Competition-driven phenotypic plasticity in Iron acquisition and aromatic utilization confers a fitness advantage to Pseudomonas putida in an Iron-limited rhizospheric environment

Iron scarcity poses a critical challenge for rhizospheric bacteria like Pseudomonas putida in the competitive rhizosphere. Despite its dependence on iron for essential functions such as root colonization, motility, and aromatic compound utilization, P. putida exhibits limited capability for heterologous siderophore utilization and primarily relies on the secretion of a single siderophore, pyoverdine. This study investigates the mechanisms by which P. putida acquires iron in an iron-limited, aromatic-rich, rhizosphere-like environment. Our findings demonstrate that P. putida exhibits significant phenotypic plasticity, dynamically modulating pyoverdine secretion in response to competitive pressures and substrate availability. This adaptive strategy optimizes energy expenditure and iron acquisition, providing a competitive advantage. Comparative gene expression analysis supports these observations, revealing the molecular underpinnings of this plasticity. Enhanced pyoverdine production driven by competition compensates for the bacterium's limited siderophore repertoire and facilitates rapid aromatic compound utilization, conferring a distinct fitness advantage in iron-deprived conditions. This study elucidates the complex interplay between competition, iron uptake, and aromatic compound utilization that underpins the rhizospheric success of P. putida.