel is made up of individual frames. If the frames are genes, then creating a GMO involves splicing the genes from one movie, perhaps Gone with the Wind, into another—let’s say Star Wars. The result is something that should contain the best qualities of both: Rhett Butler played by Harrison Ford and Scarlet O’Hara with a cinnamon-bun hairstyle.

  If you’re using handy, expensive lab toys, the cut-and-paste job isn’t all that difficult. The hard part is determining which gene performs what function. That was the purpose of the human genome project—launched in 1990 and completed in 2003—that mapped the approximately 25,000 genes contained within the human body (the function of each and every gene is far from known, but having the map has allowed thousands of scientists around the world to begin individual and highly specialized efforts to determine and take advantage of that information).

  Mapping of the banana genome was begun in 2001 by a consortium of twenty-seven publicly funded organizations in thirteen countries. The goal was to have the entire banana genetic sequence—using a wild Asian banana as the base material—decoded within five to ten years. The banana is only the third major crop to undergo gene sequencing. The first was rice—though rice lags behind wheat and corn in global consumption, there are more people absolutely dependent on it, as with the banana in Africa—completed in 2005. (Rice contains about 37,000 genes. The 25,000 found in Homo sapiens is double that in a fruit fly and about the same as in the Japanese fugu puffer fish; the seaborne creature’s genes contain the recipe for a deadly toxin, which kills several hundred Japanese diners a year as they eat the fish, which has to be precisely sliced in order to avoid the poison in its liver and skin.)

  The first concrete results of the banana genome project came in 2005, when researchers announced they’d mapped more than half of the banana’s genes (the project is on track to be completed by the end of 2008). About five thousand of those genes were decoded by Brazilian scientists, who said they’d found twenty that could potentially be used to bestow disease resistance on cultivated bananas. That may sound like a small number, but that total has already made the process forty thousand times more efficient than the million-toone success rate yielded by the manual search for seeds required in traditional breeding.

  IN THE DOCTOR’S OFFICE–LIKE BASEMENT of the Leuven lab, I am looking directly at some of those genes—though without a microscope, they look like little more than a flask of water. Serge Remy, one of the Leuven researchers, is taking me on a step-by-step walk-through of the banana-manipulation process. The flask contains thousands of banana cells, derived from one of the 1,200 varieties cryogenically preserved at the Belgian facility; each cell can mature into a plant, using a process similar to the one that yields banana embryos at FHIA. But rather than simply growing these cells into baby bananas, Remy is using them as base material for what geneticists term transformation.

  Though cut-and-paste is a good metaphor for the process, the actual procedure isn’t done with an X-Acto knife and glue. Most modern transformation of plants, including bananas, is accomplished two ways. The first technique involves brute force: In a process called “particle bombardment,” tiny pieces of gold or tungsten are coated with DNA and blasted at high velocity into living plant cells or embryos. The shooting can be done with miniature air guns, mechanical devices (think of toy cannons), or via magnetic or electrical discharge. The most subtle and ingenious way to carry transforming material into a test organism is by using bacteria. Remy holds up the flask and taps on it, as if I could see what he’s about to explain: “We use bacteria that are naturally found in soil,” he says. The bacteria carries the material with the desired trait into the host’s DNA. The bacteria attaches itself to the cells and will (if it works; success isn’t guaranteed) ultimately turn up—the formal term is express—in the growing plants. “It really is pretty neat,” Remy adds, pointing at the flask again. All I see is water, but I nod my head in agreement.

  The part that I thought was coolest came next. The biggest problem with a conventional hybrid banana, as I learned both from Swennen and during my visit to Honduras, is time. With a conventional hybrid, you’ve got to wait weeks or even years for a growing plant to emerge. Even then, you’ll need several generations to determine if the qualities you’ve tried to breed into the new banana actually exist. With genetic transformation, that information can be obtained in just days or hours. The trick is to c
reate flags, or markers, that indicate whether a change has occurred. These markers are supplementary genes that impart an additional, easy-to-see quality to the transformed organism. A common marker gene is one that confers resistance to antibiotics. Scientists insert the marker, and then dose the transformed organism with the antibiotic. Only the ones that have picked up resistance will survive; the marker gene acts as an indicator that the real-deal genes have actually come along for the ride. Other marker genes are called “reporter” genes. They provide a visual cue that the transformation has taken place. Some reporters genes actually emit light—like a firefly—when activated. You can see them glowing in the dark.

  REMY AND I MOVE AWAY FROM THE TEST TUBES, toward a container filled with petri dishes. These microbananas are a week old, and many are turning black, succumbing to the bacteria. They’ll soon be discarded. For the next four months, the winnowing process will continue; after six months, the cells will have become plantlets and are transferred to test tubes.

  After a year in vitro, the infant bananas head out to the field. At this point, the process becomes more traditional. Genetic transformation of bananas is efficient in the early stages because you can produce thousands of transformed organisms very quickly. Once the plants start to look like plants, the growth pattern is the same as with any other banana. “You need to see the plant go through several cycles, probably five years,” Remy says, “in order to find out if what you’ve been trying to obtain is actually there and functional.”

  A test-tube banana, at the Belgian

  banana genetics lab.

  Or that’s the way it should work. I ask Remy if there’s any place I can go to see those test-tube fruits actually growing on a plantation. He frowns. He’s bombarded and vectored tens of thousands of genes into a never-ending parade of test tubes and petri dishes. “I’m talking about the ideal timeline,” he says. “But that’s not the way it works at the moment.”

  I ask him why. His frown deepens. “It has nothing to do with science,” he says.

  CHAPTER 34

  Frankenbanana

  THE WORD PHIL ROWE USED to describe the banana’s receptivity to conventional breeding was “intractable.” He meant “stubborn.” When time is short, it would be more accurate to say: impossible. The first epidemic of Panama disease appeared in a less-connected world and took most of a century to run its course—and even then conventional banana-breeding methods crawled along, unable to keep pace. Black Sigatoka spread across Africa in less than a decade, reducing crop efficiency by more than two-thirds by the 1980s. Panama disease has been on the move for about twenty years now. That malady’s boundaries—China to the east, India to the west, and all the way through Australia to the south—cover a much larger range than Africa’s. Its speed is especially disconcerting given the bodies of water separating the afflicted areas.

  Since the traditional method of creating hybrids—hand pollinating, hunting for seeds in thousands of bananas, and then searching for the right qualities in millions of fruit—takes so long, today’s banana producers must rely on external techniques to build resistance to ailments. That means practices that look much like those used in the past by United Fruit and the rest of the early banana industry: New plantations in virgin forest; applications of chemicals; environmental damage—the cycle that began a century ago continues. When an airborne blight strikes, the malady must be fought with expensive applications of chemicals, dumped from the sky.

  The banana has changed the world, but for all practical purposes, it can’t change itself, and it has so far not cooperated with human efforts to make it turn a new leaf. The techniques being developed by the scientists in Leuven and at similar labs around the world—in Australia, Canada, Brazil, India, and a dozen other countries—may be the banana’s only hope.

  But something strange happens when the mechanics of banana biotechnology are explained. Scientists like Swennen and Remy see it all the time. So did I as I was researching this book.

  People become uncomfortable. Even scared. When they learn about modifying a Polynesian banana to contain extra quantities of vitamin A, they seem to approve. When they learn that the marker genes come from fishes (it’s true), they’re horrified. It doesn’t matter that none of this foreign genetic material would actually get into a growing banana plant (no more than a socket wrench would get into your car’s oil supply after you’ve visited a Jiffy Lube). People cringe. They don’t like the idea of marine life, or any member of the animal kingdom, having anything to do with a banana. “Don’t mix anything that has eyes with my fruit,” one friend told me when I described the process to her.

  Even straightforward banana-improvement projects—only affecting taste or ripening or the ability to fight in-the-field maladies—unnerve a large number of consumers. Crosses with radishes and, of all things, azaleas may help bananas resist Panama disease, since varieties of both of the added plants fight fungus fairly well. Other lab-bred bananas have successfully overcome Sigatoka or gained more controllable ripening and nearly bruise-proof flesh.

  Yet, the truth is that it is unnatural to mix fish with fruit, no matter how harmless; the idea of a vegetable meeting a banana is less discomforting, but it still feels like something beyond the normal.

  “Genetic transformation,” Rony Swennen says, “is revolution, not evolution.”

  For Swennen and his colleagues, that’s a good thing. But for groups against the genetic modification of food—including well-known environmental organizations like Greenpeace and Friends of the Earth—the idea of speeding up, or even replacing, natural processes that have evolved over thousands of years seems like a very bad idea. Lab-made products are often referred to in the media, and by these groups, as “Frankenfoods.” Those using the term typically accompany it with a curdling litany of what sound like edible monstrosities: “Potatoes with bacteria genes, ‘super’ pigs with human growth genes, fish with cattle growth genes, tomatoes with flounder genes, and thousands of other plants, animals and insects,” according to a report from the Center for Food Safety, a Washington DC–based advocacy group. The risks of those products, the group argues, extend to “humans, domesticated animals, wildlife and the environment. Human health effects can include higher risks of toxicity, allergenicity, antibiotic resistance, immune-suppression and cancer. As for environmental impacts, the use of genetic engineering in agriculture will lead to uncontrolled biological pollution, threatening numerous microbial, plant and animal species with extinction, and the potential contamination of all non–genetically engineered life forms with novel and possibly hazardous genetic material.”

  That’s scary. But it is also overblown, according to James K. M. Brown of Britain’s John Innes Centre, an independent research center specializing in plant science and microbiology. “There is no good evidence that, in itself, GM technology harms the safety of food,” Brown says. Some of the issues cited by anti-GM forces are clearly bogus: The use of bacteria, for example, is not inherently dangerous—bacteria are found everywhere; they’re a natural and desired part of yogurt, for example, and adding them to products ranging from soft drinks to candy bars is currently a trendy way to get consumers to spend more money in the supermarket (those products are usually described as “probiotic”). The claim that more people might be allergic to genetically modified foods comes from a study of soybeans crossed with Brazil nuts. The resulting soybeans did exhibit signs of allergenicity, but that wasn’t a surprise, since many people already have an allergic reaction to Brazil nuts (in fact, says Brown, this is a good result, because it “implies that other proteins…such as oral vaccines, should also retain their useful properties when expressed in different plants”).

  The current distribution—and regulation—of biotech crops around the world is mixed. The United States is the world’s most GMO-loaded country. The 123 million acres of transformed crops we grow each year is more than the quantity produced by every other country on earth combined. We also eat more biotech food than anywhe
re else. Some estimates claim that more than half of the processed foods we consume contain GMO ingredients. One of the reasons our food supply is so laden with such products is that development of them is encouraged by the government, and food labels here, unlike in most of the industrialized world, aren’t required to reveal whether, or what, GMO ingredients the product contains (food manufacturers are, however, required to disclose whether or not allergens are contained in their products, which is why you see peanut warnings on everything from loaves of bread to ice cream).

  In Europe the situation is reversed. Though limited development of biotech crops is allowed—researchers have to follow a rigorous permitting and monitoring process—the sale of such foods is almost completely banned. If a GM product is sold, it has to be labeled as such, which tends to make shoppers run away. That bodes poorly for engineered bananas. In 2000, Fyffes—the former United Fruit subsidiary that is one of Europe’s biggest banana importers—surveyed British shoppers, asking if they’d be willing to purchase GM bananas: 82 percent of the respondents said they absolutely wouldn’t. Del Monte has said it will never market transformed bananas; Chiquita and Dole have been less committal, but so far they’ve pledged that nothing on the market is currently modified. It is unlikely that a major banana company would undertake production of a GM fruit if most of the world’s consumers would refuse, or even be unable, to accept them (yet another criteria added to the long list of things that don’t make a commercial banana viable).