Scientists race to create a hybrid to take the place of the dwindling Cavendish banana.
Mon, Apr 13, 2009 at 11:39 AM
Back in 2003, the magazine New Scientist ran a cover story declaring that the banana was on the brink of extinction. The problem, the article explained, was that commercial bananas were genetically bankrupt: sterile, seedless clones with no genetic diversity and no resistance to a new wave of virulent fungal diseases. “The banana business has reached crisis point,” the magazine gravely pronounced. “The world’s favorite fruit could disappear forever in 10 years’ time.”
The prediction sparked a media storm, with newspapers around the world warning their readers that the humble banana was heading for oblivion. Five years on, though, bananas are still being sliced into breakfast cereal across the country: Upwards of 100 million metric tons of bananas are being produced each year, feeding a $5 billion export market. The curved yellow fruit remains the fourth most important food crop in the world, and a dietary staple of some 600 million people across Latin American and sub-Saharan Africa. So has the world’s favorite fruit pulled back from the brink―or are we still en route for bananageddon?
In fact, scientists say, the outlook is still pretty bleak for the banana. Commercial growers remain wedded to a single variety known as the Cavendish, the bright yellow fruit found on US supermarket shelves; meanwhile, a lethal and fungicide-resistant infection called Panama Disease has decimated plantations across Southeast Asia and is widely expected to spread into plantations in Latin America and Africa. “It’s not a matter of if, it’s a matter of when,” says Randy Ploetz, a plant pathologist at the University of Florida. “These are serious problems that haven’t changed since the New Scientist article.”
Lest we underestimate the risk of a Cavendish catastrophe, it’s worth remembering that today’s top banana was itself introduced as a replacement for the bigger and tastier Gros Michel banana, which was all but wiped out by Panama Disease in the 1950s. By 1960, outbreaks had destroyed stock worth $400 million, equivalent to more than $2.9 billion at today’s prices; only the speedy introduction of the more resistant Cavendish saved banana giants like Chiquita and Dole from bankruptcy. Now, researchers say, a new strain of Panama Disease has adapted to target Cavendish bananas―and this time, there’s no replacement waiting in the wings.
That’s driven scientists at the non-profit Honduran Agricultural Research Foundation to try to create an understudy for the Cavendish by cross-breeding the plant with “heirloom” species gathered from around the world. But creating hybrids from sterile, slow-growing plants is a thankless task: each year researchers painstakingly cross-pollenate thousands of banana plants, then peel and examine millions of bananas in the hope of finding one or two seeds. Even then, there’s no telling whether the seed will germinate, let alone produce a palatable or disease-resistant fruit. “It takes about four years, if everything works,” says Adolfo Martinez, the foundation’s director. “The chances of success are very small.”
To make matters worse, the dominance of the Cavendish banana is leading to the erosion of banana diversity in the wild and on subsistence farms in India and Africa. “We’re losing those [wild] bananas, and with them the chance to strengthen the Cavendish,” says banana historian Dan Koeppel, author of Banana: The Fate of the Fruit That Changed the World.
That’s led researchers at Belgium’s Catholic University of Leuven to begin cryogenically preserving bananas from around the world, in a last-ditch attempt to preserve their genetic patterns. The Leuven team is also working to sequence the banana’s genome, with a view to isolating the genes that regulate disease resistance; it’s still early days, but the group has already begun field trials of a Gros Michel banana patched with resistance-boosting genes from rice plants. “I don’t believe we’ll lose the banana in five years,” says Rony Swennen, director of Leuven’s Laboratory for Tropical Crop Improvement. “But it’ll happen in our lifetime, even if we can’t say exactly when. It’s our duty as scientists to try to be ready."
Story by Ben Whitford. This article originally appeared in "Plenty" in May 2008.