Polyethylene Microplastics Inhibit Peanut Nodulation via Metabolic and Transcriptional Pathways

Polyethylene (PE) microplastics (MPs) from residual mulch films are prevalent in peanut-cultivated soils, yet their specific effects on peanut nodulation remain unclear. This study investigated the impacts of PE-MPs at concentrations of 0.2%, 0.6%, and 1.0% on peanut nodulation. Results indicated that PE-MPs significantly reduced peanut nodule number. Transcriptome analysis revealed that all three concentrations of PE-MPs down-regulated nodulation-related flavonoids, promoted lignin deposition in cell walls, disrupted antioxidant system, and enhanced the accumulation of antimicrobial substances, collectively impairing peanut nodulation efficiency. These findings indicate that PE-MPs substantially compromise the symbiosis between peanut and rhizobia, and provide insights into their interference with plant–beneficial microbe interactions in contaminated soils.