Rhizobacterial functional assemblies modulate accumulation of phthalates in choysum (Brassica parachinensis L.)

Rhizomicrobiomes exhibit dynamic adaptability in their structural and functional compositions in response to environmental stressors, playing pivotal roles in modulating host plant tolerance and growth. Nevertheless, the responses of rhizomicrobiomes to pollution stress remain poorly understood. In this study, we investigate how di(2-ethylhexyl) phthalate (DEHP), a widespread soil contaminant, alters the rhizomicrobiomes of two choysum (Brassica parachinensis L.) varieties and how these stress-regulated microbial communities contribute to the distinct response patterns between the low-accumulation variety (LAV) and the high-accumulation variety (HAV).

The two choysum varieties exhibited differential recruitment of bacterial taxa in response to DEHP. The DEHP-sensitive LAV variety preferentially recruited DEHP-degrading bacteria, adopting an "avoidance-like" pattern to minimize DEHP accumulation. In contrast, the DEHP-tolerant HAV variety recruited plant growth-promoting bacteria, prioritizing growth regardless of DEHP accumulation. Synthetic microbial communities (SynComs) constructed from variety-specific isolates, along with corresponding cross-inoculation experiments, confirmed preferential colonization within host plants and the resulting phenotypic outcomes. These findings suggest that variety-specific rhizomicrobiome assembly confers distinct patterns in response to DEHP contamination, offering a potential mitigation approach to enhance food safety.

This study demonstrates variety-specific response patterns to soil organic pollutant (DEHP) from the perspective of rhizosphere microbial assembly, and establishes a direct link between DEHP accumulation phenotypes and functionally divergent rhizobacterial assemblies validated by SynCom experiments. Video Abstract.