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Behold the atheist’s worst nightmare. But what about coconuts?

Some banana facts which that Ned Flanders guy might not know:

The banana plant is not a tree, but actually classed as a giant herb, because it does not have a woody stem.

Wild bananas, native to the jungles of south-east asia, have less pulp than cultivated varieties and are full of large seeds. Between 7000 and 10,000 years ago, rare triploid mutants were discovered and cultivated by hunter-gatherers.

In normal diploid species the sex cells get one of the two copies that are present of each chromosome. A triploid plant has three of each chromosome instead of the normal two, and so seldom produce eggs or sperm with balanced numbers. This makes the bananas sterile and lacking in seeds. The odd one occurs very occasionally, but the dark coloured bits down the centre of the fleshy part of the fruit are all that normally is evident of the vestigial seeds. After bearing fruit the banana plant produces side-shoots at the base of the stalk, called suckers, which must be removed and planted to propagate the variety.

Because the bananas we eat cannot have sex (umm, not with each other anyway - stop sniggering at the back), there is little genetic diversity within a variety. Being unable use sexual reproduction as a way of shuffling the genetic deck makes bananas extremely vulnerable to disease. The Gros Michel variety was the major exported variety of banana until about 1950. It is no longer grown commercially due to susceptability to Panama disease, which is caused by a soil fungus. Today it has been replaced by the Cavendish, which many say is neither as sweet nor as rich as the Gros Michel.

The banana is in serious danger. The Cavendish, and most other varieties, some used as staple crops in much of Africa, are vulnerable to another fungal disease called black Sigatoka. Fungicides are relied on more and more, and are having a decreasing effect against the disease. Panama disease has also reappeared in a new and virulent form which attacks the Cavendish. Because the disease is spread by a soil fungus, rather than attacking the leaves like black Sigatoka, fungicides cannot control it. The Cavendish has been wiped out in several Asian countries, but the disease has not yet spread to the Americas. What if it does? Yes, in the future we may have no bananas.

Banana breeders are in a race against time. And banana breeding is not fun. You have to hand-pollinate hectares of banana plantation, and then seive through hundreds of tonnes of banana just to find single digit numbers of seeds. A new resistant hybrid has been developed, but neither western supermarkets nor peasant farmers like it much. It is said to taste more like an apple than a banana. Only Cuba, which cannot afford expensive fungicides, grows it on a large scale.

The other option is genetic engineering. A project to sequence the genome of a wild banana species was announced in 2001, and the first phase completed last year. Many of the wild, sexually reproducing banana species are resistant to the fungal diseases and 20 genes have been identified which may help in creating new resistant species of seedless banana. But the UN Food and Agriculture Organisation has recently warned that many Indian species of wild banana are becoming extinct due to loss of habitat, and with them we might be losing genes that could save the edible varieties.

So to summerise, perhaps the banana is an atheists nightmare. It will greatly please our Ned Flanders to learn the bananas he admires so much have probably not evolved much for thousands of years, because they do not get involved in all that sinful sexual reproduction malarky. Unfortunately the funguses do evolve, and the vast monocultures planted world-wide have been devastated by the diseases they cause. If we want to continue to eat bananas, we may have to play God ourselves, and intelligently design a new GM variety.

This entry was posted on Friday, May 12th, 2006 at 03:31 and is filed under General. You can follow any responses to this entry through the RSS 2.0 feed. You can leave a response, or trackback from your own site.