RESUMO
The bacterial wilt caused by Ralstonia solanacearum is a destructive plant disease globally. Since a completely non-biological control measure could be a matter of environmental concern, investigations of developing eco-friendly strategies are required to control this phytopathogen. Attenuation of the bacterial virulence in addition to destroying the pathogen may be an alternative and overarching approach to control this disease. In this study, we have explored the potentiality of a vertically transmitted endophytic fungus Penicillium sp. PM031 isolated from stem of in vitro grown, wilt susceptible tomato cultivar to control this phytopathogen. The endophytic fungus was unable to inhibit the bacterial growth during direct confrontation in co-culture system; rather its growth and extracellular secretion were affected by the bacterium. Interestingly, the PM031-derived endo-metabolites, containing ~80% of lipid molecules, showed the dose-dependent growth inhibitory effect against R. solanacearum. Metabolite treatment with a concentration of 2500 and 5000 µg/ml significantly inhibited the bacterial growth 24.72% and 64.31%, respectively. Higher concentrations of endo-metabolite treatment exhibited antibacterial activity by rupturing cellular membranes. Furthermore, the endo-metabolites negatively influence the virulence factors necessary in early phases of bacterial infection, such as motility and biofilm formation. Our study highlights even if an endophytic fungus associated with the susceptible host plant cannot tackle R. solanacearum directly, its lipid-rich metabolites have potential to attenuate the virulence of phytopathogen. We believe this study can be a stepping stone to develop suitable formulations to control the bacterial wilt in a sustainable way, which will reduce excessive uses of synthetic bactericides.