Arabidopsis thaliana-Actinacidiphila interaction

How bacteria from the microbiota modulate the physiology of its host is an important question to address. Previous work revealed that the metabolic status of Arabidopsis thaliana was crucial for the specific recruitment of Streptomycetaceae into the microbiota. Here, the Arabidopsis-Actinacidiphila interaction was further depicted by inoculating axenic Arabidopsis with Actinacidiphila cocklensis DSM 42063 or Actinacidiphila bryophytorum DSM 42138(previously named Streptomyces cocklensis and Streptomyces bryophytorum). We demonstrated that these two bacteria colonize A. thaliana wild-type plants, but their colonization efficiency was reduced in a chs5 mutant with defect in isoprenoid, phenylpropanoids and lipids synthesis. We observed that those bacteria affect the growth of the chs5 mutant but not of the wild-type plants. Using a mass spectrometry-based proteomic approach, we showed a modulation of the Arabidopsis proteome and in particular its components involved in photosynthesis or phytohormone homeostasis or perception by A. cocklensis and A. bryophytorum. This study unveils specific aspects of the Actinacidiphila-Arabidopsis interaction, which implies molecular processes impaired in the chs5 mutant and otherwise at play in the wild-type. More generally, this study highlights complex and distinct molecular interactions between Arabidopsis thaliana and bacteria belonging to the Actinacidiphila genus.