Root exudates of Helianthus annuus enhanced Tetrabromobisphenol A derivatives transformation in rhizospheric soil: Insights from desorption behavior and bacteriome succession

Abstract

Substantial alterations in the rhizosphere induced by root exudates can significantly influence the environmental behavior of tetrabromobisphenol A derivatives (TBBPAs) in soil-plant interface. However, the empirical evidence regarding the impact of root exudates on the transformation pathways of TBBPAs is notably scarce. The present study, through pot experiment, integrated root metabolome analysis, desorption kinetics and high-throughput sequencing technology to elucidate the mechanism of how actual root secretions mediate the environmental fate of TBBPAs in the soil-plant system from both macro and micro perspectives. The pot experiment indicated that compared with the natural attenuation, Helianthus annuus cultivation significantly enhanced TBBPAs dissipation efficiency by 55.24-58.89% after 45 days remediation, while facilitating formation of β-scission, oxidative cleavage, and O-methylation products. Root metabolomic analysis revealed a substantial shift in root exudates exposed to TBBPAs, which in turn induced the enrichment of specific TBBPA-degrading bacterial genera in the rhizosphere, including Sphingomonas, Rhizomicrobium, Saccharibacteria_genera_incertae_sedis, Parcubacteria_genera_incertae_sedis, Gaiella, and unclassified_Xanthomonadaceae. Crucially, this study provided the first empirical evidence that root exudates significantly enhance TBBPAs desorption from soil, uncovering a key plant-microbe interaction mechanism behind phytoremediation. These findings advanced our understanding of rhizosphere-mediated transformation processes of organic pollutants and provided critical data for ecological risk assessment in contaminated soil ecosystems.