Microbial Synergism Couples Root Metabolic Remodeling with Exudation Dynamics in Liquidambar formosana

Plant–microbe interactions shape plant metabolism and rhizosphere processes, yet how root metabolic states are coupled to exudation remains unclear. Here, we show that inoculation with Serratia marcescens (NJ2D) and Funneliformis mosseae (BJ04), particularly in combination, enhances biomass (p < 0.005) and alleviates oxidative stress in Liquidambar formosana. Metabolomic analyses revealed a concerted remodeling of root primary metabolism, characterized by shifts in amino acids, organic acids, and sugars, alongside consistent enrichment of pentose and glucuronate interconversions. Concomitantly, root exudation was restructured, with increased release of carbon-rich metabolites. Notably, trehalose declined in both roots and exudates, indicating reduced osmoprotective demand and reallocation of metabolic resources. Together, these findings demonstrate that microbial inoculation reshapes root metabolism and exudation patterns in L. formosana, linking plant physiological responses with rhizosphere processes and potentially strengthening plant–microbe feedbacks.