Title : Sustainable use of siderophore-producing rhizobacteria to enhance iron nutrition, chlorophyll stability, and stress tolerance in tomato plants
Abstract:
Iron (Fe) is an essential micronutrient for tomato (Solanum lycopersicum) growth, regulating chlorophyll biosynthesis, photosynthetic efficiency, respiratory metabolism, and key defense responses. However, Fe availability in soil is often extremely limited due to rapid oxidation and precipitation, which makes tomato plants highly susceptible to iron-deficiency chlorosis and associated stress sensitivities. Siderophore-producing Plant Growth-Promoting Rhizobacteria (PGPR) represent a sustainable biological strategy to overcome this constraint by mobilizing sparingly soluble Fe forms and improving plant nutrient acquisition under both optimal and stress-induced conditions. In this study, tomato plants were treated with selected siderophore-producing PGPR strains isolated from tomato rhizosphere soils. Comprehensive evaluations—including chlorophyll content (SPAD), phenological progression, biomass accumulation, and visual symptom scoring—were conducted under controlled greenhouse conditions. PGPR inoculation significantly enhanced Fe uptake, reduced chlorosis symptoms, and increased chlorophyll stability compared with uninoculated controls. Siderophore-rich strains also improved plant performance under abiotic stress scenarios, suggesting a dual benefit in nutrition and stress tolerance. Molecular analyses indicated the activation of Fe-related transport pathways and potential modulation of defense-associated genes, supporting an integrated physiological response induced by bacterial siderophores. Overall, our findings demonstrate that siderophore-producing microorganisms offer a promising, eco-efficient tool for improving Fe nutrition, boosting stress resilience, and enhancing overall vigor in tomato plants. This work contributes to developing sustainable microbial-based strategies for horticultural crop production.
