Echinacea purpurea microbiota: bacterial-fungal interactions and the interplay with host and non-host plant species in in vitro dual culture

Important evidence is being reported on the antimicrobic and antagonistic properties of bacterial endophytes in Echinacea purpurea and their role in the modulation of plant bioactive compounds synthesis. Here, endophytic fungi were isolated from E. purpurea tissues, and the dual culture approach was applied to deepen insight into the complex plant-microbiome interaction network. In vitro experiments were carried out to evaluate the species-specificity of the interaction between host (E. purpurea) and non-host (E. angustifolia and Nicotiana tabacum) plant tissues and bacterial or fungal endophytes isolated from E. purpurea in vivo plants and to test the interaction between fungal and bacterial endophytes. A higher tropism towards plant tissue and growth was observed both for fungal and bacterial isolates compared to controls without plant tissue. The growth of all fungi was significantly inhibited by several bacterial strain that in turn were scarcely affected by the presence of fungi. Finally, E. purpurea endophytic bacteria were able to inhibit the mycelial growth of the phytopathogen Botrytis cinerea. Bacteria and fungi living in symbiosis with wild Echinacea plants interact with each other representing a potential source of bioactive compounds and a biocontrol tool.