|Volume No. 1 Issue No. 38 - Sunday March 02, 2003
| Bye Bye Bananas |
by Fred Pearce of the Boston Globe
Just five scientists stand between the banana and its commercial extinction, researchers are warning. Unless their numbers are dramatically increased, the fate of the world's most popular fruit could be sealed through worldwide indifference.
Headline writers loved it last month when the phallic fruit was exposed as sterile, genetically decrepit, and doomed. The banana's problem is that it is the seedless, infertile mutant cousin of a wild herb. The absence of seeds makes its fruit edible, but also genetically vulnerable, according to researchers from the International Network for the Improvement of Bananas and Plantains in Montpellier, France.
Bananas cannot reproduce sexually. They have survived only because for some 10,000 years banana-lovers have propagated the fruit by taking shoots from the base of the plants. Each cutting is thus a genetic clone. Without the variety generated by sexual reproduction, the world's 500 or so banana varieties are genetically almost identical - and highly prone to new super-pests at large on the world's banana plantations.
According to Emile Frison, the Belgian director of the network, unless there are some scientific breakthroughs soon, ''we can be fairly confident of a drastic decline in banana production worldwide, and possibly the complete collapse of the banana as a major staple as well as an export crop.''
The most widespread banana disease currently is a leaf fungus called black Sigatoka. It cuts yields by 50 percent or more on hundreds of millions of small farms across the tropics. Commercial banana plantations keep up production with weekly applications of fungicides - the most intensive application of chemicals on any major food crop. But now a new strain of an old disease, Panama disease, threatens to make even fungicides useless.
Forty years ago, Panama disease, a soil fungus that attacks banana roots, wiped out the world's then-favorite banana variety, the Gros Michel. Plantation owners switched to a backup variety resistant to the disease, the Cavendish. But the Cavendish has no resistance to a new Panama strain that is spreading round the world.
''Fungicides won't work against Panama disease because it is so persistent in the soil,'' Frison said. ''New resistant banana varieties are urgently needed.'' But, coming up with new hybrids of the sexless fruit is an extremely time-consuming business. To cross one variety with another requires laboriously grafting cuttings and waiting 18 months for the fruit to appear.
Probably for that reason, Frison said, little research has been done. Almost the only result of 80 years of endeavor has been a banana that tastes like an apple and is only eaten in Cuba, where there is nothing else on the supermarket shelves.
Now, just at a moment of greatest crisis for the banana, tragedy has struck the tiny scientific community of banana experts. Three years ago, three banana researchers working for the International Institute for Tropical Agriculture in Uganda died when their plane crashed into the sea off West Africa. And soon after, the man widely regarded as the world's top banana breeder, Phil Rowe, died in Honduras.
''Only five scientists worldwide are presently working to breed improved bananas,'' Frison told the Globe. He blamed a lack of interest from the big banana companies, who acknowledge that they got bored with funding unsuccessful breeding programs and now concentrate their research budgets on finding new fungicides.
David McLaughlin, Chiquita's senior director for environmental affairs, said the company had supported breeding for a better, more disease-resistant banana for 40 years. ''It cost us a lot of money for very little result,'' he said. ''We concentrate on research into fungicides now.'' And he defended the company's reluctance to become involved with biotechnology. ''It's expensive and there are serious questions about consumer acceptance.''
The crisis is a matter of life and death. Nearly 90 percent of the bananas eaten around the world are grown for local consumption in backyards and on small plots in developing countries. The banana ranks fourth after rice, wheat, and maize among the world's most important food crops. Carbohydrate-rich varieties known as plantains or cooking bananas are an essential staple for hundreds of millions of people.
Frison said that parts of Africa face an equivalent of the Irish potato famine as their bananas succumb to Panama disease, black Sigatoka, weevils, nematodes and a virus that worms its way into the banana's genes, infecting each new cloned sucker.
The banana was first propagated by Stone Age plant breeders somewhere in Southeast Asia. Perhaps 10,000 years ago, they stumbled on a seedless - and, hence, edible - fruit from a mutant form of a wild jungle herb called Musa acuminata. They began to take cuttings. The new fruit proved popular.
The first banana boats may have been ancient vessels crossing the Indian Ocean to Africa. Two years ago, researchers rooting around in a fossilized rubbish pit in Cameroon found mineralized banana tissue 2,500 years old. Pierre de Maret, a cultural anthropologist at the University of Brussels who made the discovery, said he believes the highly productive rainforest crop may have helped the Bantu people to spread across Africa and eventually become the dominant people across much of the continent.
Modern banana varieties became established after European Colonial botanists brought back promising finds from the gardens of Southeast Asia in the early 19th century. The French found the Gros Michel and the British found the Cavendish, named after the family of the Duke of Devonshire who kept the first samples at his ancestral home at Chatsworth.
Transferred to plantations in faraway Latin America, these varieties flourished. But their ancient Asian pests have been tracking them down ever since. The new version of Panama disease, called ''race 4,'' is now killing Cavendish bananas and many other varieties in Australia, South Africa and parts of Asia. ''It is only a matter of time before it reaches the hub of commercial production in Latin America and the Caribbean,'' Frison said.
For most researchers, the big hope is genetic manipulation, which they believe will speed up the search for resistant hybrids. They are currently looking for genes in wild Asian bananas that can resist diseases such as black Sigatoka and Panama disease.
Genetically modified bananas, they argue, should not frighten anti-GM activists. Being sterile, the plant won't be able to pass on its modified genes to nearby plants through sexual reproduction. But one anti-GM campaigner, Gundula Azeez of the UK Soil Association, warned against seeing GM technology as a quick fix for the banana. ''Genetic engineering can only introduce single traits, which mean that it would only resolve the immediate disease problem and will run into the same resistance treadmill that the chemical approach has.''
Not everyone is pessimistic about the banana's future. Normally sterile banana varieties sometimes mutate to produce a few seeds that can be used to induce sexual reproduction. But the logistics are daunting. In one successful experiment using this method, researchers hand-pollinated 30,000 commercial banana plants with pollen from wild bananas.
The resulting fruit - all 400 tons of it - produced just 15 seeds, only a third of which germinated. Even so, David Jones, editor of the journal Diseases of Banana, Abaca and Enset, argued that it may be possible in this way to breed a new version of the Gros Michel banana that can resist Panama disease.
Meanwhile, Philippe Vain of Britain's John Innes agricultural research center last month announced success in producing a version of the East African cooking banana that resists nematodes using GM techniques. It is a small and potentially significant victory.
But, as the tiny band of banana scientists go to work, ''race 4'' is advancing. And, Frison said, ''when it reaches Latin America, it will do to the Cavendish what its predecessor did to Gros Michael.'' That is, wipe it out as a commercial crop.