Secreted Rhizobacterial β-Glucosidase Unlocks Coumarin-Mediated Root Iron Uptake

The root secreted metabolites of plants play a crucial role in shaping the composition and function of the root microbiota. In turn, the finely-tuned microbiota typically enhance the plant's ability to adapt to various environmental challenges. This interactive process in the rhizosphere is largely driven by chemical dynamics influenced by both the plant and microbial communities. To explore the structure-function relationship between root specialized metabolites (RSMs) and rhizosphere microbes, we collected root metabolome and microbiome data from Arabidopsis thaliana mutants with well-known metabolic pathways, all of which cultivated in alkaline soil. Specific associations between the rhizosphere microbiota and metabolome in each mutant, along with the observed phenotypes, illuminate the underlying mechanisms of their interactions. We uncovered a coumarin-mediated mechanism where β-glucosidase (belong to glycoside hydrolase family 3) secreted by enriched rhizobacteria alleviated iron deficiency for plants. These findings underscore the pivotal role of plant-microbe interactions in modulating metabolic dynamics, ultimately enhancing plant adaptability to environmental stresses. This study highlights the dynamic interplay between root metabolites and rhizosphere microbes, providing novel insights into plant-microbe interactions and potential application in sustainable agriculture.