Microplastics in the rhizosphere: unraveling plant–microbe–soil interactions and consequences for crop resilience

Microplastics (MPs), plastic particles smaller than 5 mm, are increasingly recognized as pervasive pollutants in terrestrial ecosystems, especially agricultural soils, which serve as long-term sinks. While early research prioritized aquatic environments, recent studies underscore the diverse pathways through which MPs infiltrate soils, via plastic mulching, wastewater irrigation, sewage sludge, compost, and atmospheric deposition. This review provides a comprehensive overview of emerging insights into MPs-plant-microbe interactions within soil systems, emphasizing both their complex ecological effects and key knowledge gaps. The main objective of this review is to consolidate current evidence on how MPs affect plant physiology and soil microbial dynamics, and to highlight methodological limitations impeding progress in this field. MPs exhibit variable but often detrimental effects on plant health, including delayed germination, inhibited growth, impaired photosynthesis, and disrupted nutrient uptake. These outcomes are largely driven by physical blockage, chemical leaching, and oxidative stress, and are influenced by MPs characteristics (polymer type, shape, concentration) and plant species traits. Interestingly, low MPs levels may occasionally improve root biomass through enhanced soil aeration and water retention, reflecting the context-dependent nature of MPs impacts. Crucially, MPs alter soil microbial communities, reducing beneficial microbes, promoting pathogens, and interfering with enzymatic functions, thereby indirectly undermining soil fertility and crop productivity. Disruption of symbiotic relationships, such as mycorrhizal associations, further compounds ecological stress. This review also identifies a pressing need for standardized MPs detection and toxicity assessment protocols. Advancing analytical tools and ecologically relevant models is essential for uncovering plant molecular responses and supporting sustainable agriculture in MPs-contaminated environments.