Diversity of root‐associated fluorescent pseudomonads as affected by ferritin overexpression in tobacco

Summary

This study examined how ferritin overexpression in transgenic tobacco, which increases rhizospheric iron accumulation and reduces iron availability in the soil, alters the diversity and functional traits of root-associated fluorescent pseudomonads. Isolates from the transgenic line were selected for greater iron-stress tolerance and stronger antagonism against the plant pathogen Pythium aphanidermatum, with some antagonistic effects dependent on siderophore-mediated iron acquisition and others operating through alternative metabolites. The findings suggest that plant iron status can shape beneficial rhizobacterial communities through selective pressure on iron-stress physiology.

Regional applicability

This is a fundamental microbiology study using a model organism (tobacco) under controlled laboratory conditions and does not directly address United Kingdom farming practices or field conditions. The mechanistic insights into plant–microbe–pathogen interactions may inform broader understanding of iron-related selection pressures in soils and rhizospheres, but transferability to UK cropping systems would require field validation.

Key measures

Pseudomonad isolate diversity (genotypic and phenotypic); iron stress tolerance (minimal inhibitory concentrations of 8-hydroxyquinoline); pyoverdine diversity (isoelectrofocusing); antagonistic activity against Pythium aphanidermatum in vitro; siderophore characterisation by mass spectrometry

Outcomes reported

The study characterized fluorescent pseudomonad communities and their diversity in rhizosphere, rhizoplane and root tissues of ferritin-overexpressing and wild-type tobacco, and assessed their iron-stress tolerance and antagonistic activity against Pythium aphanidermatum. Isolates from the transgenic line showed greater tolerance to iron depletion and enhanced pathogen antagonism, often mediated by siderophores.

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