Improvement of bananas for black sigatoka and panama disease resistance through genetic manipulation

Abstract

Bananas are a staple food in Eastern Africa, with 25.3% of the total world production. The production is, however, threatened by the presence of several diseases, of which the fungal diseases black sigatoka and Panama disease are the most important. With the development of embryogenic cell suspension cultures, the isolation of protoplasts therefrom and their successful regeneration, an invaluable vegetative material for genetic manipulation of bananas became available. The discovery of new types of antifungal proteins (AFP’s) and the cloning of their encoding genes provide a source of resistance to fungal diseases that can be introduced into plant cells by genetic engineering. Transformation techniques are currently under investigation. Electroporation of banana protoplasts have resulted in transient expression frequencies of more than 1% as visualized by the action of the β-glucuronidase (GUS) marker gene. Experiments with particle bombardment on cell suspensions have resulted in transient expression frequencies up to 3300 blue spots/0.5 ml cells, and stable transformants have also been selected. Optimisation of the cell suspension culture technique and transformation methodology is in progress.