ABSTRACT: We conducted microbial inoculation and plant-derived root exudates validation experiments at four growth stages. Inoculation experiment demonstrated that co-inoculation optimized root morphology; promoted biomass (2.01-4.74 fold), Na+ (1.03-4.42 fold) and nutrient (1.04-13.94 fold) accumulation, antioxidase activities (1.19-5.09 fold), soil nutrient (1.05-3.79 fold), and desalination rate (1.93-3.29 fold); declined total dissolved salt (0.95-0.99 fold); revealed temporal regulation mechanism of co-inoculation as plant grew: root morphology (e.g., root length, etc.) regulated key exudates (e.g., flavonoids, etc.) to enrich key microbes (e.g., Nocardioides, etc.) to improve phytoremediation; and its synergistic regulatory mechanism at each stage: root morphology (e.g., root volume, etc.) effected multiple core exudates (CEs, e.g., terpenoids, etc.) to recruit diverse core microbiota (CMs, e.g., Proteobacteria, etc.) to improve phytoremediation. CEs repeated enriched same CMs (e.g., Chloroflexi, etc.) across stages but also specific enriched others (e.g., Gemmatimonadota, etc.). Validation confirmed that co-inoculation plant-derived root exudates modulated abundant CMs to affect plant growth. Overall, this study emphasized the significance of multiple exudates-microbes interactions in phytoremediation, providing new insight for microbial-assisted halophyte remediation of saline soil.
