Unveiling the sustained effects of plant root exudates on soil microbiome and resistome and the related functional traits

Investigating the transmission mechanisms and influencing factors of antibiotic resistance genes (ARGs) in the soil-plant continuum is vital for mitigating ARG contamination and safeguarding plant and human health. Rhizosphere soil serves as a crucial interface for ARG propagation and transmission; however, it is unclear whether and how plant involved in regulating ARGs in their rhizosphere environment. Root exudates acting as vital links in the plant-soil-microbe interaction. Here, we examined the fluctuating patterns of the resistome and mobile genetic elements (MGEs) following exposure to four types of common root exudates: amino acids (AAs), sugars, long-chain organic acids (LCOAs), and short-chain organic acids (SCOAs). AAs exerted a rapid and pronounced effect, leading to a significant elevation in total ARG and MGE abundance by 3.18-fold and 21.06fold, respectively, compared to the control group by day 7. Conversely, the impact of sugars manifested gradually over time. The influence of AAs and sugars persisted beyond 240 days post-treatment cessation. Importantly, the proliferation of ARGs was closely linked to the enrichment of plant growth-promoting bacteria (PGPBs) such as Pseudomonas, Cupriavidus, Azospirillum, Variovorax, and Ensifer. Functional analysis revealed that the potential features of ARGs and MGEs were associated with cell wall/membrane/envelope biogenesis, cell motility, and inorganic ion transport. This study offers novel insights into the factors influencing the dynamics of ARGs in the plant rhizosphere and may contribute to ecologically sustainable agricultural practices.