Microplastics reduce nitrogen uptake in peanut plants by damaging root cells and impairing soil nitrogen cycling

Microplastic (MP) pollution severely impairs the sustainable development of modern agriculture. However, the mechanisms underlying the effects of MP contaminants on nutrient cycles in agroecosystems are poorly understood. In this study, we examined the impacts of two types of MPs, polypropylene (PP) and rubber crumb (RC), on nitrogen (N) transformation and N cycling in soil-peanut system. High concentrations of PP (1% w/w) and RC (1% w/w) inhibited vegetative growth and N uptake in peanut plants by damaging root cells and disturbing soil N cycling. These MPs damaged the plasma membranes of root cells and caused oxidative stress, as evidenced by the decreased number of xylem vessels, which in turn inhibited N uptake by roots. Integrated metagenomic and metabolomic analyses revealed that the differential soil metabolite levels in response to MP treatment affected the microbial community structure in the rhizosphere and the expression of key N cycling-related genes, resulting in altered N transformation and the decreased availability of N in rhizosphere soil. These findings provide the first evidence of the effects of MPs on N uptake in peanut plants and shed light on the importance of rational management of MPs for crop growth and yield in agroecosystems.