Trichoderma brevicompactum and Pseudomonas fluorescens form a cross-kingdom consortium to enhance iron acquisition in calcareous soil

Iron limitation in calcareous soils restricts plant growth. Although Trichoderma species have been reported to enhance Fe availability by modulating rhizobacteria, the mechanisms remain unclear. Trichoderma brevicompactum TB2 inoculation in natural soil enhanced plant biomass and Fe nutrition compared to its inoculation in sterilized soil. The 16S rRNA sequencing revealed that TB2 restructured the microbial community. Through analysis of shared, specialist, and enriched ASVs, we identified a key ASV49. An isolated strain, Pseudomonas fluorescens PSE180, exhibited 100% sequence identity to ASV49. In-vitro assays demonstrated that no antagonism was observed between PSE180 and TB2, and 180T was efficient in siderophore production and Fe solubilization. We constructed a cross-kingdom consortium 180 T which promoted plant growth and improved Fe nutrition in pear, tomato and peanut. The PSE180 was effective in enhancing soil available Fe and plant Fe accumulation. TB2 enhanced plant biomass, but its effect on Fe nutrition was less pronounced than that of PSE180. The 180 T consortium exhibited complementary effects, with TB2 primarily improving plant growth and PSE180 promoting Fe-stabilization and bioavailability, thereby offering dual benefits for multiple plant species. These findings provide a framework for developing novel microbial consortia as an effective strategy for alleviating Fe-deficiency in crops. Trichoderma-Pseudomonas consortium enhances plant growth and Fe bioavailability via complementary mechanisms, offering an effective strategy to alleviate Fe-deficiency in calcareous soils.