Proc. I. Int. Symp. on Banana and Plantain for Africa Eds. K. Craenen et al. Acta Hort. 540, ISHS 2000. 207 NON-CONVENTIONAL BREEDING APPROACHES FOR BANANA AND PLANTAIN IMPROVEMENT AGAINST FUNGAL DISEASES AT AECI B. Okole, C. Memela, S. Rademan, K.J. Kunert Mike Brunette R. & D. Department, AECI Ltd. Kynoch Plant Lab. Private bag X2 Box 406 Modderfontein 1645, South Africa Tzaneen 0850, South Africa Keywords : plant transformation, somaclonal variation, toxin selection Abstract The current research activities at AECI for the production of fungal-resistant bananas and plantains are presented. Genetic transformation and mutation breeding, as non- conventional breeding tools for plant improvement, are outlined and selection in vitro against a fungal toxin isolated from Mycosphaerella fijiensis is presented in more detail. An outlook about the commercial application and potential of these technologies is given. 1. Introduction Bananas and plantains (Musa spp.) are world-wide among the most important staple food crops. They are ranked fourth after rice, wheat and maize and they have an identical ranking on a global basis amongst export commodities in terms of gross value of production (CGIAR, 1992). The performance of bananas and plantains, like many other crops, can be affected by severe diseases and pests. Major pests and diseases that can affect banana and plantain are the banana borer, nematodes, black leaf streak (black sigatoka) and Panama disease. These diseases usually lead to economically significant food and income losses. Consequently, the largest single component in the cost of production of dessert banana and plantain in the tropics is disease control. Current control measures, which comprise approximately 40% of total production cost (Ganry, 1993), vary from cultural and biological to chemical control. Besides conventional breeding techniques and non-breeding control measures, bananas and plantains might be protected against severe biotic stresses by applying non- conventional breeding techniques. Non-conventional techniques that have been previously used by several research groups include genetic transformation, induced mutagenesis and somaclonal variation. At the Plant Biotechnology Section of AECI with its commercial tissue culture operation Kynoch Plant Laboratories formerly known as Tropical Technologies, we have recently initiated an ambitious R&D non-conventional breeding program. It is our overall objective to incorporate disease resistance to commercially interesting banana and plantain cultivars for local and international markets. As a first step in this program, we have specifically developed an interest in improving resistance of banana plants to fungal diseases with specific focus on the fungus Mycosphaerella fijiensis (Morelet) causing black sigatoka disease. This disease, which is among the major fungal diseases in continuous banana cultivation in tropical Africa, the Pacific Islands and in Latin America, is normally controlled by extensive application of systemic fungicides. In this paper, we report about the current status of our activities regarding the application of non-conventional breeding techniques to improve banana and plantain against fungal diseases.