Myxobacteria inoculation of wheat seeds – minor changes in the soil microbial community composition but potential for a reduction of take-all disease under greenhouse conditions

Abstract Background The price for wheat is driving the expansion of agricultural monocropping practices, which in turn facilitate the spread of phytopathogenic fungal infestation. Inoculating plants/ seeds with beneficial bacteria offers a sustainable alternative to chemical fungicides. Predatory myxobacteria are characterized by their production of various lytic secondary metabolites including fungicides. While their modes of action with prey are well studied, the direct application of myxobacteria in plants remains largely unexplored. Aims The aim of this study was to assess whether seed inoculation with myxobacteria has a general effect on plant growth and can control take-all disease caused by Gaeumannomyces tritici (Ggt) in wheat in vivo. Methods The inhibition potential of five different myxobacteria on ten soil-borne phytopathogenic fungi was examined in vitro. The effective myxobacteria, Haliangium ochraceum and Myxococcus virescens, were used as seed inoculants of winter wheat, which was grown for four weeks in soil infected with the pathogen Ggt in an in vivo greenhouse experiment. Results Myxobacteria inoculation did not impair plant growth (with and without Ggt infection), and M. virescens even showed a slight growth-promoting effect. Furthermore, myxobacteria inoculated plants showed a 50% reduction in symptoms of Ggt infestation compared to non-inoculated controls. Microbial (bacterial and archaeal) community profiling revealed no significant changes in rhizosphere and minor changes in bulk soil in response to myxobacteria inoculation. Conclusions Our study suggests that myxobacteria might be promising candidates for new plant-beneficial inoculants.