SCIENCE: New Consortium Launches Banana Genome Project

By Jim Lobe Reprint | | Print |

Jim Lobe

WASHINGTON, Jul 19 2001 (IPS) - International research centres have launched a five-year project to sequence the genome of the wild banana in hopes of learning how to make its domestic varieties, grown on three continents, more resistant to diseases and pests.

The effort, which will be led by the International Network for the Improvement of Banana and Plantain (INIBAP), aims to benefit millions of small farmers who grow bananas or plantains as a staple crop and cannot afford the pesticides and fungicides used by commercial growers to protect their crops.

Organizers of the effort say they want to ensure that any benefits derived from the research are provided to small farmers without their having to pay royalties.

“Our main interest is not the bananas we find in the supermarket here or in Europe,” INIBAP director Emile Frison told IPS. “More than 85 percent of bananas produced in the world are consumed locally and are basically a staple food. We want to introduce resistance in those varieties.”

He added that the effort should cost between four million and five million dollars each year of the project. About half of that will come from institutions already working on banana genomic research, including the governments of Australia, Belgium France, India, Mexico, and the United States.

Additional financing for the project is expected from the European Union and the US National Science Foundation, according to Frison.

Jane Rissler, of the Union of Concerned Scientists, welcomed the “use of genomics to enhance traditional breeding. There should be more financing for this kind of traditional breeding.”

Given the status of bananas and plantains as the Third World’s fourth most important food crop – after rice, wheat and corn – the project’s impact could be quite broad.

An estimated half billion farmers in some 120 countries grow bananas or plantains. Banana or plantain is the major source of dietary carbohydrate, as well as phosphorus, calcium, potassium and vitamins A and C for some 20 million people, mostly in East Africa.

More than 58 million tonnes of bananas and 30 million tonnes of plantains were produced worldwide last year, according to the Food and Agriculture Organisation (FAO) in Rome. India was the largest banana producer at 11 million tonnes, while Uganda, with nine million tonnes, was the world’s largest producer of plantains.

Only about 10 percent of the world’s bananas and plantains are grown for export, and most of that comes from Latin America and the Caribbean, which also produce the world’s highest yields per hectare.

A variety of pests, particularly banana weevil and parasitic nematodes, threaten both bananas and plantains. Similarly, the plant is highly susceptible to a number of deadly diseases, including Black Sigatoka leaf spot disease, fungal leaf spot, Fusarium wilt, and banana streak virus, among others.

Fusarium, also called Panama disease, wiped out what was then the main export banana, Gros Michel, more than 50 years ago.

Cavendish replaced Gros Michel in the 1940s after proving resistant to Fusarium but now is threatened by a new disease, Tropical Race 4, which has already devastated the crop in Malaysia.

Black Sigatoka is perhaps the most pervasive threat to banana and plantain crops. Originally from Fiji, “it now covers the entire world, causing production losses of between 30 and 50 percent” in the fields it infects, according to Frison. This hits smallholders hardest, because they cannot afford the fungicides needed to combat the disease.

“When Black Sigatoka strikes, farmers can do little more than watch their plants die. Increased hunger can swiftly follow,” he said.

The reason domesticated bananas and plantains are so susceptible to pests and disease resides in the fact that they are sterile and reproduce themselves by sprouting new branches from their stem. Much like clones, those new branches may be transplanted, but their genealogical make-up is identical to the plant that sprouted them.

While the domesticated varieties have been at an evolutionary standstill, their wild cousins, which are found in Southeast Asia, still reproduce through seeds and thus by necessity have overcome the challenges, including the same pests and diseases which have afflicted domestic crops, that evolution has produced.

“We know from observing the wild species that there are sources of resistance to these pests and diseases,” said Frison, “A coordinated effort by scientists worldwide is needed to unlock the diversity found in these bananas.”

The ‘Global Musa (Banana) Genomics Consortium’ is the name of that effort. It includes the International Institute for Tropical Agriculture in Nigeria, the US-based Institute for Genomic Research, research institutes from Australia, Belgium, Brazil, the Czech Republic, France, Guadeloupe, Germany, India, Mexico and Britain, and INIBAP, which is a programme of the International Plant Genetic Resources Institute in Rome.

Scientists have thus far sequenced the genome of only two plants: rice and arabidopsis, a mustard strain. Comprised of only 11 chromosomes with a total of between 500 million and 600 million base pairs, the banana genome is among the smallest of all plants, and thus can be sequenced more quickly.

Frison said some commercial companies have already begun some work on banana genomics and may therefore seek to exchange information with the consortium.

“By building a strong public and non-profit consortium that unites experts in genomics and plant biology, we hope to be able to approach the private sector later from a position of strength,” he said. “We want to guarantee that any results, such as disease-resistant banana strains, will be made available to small-holder farmers on a royalty-free basis, even if they have commercial applications.”

If the consortium succeeds in discovering those resistances, the environmental impact could be very positive. Commercial growers rely heavily on chemical fungicides, spraying their crops as often as 50 times a year – about ten times the average for intensive agriculture in industrialised countries.

“If we can devise resistant banana varieties, we could possibly do away with fungicides and pesticides altogether,” said Frison.