From banana plantation to global health

Leonard Bonapart

 

"Banana plantations in Africa, Asia and Middle America, are threatened by a leaf spot disease called Black Sigatoka disease. The export-banana, we eat for breakfast, lunch or desert could entirely disappear from the menu." This is a quotation by French Geneticist Emile Frisson, who chairs the International Network for the Improvement of the Banana and Plantain (INIBAP). He and other scientists are worried about the consequences fungi could have in the near future on global health.

 

The herbaceous Banana plant is of almost treelike size and originates from Southeast Asia. There are over 300 species, only a few of which are edible. Researchers suggest that banana was one of the first crops to be domesticated by man. It could therefore have existed for over ten thousand years. Throughout the world, the banana is the most popular fruit. In Uganda the word for banana (Matoke) is equal to the word for food. After rice, wheat and milk, it is the fourth most valuable source of food. In export, the banana ranks fourth among all agricultural commodities and is the most significant of all fruits, with world trade totalling $2.5 billion annually. Only 10% of the annual global output of 86 million tons enters the international market. Poor farmers in tropical Africa, America and Asia consume the rest of the harvest. For over a hundred years, fungi have been a menace to banana plantations. The Cavendish Bananas (that are used for export, originating in Taiwan) are sterile mutants of inedible natural plants. This makes it difficult to create new varieties that are resistant to the diseases by natural methods. The banana is very sensitive to not only fungi but also to other plant parasites. Other plant species are cultured and have a more diverse genetic basis because they are combined with wild species that are resistant to the pathogens. There are two economically important fungal diseases: Fusarium oxysporum, the cause of Panama-disease and Mycosphaerella fijiensis, causing Black Sigatoka disease.

 

According to professor Pierre de Wit; a Dutch professor in plant diseases associated to Wageningen University, the Black Sigatoka causing fungi is so aggressive that he finds immediate action necessary. Black Sigatoka, better known as black leaf streak, causes significant reductions in leaf area, yield losses of 50% or more. French Geneticist Emile Frisson stresses the importance of more research in culturing and genetically manipulating bananas and performing genomic research to prevent the disappearance of the banana. Such research is subsequently being performed in Leuven. Emile Frisson emphasizes that the work - funded in part by individual governments, the World Bank and other economic development agencies, focuses on increasing the harvest for small farmers, those more likely to be threatened by Black Sigatoka. For 14 years, scientists affiliated with INIBAP have been working at the Catholic University in the city of Leuven to increase banana productivity and eliminate the threat of Black Sigatoka. Black Sigatoka causes yellow-black spots on leafs of the banana plant. Firstly the leaves and eventu- ally the entire plant dies. In 1963 the fungi was first discovered in the Sigatoka valley on the Fiji Islands. In 1972 it was discovered in Honduras and in 1973 in Africa (Zambia). Now it's devastating effects can be found in plantations around the world.

 

Currently it is fought with potent chemicals that take a "tremendous toll" on the environment and the people that work on the plantations. The condition of Costa Rican banana workers has received worldwide attention with the case of over 6000 banana workers that became sterile by exposure to the pesticide di-bromo-chloropropane (DBCP), and whose effects on the reproductive system of women and mutagenic effects on subsequent generations, is only beginning to be investigated (bron: FORO EMAUS). Good research implies more strenuous efforts to save the banana.

 

Today, an international consortium announced that it hopes to sequence the entire banana genome as early as 2006. The Global Musa (Banana) Genomics Consortium says the project would take anywhere between 5 and 10 years depending on the desired accuracy, and cost up to $7 million a year, says geneticist Emile Frisson. By insertion of genes that could help protect the banana other researchers attempt to save the sweet fruit. However not all researchers believe the banana is in danger of extinction. Plant pathologists of the American Phytopathological Society (APS), an independent non-profit organisation of 5.000 researchers worldwide, say that it is not likely that bananas will really become extinct within the next decade. "Diseases such as Black Sigatoka will remain, which will cause major constraints to both export and subsistence production of banana," said Randy C. Ploetz, Professor at the University of Florida's Tropical Research and Education Center. "However it is unlikely that these problems will cause production to decrease greatly in the next decade, let alone that the crop will become extinct." According to Ploetz, Black Sigatoka affects diverse bananas used in subsistence agriculture, as well as the important Cavendish cultivars that are used in export production. It is a serious foliar disease, but does not kill plants and is well controlled in export plantations with fungicides. But it is these pesticides that cause environmental stress and an increase in the cost of the export of banana. As the long distant future of the banana remains insecure, biological research can add to ways in exploring how we can preserve this fruity sweet nutritious yellow wonder of nature. 

 

References

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