From Root Exudates to Eco-Corona: Mechanisms Shaping Nanoplastic Fate and Plant–Soil Interactions

Plastic contamination in agricultural soils constitutes an emerging threat to plant growth, nutrient acquisition, and food safety. Micro- and nanoplastics (NPs) elicit oxidative stress, perturb root morphology, and interfere with key physiological processes. Despite extensive studies in aquatic systems, the mechanistic understanding of NP behavior in soils, particularly the formation of soil-specific eco-coronas, remains limited. This review provides a mechanistic synthesis of current evidence on the role of root exudates, comprising proteins, amino acids, lipids, and low-molecular-weight metabolites, in modulating NP fate and plant responses within the rhizosphere. We delineate key processes, including exudate adsorption onto NP surfaces, eco-corona formation, aggregation, transport, root uptake, and species- and polymer-specific effects. Root exudation dynamically alters NP surface properties, mediates heteroaggregation, modulates mobility, and regulates interactions with plant roots. At the same time, NP exposure induces species-specific metabolic responses, including enhanced secretion of organic acids, stress-related metabolites, and secondary compounds (e.g., flavonoids). Despite extensive research in aquatic and hydroponic systems, mechanistic understanding of NPs behavior in soils, particularly regarding eco-corona formation and the modulatory role of root exudates, remains limited. This review synthesizes these insights to propose a conceptual framework linking eco-corona dynamics with root exudation processes, thereby providing a foundation for future soil-focused investigations.