Effects of bisphenol A on root traits and rhizosphere bacteria: exploring the link between rhizosphere bacterial and root growth.

Background: Bisphenol A (BPA), a widespread environmental pollutant, has been extensively studied for its effects on bacteria and plant, but its impact on rhizosphere bacterial communities and plant root traits is less understood. At the same time, the role of bacteria in helping plants resist adversity is widely recognized, but the relationship between BPA-induced with rhizosphere bacterial changes and root development is still unclear. Therefore, this study investigated the effects of varying BPA concentrations (1.5, 17.2, and 50 mg/L) on soybean root traits and rhizosphere bacterial communities, as well as the relationship between them.

Result: The results revealed that BPA exposure significantly altered root traits, with root length, surface area, volume, and tip numbers being suppressed at 50 mg/L, while lower concentrations (1.5 and 17.2 mg/L) promoted root elongation and thickening. Bacterial community composition shifted notably, with Bacillota increasing and Pseudomonadota decreasing in relative abundance across all BPA treatments. Alpha diversity, measured by richness and Shannon_e indices, increased slightly at lower BPA concentrations, while beta diversity (Bray_Curtis and UniFrac) analysis showed significant differences, particularly at 50 mg/L. Community assembly processes (βNRI and βNTI) were dominated by deterministic mechanisms at lower BPA concentrations but shifted toward stochastic processes at 50 mg/L. Correlation analysis revealed significant relationships between bacterial community dynamics and root traits (Principal component PC1 and PC2), with alpha diversity indices influencing root traits represented by PC2 and beta diversity indices showing a negative correlation with PC1.

Conclusions: BPA exposure not only alters root morphology and bacterial community structure but also highlights the intricate interplay between rhizosphere bacteria and plant roots under BPA stress. This study contributes to the theoretical understanding of plant-microbe interactions in contaminated environments and may inform future research on microbial involvement in plant stress responses.