Microplastics in agroecosystems: environmental fate, bioavailability and ecotoxicological impacts on soil-plant-microbe interactions

Microplastics (MPs; <5 mm) are emerging pollutants increasingly found in agricultural soils due to human activities. Their persistence, diverse properties, and interactions with co-contaminants affect pollutant bioavailability, soil health, and ecosystem functioning. MPs impair seed germination, root growth, and water and nutrient uptake, while evidence suggests their uptake and movement within plants, raising concerns about food chain contamination. They induce oxidative stress by increasing reactive oxygen species, disrupting photosynthesis, membrane integrity, and metabolism. In soils, MPs alter bulk density, porosity, aggregation, and water retention, affecting nutrient cycling, contaminant mobility, and microbial communities. They also provide surfaces for microbial colonization and biofilm formation, potentially promoting antibiotic resistance gene transfer. Interactions between MPs and pollutants such as heavy metals and pesticides can increase contaminant bioavailability and plant accumulation. Overall, MPs pose significant risks to agroecosystem health, emphasizing the need for long-term mechanistic studies to understand their environmental fate and ecological impacts.