Aim. Microbe-plant interactions (MPI) constitute an important aspect of ecology because of their significant influence on plant’s ability to withstand abiotic stress and infection. In comparison to proteobacteria and bacilli, the roles of streptomycetes in MPI remain poorly studied. Here, we elucidate some aspects of MPI between two model plant species, Hordeum vulgare and Lycopersicon esculentum, and several strains of Streptomyces lividans 1326 and S. ghanaensis ATCC14672. Methods. Microbiology, microscopy and molecular genetics were combined to reveal the MPI. Results. We demonstrate the colonization of H. vulgare and L. esculentum roots by different strains of S. ghanaensis deficient in production of either the antibiotic moenomycin or signaling molecule of the γ-butyrolactone type. The treatment of H. vulgare seeds with S. lividans spores increased the root biomass. Plants treated with 1,4-butyrolactone had no positive influence on plants, at milimolar concentrations this compound inhibited the root and shoot growth of L. esculentum. Conclusions. Roots of two mono- and dicot plants are colonized by Streptomyces; reporter gene uidA is useful to monitor the colonization. Under our experimental conditions the ability to colonize plants by streptomycetes was not affected by the deficiency in antibiotic or butenolide production.
Keywords: Streptomyces ghanaensis, moenomycinA, low-molecular weight signal compounds, root colonization.