Bacteria-derived N,N-dimethylhexadecylamine modulates the endophytic microbiome of Medicago truncatula in vitro

Beneficial rhizobacteria such as Arthrobacter agilis and Pseudomonas fluorescens produce N,N-dimethylhexadecylamine (DMHDA), a volatile organic compound that acts as a plant-microorganism signal, inducing bacterial motility and plant defense mechanisms. In the present study, Medicago truncatula seedlings were cultured in vitro and inoculated with the microbial fraction of soil with or without DMHDA, and DNA from Actinobacteria, Firmicutes, and α, β, and γ-proteobacteria were quantified using quantitative polymerase chain reaction to obtain a bacterial community profile of root and shoot endophytic compartments. In seedlings cultured without DMHDA, β-proteobacteria and α-proteobacteria were more abundant in root and shoot endophytic compartments, respectively. However, when seedlings were cultured with DMHDA, the proportion of Actinobacteria and Firmicutes increased in both compartments. These changes were dependent on the dose of DMHDA. We propose that DMHDA modulates the endophytic microbiome by inducing plant immune responses.