Abstract: Human lysozyme (HL) inhibits Fusarium oxysporum (FocR4) growth in vitro. To obtain transgenic bananas (Musa spp.) that are resistant to Panama wilt (F. oxysporum), we introduced an HL gene that is driven by a constitutive cauliflower mosaic virus 35S promoter into the banana via Agrobacterium-mediated transformation. PCR confirmed that 51 transgenic plants were obtained. The development of Panama wilt symptoms were examined after the plants had been grown in pots. The non-transgenic plants developed typical fusarium symptoms 60 d after FocR4 inoculation, whereas 24 of 51 transgenic plants remained healthy. The transgenic banana plants that showed resistance to FocR4 in the pots were then planted in a field that was heavily infected with FocR4 for further investigation. Eleven of 24 plants developed symptoms before bud emergence; another 11 plants showed symptoms after bud emergence and the remaining two plants, H-67 and H-144, remained healthy and were able to fruit. Northern blotting analysis demonstrated that H-67 and H-144, bearing the strongest resistance to Panama wilt, had the highest level of HL expression and that the expression of HL was well correlated with the FocR4 resistance of transgenic plants. We conclude that Agrobacterium-mediated transformation, with the assistance of particle bombardment, is a powerful approach for banana transformation and that a transgenic HL gene can cause resistance of the crop to FocR4 in the field.

Key words: Agrobacterium-mediated transformation, Fusarium oxysporum, human lysozyme, Panama wilt disease, particle bombardment, transgenic banana.