Siderophores: chemical threads of rhizosphere health.

Rhizosphere microbiomes are central to plant nutrition, pathogen suppression, and rhizosphere health, yet their functions remain difficult to predict from taxonomic composition alone. We argue that microbial siderophores offer a chemically explicit route from taxonomic associations to trait-based rhizosphere ecology. These structurally diverse iron-chelating metabolites link iron mobilization to ecological interactions across microbial, plant, and soil-fauna interfaces. In microbe-microbe systems, siderophore structure-receptor compatibility provides a well-established mechanism underlying resource sharing, competitive exclusion, and pathogen suppression. At plant and nematode interfaces, siderophore functions are increasingly evident, although recognition mechanisms remain less resolved. A siderophore-centered perspective can help move rhizosphere microbiome research from descriptive associations toward predictive, testable, and context-specific ecological engineering.