[Press and Public Relations] Global Consortium Announces Plans to Sequence Banana Genome

August 2001

No. 107

University of Leicester Professor in pioneering project

Scientists from 11 countries - including the University of Leicester in the UK - announced the founding of an international consortium to sequence the banana genome within five years. The scientists from governmental, university, and nonprofit organizations will use the new genetic data to enable developing-world farmers to grow bananas that are able to resist the fungus Black Sigatoka, as well as other diseases and pests. Bananas are a staple food for nearly half a billion people worldwide, but their crops are increasingly lost to disease. The genome sequence will also benefit US and European consumers of the popular dessert banana, one of the world's most chemically dependent crops.

"Ancient farmers selected banana strains that were seedless and thus sterile, and grew the fruit through vegetative sprouting," said Emile Frison, PhD, Director of the Montpellier, France-based International Network for the Improvement of Banana and Plantain. "Cultivated bananas have, therefore, been at a near evolutionary standstill for thousands of years and lack the genetic diversity needed to fight off disease. A coordinated effort by scientists worldwide is needed to unlock the diversity found in bananas that still grow and reproduce in the wild."

The project involves Professor Pat Heslop-Harrison of the Department of Biology at the University of Leicester. Professor Heslop-Harrison and his group study the biology of the cell nucleus.

The International Network for the Improvement of Banana and Plantain (INIBAP), a program of the Rome-based International Plant Genetic Resources Institute (IPGRI), is leading the effort, which brings together organizations from Australia, Belgium, Brazil, the Czech Republic, France, Germany, India, Mexico, the United Kingdom, and the United States. The newly-founded Global Musa (Banana) Genomics Consortium includes the International Institute for Tropical Agriculture (IITA) based in Nigeria. IPGRI and IITA are Future Harvest Centers. The Consortium also includes the Institute for Genomic Research (TIGR), which previously collaborated in sequencing the genomes of rice and Arabidopsis (a plant in the mustard family), as well as sequencing the parasite that causes East Coast fever - a leading cause of death in African cattle. Scientists will map the banana genome using asexually-reproducing wild species of banana from Southeast Asia.

"Banana will be the first exclusively tropical crop to be sequenced," said Frison. "More than a popular snack, bananas are a staple food that many African families eat for every meal. This is our chance to develop a crop that won't fail for them and that may help lift them out of hunger and poverty."

Cutting Back on Agricultural Chemicals

Farmers in 120 countries grow bananas and plantains. Plantains are long, green bananas - one of six major groups of cooking bananas, found mostly in West Africa and Latin America. Of the 95 million metric tons of bananas grown annually, approximately one-third is produced in each of Latin America, Africa, and Asia. Some 85 per cent of the global crop is produced for home consumption and local trade, largely without the use of pesticides, leaving them highly susceptible to disease. The 15 per cent of the global banana crop grown for export relies heavily on chemical inputs.

Bananas and plantains together are the developing world's fourth most important food crop, following rice, wheat, and corn. In parts of Africa, bananas provide more than one-quarter of all food calories. When ripe, most banana types are not sweet like the imported dessert Cavendish bananas eaten in Europe and North America, but starchy like a potato and eaten cooked. Banana varieties, all grouped under the scientific name of Musa, are rich in vitamins A, C, and B6 and contain high levels of calcium, potassium, and phosphorus, providing an essential source of nutrition in developing countries.

Bananas are threatened by the rapidly spreading fungus Black Sigatoka that has been undermining banana production for the past three decades. It has reached almost every banana-growing region in the world and typically reduces yield by 30 to 50 per cent. Other diseases and pests that cripple yields include a soil fungus, parasitic worms, weevils, and viruses such as the Banana Streak Virus, which lurks inside the banana genome itself.

Commercial growers can afford and rely extensively on chemical fungicides, often spraying their crops 50 times per year-the equivalent of spraying nearly once per week, which is about 10 times the average for intensive agriculture in industrialized countries. Chemical inputs account for 27 percent of the production cost of export bananas. Agricultural chemicals used on bananas for diseases and pests have harmed the health of plantation workers and the environment.

"If we can devise resistant banana varieties, we could possibly do away with fungicides and pesticides all together," said Frison. "In addition, resistant strains are essential for smallholder farmers, who cannot afford the expensive chemicals to begin with. When Black Sigatoka strikes, farmers can do little more than watch their plants die. Increased hunger can swiftly follow."

Banana Genome to Reveal Secrets of Plant Evolution

Following rice and Arabidopsis, the banana will be only the third plant sequenced. Comprised of just 11 chromosomes with a total of 500,000 to 600,000 base pairs, the banana genome is among the smallest of all plants and researchers expect quick results.

"If we've learned anything from genomics, it is how little we know about biology," said Claire Fraser, PhD, president of TIGR in Rockville, Maryland. "We expect that the banana genome sequencing will reveal surprising insights into the evolution of plants." J Craig Venter, PhD, head of the human-genome sequencing company Celera, is chair of the TIGR board.

"Bananas have unique characteristics that will provide researchers with a powerful model, capable of investigating fundamental questions with potentially widespread applications to agriculture," Frison said. He notes several areas of scientific interest:

  • Scientists will ultimately be able to compare the genome of wild bananas that reproduce sexually with those of asexual crop bananas. This should provide important insights in to how, and how quickly, plant genomes evolve.
  • Bananas originated in Asia, but several thousand years ago, humans introduced them to Africa. The wild bananas that remained in Asia continued to co-evolve with their pests, while the African arrivals left most of their pests behind. Comparing the genomes of wild Asian varieties with those of African cultivars will provide an uncommon look at the effects of disease agents on genome evolution.
  • The majority of cells of most organisms have two sets of chromosomes (one inherited from the female, the other from the male). In the laboratory, bananas can be grown with anywhere from one to six sets of chromosomes. Once the banana genome is known, scientists will be able to probe the effects of multiple chromosome sets on basic plant functions, such as how plants use and store carbon.
  • Bananas are the only known plant in which a virus (the Banana Streak Virus) imbeds pieces of itself into the banana's own DNA, only to pop out during times of stress, reassemble itself, and cause disease. The banana genome sequence should reveal just how this virus is able to strike when the plant is most vulnerable. It may provide a powerful new tool for targeted genetic transformation.
  • Note to newsdesk: Professor Heslop-Harrison is on 0116 252 5079 (direct) or 3381 (office).

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