Top banana fights fungal infection

For the past 30 years, the humble banana has been under attack from a fungal invader. Black sigatoga disease, caused by the fungus Mycosphaerella fijiensis, decimates fruit yields and reduces profit yields for some of the poorest farmers in East Africa.

Help is at hand, however, from a new genetically modified strain of banana resistant to the disease. The team from Uganda’s National Agricultural Research Laboratories Institute added genes for chitinase – a protein that breaks down the cell walls of the fungus – which prevents the fungus from entering the plants. The fungus, which can spread by airborne spores and when goods are exported, causes dark leaf spots which eventually kill the plant. In field trials, the bananas showed almost full immunity to the disease.

Currently, farmers have had to control the pest using aerial pesticide spraying – a technique that is reportedly harmful to both the environment and to the health of the local residents. The pesticide is often too expensive for many farmers. Resistence to the pesticide is also becoming evident in much of East Africa, making spraying even less economically viable. Genetically modified bananas may prove to be a cost effective method of maintaining crop yields, although further research is needed to calculate exactly how much of an advantage it will bring.

Settumba Mukasa, a crop scientist at Uganda’s Makerere University, points out the future implications of this research. “[The project] is a stepping stone for subsequent breeding programs and genetic engineering programmes. As a consequence of this project we can now do transformations of other varieties of bananas and other crop species.”