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Building A Better Banana

It is the world's No. 1 fruit, with millions of people dependent on it to stay alive. Now diseases threaten many varieties, prompting a search for new hybrids of the "smile of nature"

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Tataw is studying the link between plantain varieties and local culinary practices. “Traditionally, each local variety is used in a very particular way,” she says while we’re stopped at a small farm. “For example, these bigger plantains, known as horn type, are used for roasting when picked at a certain stage of ripeness. When picked at a slightly different stage, they are dried, crushed into a paste and served with dried fish.”

One CARBAP mission is to introduce disease-resistant varieties that farmers can test in their own fields, side by side with the local plantains they are accustomed to growing. We stop beside a remote country road on MountCameroon’s east slope. Tataw, Tomekpé, two local farmers (both women), a government agriculture official and I walk single file along a narrow, pumice-covered path. To me—a Midwestern American reared on the sight of neat corn and soybean rows stretching to the horizon—we appear to be bushwhacking through a patch of wild jungle upon which Mount Cameroon regularly rains down boulders the size of Sputnik. It is not jungle, however, but laboriously cultivated farmland, carefully tended plots of mixed cocoa trees, oil palms, plantains, corn and papaya, with occasional patches of ground-hugging cocoyams or spindly cassava shrubs.

We step across an invisible boundary where those crops give way to bananas. A small farmers’ cooperative has planted 25 different varieties using pest-free suckers provided by CARBAP. A few are disease-resistant hybrids developed at the Honduran Foundation for Agricultural Research (FHIA), the most prolific of the world’s half-dozen banana-breeding programs. FHIA hybrids, touted in the international press as potential saviors, shrug off the effects of black sigatoka and other serious Musa scourges. In this field, farmers are experimenting with two of the hybrids, FHIA-02 and FHIA-25. Both can be cooked when green and, unlike plantains, which remain starchy when ripe, can also be eaten out-of-hand as dessert bananas.

Someone offers me a bright yellow FHIA-02 banana. It’s medium-sized, firm and buttery in the mouth and moderately sweet with a slightly acidic, tangy edge. It seems like a fine banana to me, but it is not getting rave reviews from the farmers here. They prefer larger, starchier, more typical plantain types. Of the 25 CARBAP introductions, the favorite is a dry-textured, orange plantain from Papua New Guinea called Maritu, which commands a premium at local markets. FHIA-02 often winds up as animal feed despite its disease-resistance.

Breeding an überbanana that fends off lethal diseases while also meeting the exacting requirements of growers and consumers isn’t rocket science. It’s harder than that. How do you arrange matings between plants that, for the most part, can’t mate? The trick is to make ingenious use of whatever traces of fertility—pollen-bearing male flower parts and seed-bearing fruits—you can find among varieties, wild or cultivated, that have the traits you are looking for. To improve your chances of success, you need access to the largest possible pool of genetic diversity, such as the germ plasm preserved in Belgium and in CARBAP’s extensive field collection. Tomekpé and his associates found a promising pollinator in a wild banana from India called Calcutta 4. “It makes a good male parent,” Tomekpé explains, “because it is highly resistant to black sigatoka and nematodes, it’s highly male-fertile, and it’s a dwarf.” Dwarfism is a useful trait for CARBAP’s geneticists, because their main goal for years has been to develop disease-resistant plantain hybrids that have large bunches but short stature. Reduced height not only makes the plants easier for farmers to work with but also less prone to toppling by wind, a major cause of banana crop loss everywhere.

Phil Rowe, who led the FHIA breeding program for many years before his death in 2003, invented the now-standard procedure for creating banana hybrids. The first step is to gather as much pollen as possible from the chosen male parent and use it to fertilize potential female parents at the flowering stage. Next comes a four- or five-month wait for the plants to produce fruit. Then the bananas are harvested, peeled by hand and pressed through a sieve. A ton of fruit might yield a handful of seeds, less than half of which will germinate naturally. After the precious few seedlings are planted comes another 9- to 18-month wait. Finally, up to two years after the initial mating, disease resistance and other characteristics can be evaluated.

Rowe and his colleagues repeated this painstaking procedure for tens of thousands of different parental crosses. The vast majority yielded offspring that didn’t pass muster. Only after decades of this work did Rowe’s lab release its first potentially commercial hybrid, FHIA-01, a.k.a. Goldfinger. It is the world’s first disease-resistant sweet banana with the potential to take on the almighty Cavendish.

The process is not quite as slow today, thanks to molecular genetics techniques. “We can also use molecular techniques to perform rapid screening of hybrids for susceptibility to diseases, as well as for nutritional and other characteristics, such as fruit texture and taste,” says Pascal Noupadja, the leader of CARBAP’s breeding lab. “We use molecular techniques for screening and propagation. But we are working only with conventional breeding here, with pollen and flowers—no gene splicing. We leave genetic modification of bananas up to other labs.”

“Our program is only ten years old,” Tomekpé chimes in. “But we have created several hundred plantains of a new type—dwarf-size plants with high resistance to disease and pests, plus good productivity and fruit character.” At the request of the European Union (EU), which provides most of CARBAP’s funding, Tomekpé recently broadened his breeding program to include dessert bananas. “The EU said they’d continue to support us but asked that we work on preserving the dessert banana too. That’s what Europeans know and see. They don’t want to see their bananas disappear.” Dessert bananas, which are less genetically diverse and even less fertile than plantains, are harder to breed. The Cavendish is not a candidate for conventional breeding at all, as it produces absolutely no pollen or seeds. It’s an evolutionary dead end. Because of its high susceptibility to many diseases and its inability to acquire resistance through breeding (although some scientists think gene splicing could change that, someday), scientists worry that a particularly nasty pest that spread widely could wipe it out.

The banana industry has experienced just such a doomsday scenario once before. International trade in the fruit began in the early 1870s, when Lorenzo Dow Baker, a Cape Cod fishing captain, brought the first large banana shipments to the United States. The variety that Baker carried from Jamaica to New England on his schooner was called Gros Michel. “Big Mike” reigned as the No. 1 export banana until the 1940s and ’50s, when a fierce soil pathogen known as Panama disease devastated it. Yet Panama disease left Cavendish-type bananas unscathed. The Cavendish didn’t taste as good as the Gros Michel, and its thinner skin made the fingers more difficult to handle and ship without bruising. But the major banana export concerns, led by the huge United Fruit Company (which Baker co-founded as the Boston Fruit Company in 1884), had no choice but to replant their vast plantations with Cavendish and to overhaul the system of banana mass production that United Fruit (now Chiquita Brands International) had invented around the turn of the 20th century. In the original system, Gros Michels remained intact in enormous bunches from the farm to the grocery store. But with the fragile Cavendish, plantation owners had to build packing houses on each farm, so the big bunches could be cut down to small clusters, washed, and gently laid into protective boxes before shipping. The costly transition to a new banana took more than a decade.


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