ENDOPHYTIC BACTERIA: INDUCED SYSTEMIC RESISTANCE ENHANCES BANANA DEFENSE AGAINST BUNCHY TOP DISEASE

Abstract

Bunchy top virus is a pathogenic agent that drives banana bunchy top disease, causing yield losses that can reach up to 100% within 21.6 days post-infection. The use of endophytic bacteria to induce systemic resistance has the potential to control this virus. This study evaluated the efficacy of four endophytic bacteria i.e. Bacillus velezensis, Serratia sp., Enterobacter sp., and Stenotrophomonas sp., for their capacity to elicit systemic resistance in two banana cultivars (Kepok and Cavendish) under laboratory and greenhouse conditions. A factorial completely randomized design was employed, with two factors: banana cultivar (Kepok, Cavendish) and bacterial treatment (B. velezensis, Serratia sp., Enterobacter sp., Stenotrophomonas sp.) plus two non-inoculated controls, each with four replications. Data were analyzed by analysis of variance (ANOVA) followed by Duncan’s multiple range test (DMRT) at α = 0.05 to identify significant differences. Key findings show that Enterobacter sp. and Stenotrophomonas sp. significantly reduced disease severity index (DSI) to 10.4% and the area under the disease progression curve (AUDPC) to 21.8 in the Cavendish cultivar. Across cultivars, endophytic bacteria elevated levels of defense-related secondary metabolites, including phenolics, peroxidase activity, saponins, and tannins, indicating induced systemic resistance. Collectively, B. velezensis, Enterobacter sp., and Stenotrophomonas sp. effectively promote systemic resistance in banana via enhanced accumulation of these secondary metabolites.