Benzoxazinoid-mediated microbiome feedbacks enhance Arabidopsis growth and defense

Plants modulate their surrounding microbiome via root exudates and this conditioned soil microbiome feeds back on the performance of the next generation of plants. How plants can perceive this altered microbiome and modulate their performance in response to such microbiome feedbacks however remains largely unknown. We made use of two maize lines, which differ in their ability to exude benzoxazinoids, to condition two contrasting soil microbiomes in the same starting soil. Based on these conditioned soils we have established a model system withArabidopsis thaliana(Arabidopsis) to investigate the mechanisms of microbiome feedbacks. Arabidopsis plants grown on the benzoxazinoids conditioned soil developed larger rosettes, for which the soil microbiome was required. Arabidopsis roots also harbored differential bacterial communities. Further, these plants showed enhanced defense signatures in their shoot and were more resistant to the fungal pathogenBotrytis cinerea. We could establish Arabidopsis as a model to study benzoxazinoid-mediated microbiome feedbacks, which will allow future studies to investigate underlying mechanisms. Arabidopsis also responded with both improved growth and enhanced resistance to a complex benzoxazinoids conditioned microbiome, and we hypothesize that this simultaneous increase of growth and defense is mediated by priming of defenses.