REACTION OF Musa balbisiana TO BANANA BACTERIAL WILT INFECTION

Banana bacterial wilt (Xanthomonas campestris) is an emerging disease of bananas in Uganda. All banana cultivars grown are susceptible. Musa balbisiana, a wild banana relative exhibits a progenitor like resistance type reaction to banana bacterial wilt infection. The negative M. balbisiana disease reaction suggests it could be used to improve banana resistance to banana bacterial wilt disease. Screenhouse and field experiments were used to characterise the reaction of M. balbisiana to banana bacterial wilt infetion. Psang awak, a reference susceptible cultivar was used as a positive control. No disease development on M. balbisiana under field and controlled conditions was observed. In general, as early as two weeks after inoculation, significant differences (P 0.05) were observed between M. balbisiana and the susceptible banana cultivar, Psang awak (ABB). Time course analysis of the possible role of Pathogenesis related protein 2 (PR-2), Phenyl alanine ammonia lyase (PAL), Non-expressor of pathogenesis related gene (NPR1) genes in Musa balbisiana resistance reactions, revealed that only NPR1 was expressed 15 days after inoculation with X. campestris at 10^8 dosage. The expression of NPR1, a marker gene of the systemic acquired resistance plant defence system provides preliminary evidence that this may be the major form of resistance in Musa balbisiana to bacterial wilt infection.