Abstract
Ralstonia solanacearum infects both plants and fungi. The phc quorum-sensing (QS) system of Ralstonia is important for parasitism of plants, because it enables invasion and proliferation within the host by ensuring appropriate activation of the QS system at each stage of infection. In this study, we confirmed that ralstonin A is important not only for Fusarium oxysporum (Fo) chlamydospore induction but also for Ralstonia biofilm formation on Fo hyphae. Exopolysaccharide I (EPS I) is also essential for biofilm formation, while the phc QS system controls the production of the factor. The present results advocate a new QS-dependent mechanism by which a bacterium invades a fungus.
