BBC Thursday, 19 July, 2001, 06:10 GMT 07:10 UK Banana targeted by code crackers

Bananas have become a hugely important world food crop The banana will be the next major food crop to have its entire collection of genes decoded, an international consortium of scientists has announced.

The banana genome should allow researchers to develop strains that are more resistant to disease and which require fewer agrochemicals to be applied during their cultivation.

Researchers also have high hopes for the banana as a so-called nutraceutical - its natural packaging could make it an ideal way to transport and consume drugs.

Scientists from 11 countries will make up the newly founded Global Musa (Banana) Genomics Consortium.

Following rice and the small weed Arabidopsis thaliana, the banana will become only the third plant to be sequenced.

Food calories

The banana's genome is relatively small. The genetic code is just 500 to 600 million "letters", or base pairs, in length. And this DNA is wound on to 11 chromosomes.

Farmers in 120 countries grow an estimated 95 million tonnes of bananas annually, with 85% of the global crop produced for home consumption and local trade.

Bananas and their longer, greener cousin, the plantain, represent the developing world's fourth most important food crop, providing more than one-quarter of all food calories to residents in many parts of Africa.

"Banana will be the first exclusively tropical crop to be sequenced," said Dr Emile Frison, one of the lead researchers and director of the International Network for the Improvement of Banana and Plantain in Montpelier, France.

Its economic importance makes the banana an ideal candidate for sequencing - but so too does its increasing vulnerability to disease. New strains are now needed to resist the fungus Black Sigatoka, which afflicts the starchy, potato-like bananas traditionally consumed in the developing world. The fungus, which attacks banana leaves and can reduce yields by up to 50%, is extremely costly to control with chemical spraying.

Seedless and sterile

Large-scale use of agrochemicals is also needed to produce the sweet, Cavendish dessert bananas favoured by US and European consumers.

"Ancient farmers selected banana strains that were seedless and thus sterile, and grew the fruit through vegetative sprouting," Dr Frison said.

"Cultivated bananas have, therefore, been at a near evolutionary standstill for thousands of years and lack the genetic diversity needed to fight off disease."

Scientists hope also to acquire much general information that will help them understand how plants grow.

"If we've learned anything from genomics, it is how little we know about biology," said Dr Claire Fraser, president of The Institute for Genomic Research (Tigr) in Rockville, Maryland, US.

"We expect that the banana genome sequencing will reveal surprising insights into the evolution of plants."

-- Anonymous, July 19, 2001