Abstract

Fusarium oxysporum f. sp. cubense (Foc) is one of the major threats to dessert banana (Musa spp.) production. In Uganda, ‘Sukali Ndiizi’ is one of the most popular dessert banana cultivars and it is highly susceptible to Fusarium wilt. Development of resistant cultivars through transgenic approaches has shown to offer one of the most effective control options for most diseases. The transgenic approaches for providing plant disease resistance have mainly been through either enzymatic destruction of pathogen structures, neutralization of pathogen and its products or production of metabolites that eventually kill the pathogen. However in recent years, methods that prevent cell death of host plant after infection especially for necrotrophic pathogens like F. oxysporum have registered success in providing resistance in several crops. We investigated whether the transgenic expression of a programmed cell death inhibition gene in Sukali Ndiizi could be used to confer Fusarium resistance to Foc race 1. Embryogenic cell suspensions of cv. ‘Sukali Ndiizi, were stably transformed with a synthetic, plant-codon optimise mCed-9 gene. Twenty-eight independently transformed plant lines were regenerated. The lines were inoculated with Foc race 1 and observed for 13 weeks in small-plant glasshouse. Three transgenic lines showed significantly lower internal and external disease symptoms than the wild-type susceptible ‘Sukali Ndiizi’ banana plants used as controls. This is the first report from Africa on the generation of Fusarium wilt tolerant transgenic ‘Sukali Ndiizi’, a very popular but rapidly diminishing African dessert banana.

Key words: Fusarium wilt, banana, Sukali Ndiizi, Fusarium oxysporum f. sp. Cubense race 1, programmed cell death, disease resistance.

Abbreviation

CTAB, Cetyltrimethylammonium bromide; PCR, polymerase chain reaction; RT-PCR, reverse transcription - polymerase chain reactions; dNTPs, deoxynucleoside 5’-triphosphates; DNA, deoxyribonucleic acid; cDNA, complementary DNA; PDA, potato dextrose agar; LSI, leaf symptom index; RDI, corm discolouration index; DSI, disease severity index; ANOVA, analysis of variance.