Co-inoculation of endophytic bacteria enhances hydroponic wheat performance and zinc biofortification through root exudates modulation

Purpose: , applied individually or as a SynCom, could improve wheat growth, Zn uptake, physiological performance, and root exudate modulation under hydroponic conditions. Methods: Wheat seedlings were grown under hydroponic conditions and inoculated with SaPA1 and SaBR2 individually or as a consortium, and their impacts on growth, Zn uptake, physiological characteristics, root morphology, and root exudate metabolomics were assessed after 30 days. Results: All inoculated treatments improved Zn uptake, wheat growth, plant height, and leaf photosynthetic performance relative to the control, with the SynCom showing the strongest overall effect. Zn concentrations increased by 42.49% in roots and 46.6% in shoots under the consortium treatment compared to the control. Zn accumulation was also significantly enhanced by endophytic inoculation, with the consortium producing the greatest increase, reaching about 6-fold in roots and nearly 3-fold in shoots relative to the control. Additionally, non-targeted LC-MS profiling revealed clear treatment-dependent shifts in root exudates, with the SynCom showing the strongest metabolic reprogramming and greater organic acid exudation. Conclusion: These findings show that endophytic bacteria derived from a Zn hyperaccumulator can improve wheat growth, Zn uptake, physiological performance, and root exudate remodeling under hydroponic conditions. Overall, the results support the potential of endophytic bacteria, especially as a SynCom, as a microbial strategy for Zn biofortification in wheat.