Endobacterial symbiont of Fusarium oxysporum f.sp. cubense and the pathogenicity of their symbiosis towards banana plantling

Abstract

Fusarium oxysporum f.sp. cubense (Foc), a causal agent of panama disease was reported carrying bacterial endosymbionts. This research aimed to identify the endobacteria in 7 Foc strains and to study their symbiosis effect on the Foc pathogenicity towards Ambon Kuning and Tanduk banana cultivars. The pathogenicity of endobacteria-Foc symbiosis were tested in vitro on banana plantling. Crude filtrate and biomass suspension that were produced by culturing each Foc strains for 21 days in static condition either in PDB (Potato Dextrose Broth) (Foc − ) or in antibiotics supplemented PDB (Foc +) were used as effectors. The Foc pathogenicity was stated as disease severity percentage on leaves and on rhizome. The result showed that all Foc strains contained endobacteria. Enterobacter sp. was hosted by Foc IPBCC 19.1427 and Izhakiella australiensis was in the hyphae of Foc IPBCC 19.1430. Enterobacter sp. affected Foc IPBCC 19.1427 virulence towards banana cv. Tanduk through effectors in the filtrate, while that towards cv. Ambon Kuning was unclear. Izhakiella australiensis did not affect Foc IPBCC 19.1430 virulence towards the two banana cultivars. The pathogenicity of Foc should further be verified, as the antibiotics given could not completely kill the endobacteria.