It is now established that plants shape the structure of their microbiota through genetic or physiological control. The team led by Hubert Schaller at the IBMP asked the question whether plant isoprenoid (syn. terpenoid) profiles when modulated could help reshaping the microbiota. To answer this question, they used an Arabidopsis thaliana mutant called chs5/dxs1, carrying a weak allele of the gene encoding 1-deoxy-D-xylulose-5-phosphate synthase (DXS1), a key enzyme in the plastidial isoprenoid biogenesis. In a previous work, they demonstrated that the metabolic status of A. thaliana was crucial for the specific recruitment of Streptomyces into the microbiota.
In a new study published in PhytoFrontiers, the researchers of the team test the interactions between A. thaliana and two bacteria, Actinacidiphila bryophytorum (previously called Streptomyces bryophytorum) and Streptomyces cocklensis, isolated from moss (Bryophyta) or soil respectively. They have shown that these two bacteria colonize the seedling and influence the growth of A. thaliana. In collaboration with the bioorganic mass spectrometry laboratory in Strasbourg (LSMBO), a proteomic approach was developed using these gnotoxic plants (sterile plants inoculated with bacteria) and identified more than 2,500 plant proteins and around twenty bacterial proteins. The proteome of plants inoculated with these two strains is modulated in the presence of bacteria, suggesting that a specific interaction is established between Arabidopsis and the Streptomycetaceae. This work confirmed that the Streptomycetaceae–Arabidopsis interaction involves molecular processes involving the biosynthesis of terpenoids, phenylpropanoids and phospholipids. These molecules probably enable the wild plant to specifically recruit these Streptomycetaceae. This work is all the more interesting given that these bacteria are ubiquitously present in the microbiota of various plants and are known to play a role in promoting plant growth or protecting them against certain pathogens.
