Effects of microplastics on the plant-arbuscular mycorrhizal fungal symbiotic system: type, size, and concentration

Arbuscular mycorrhizal fungi (AMF), serving as a key interface for plant-soil interactions, have ecological responses to pollutants such as microplastics, that directly impact the health and stability of the plant-soil system. This article systematically reviews the ecological effects and underlying mechanisms of microplastic type, particle size, and concentration on the plant-AMF symbiotic system. Research indicates that microplastics exert complex influences on the colonization process and functionality of AMF by altering soil physical structure, chemical properties, and microbial communities, thereby indirectly or directly affecting plant growth and stress resistance. Overall, non-biodegradable microplastics can indirectly influence plant growth, AMF colonization and community's C-S-R (Competitor-Stress tolerator-Ruderal) strategy by modifying soil structure or adsorbing pollutants, and plant recruitment of mycorrhizal types. The impact of biodegradable microplastics on plants increases with the degree of degradation, and their impact on plant and AMF community structure is significantly stronger than that of non biodegradable microplastics. Nanoplastics (< 0.1 μm), due to their greater ability to penetrate biological membranes, generally exhibit higher toxicity to the plant-AMF system compared to micron-sized particles. The effects of microplastics are highly dosage-dependent. Low concentrations (< 1% w/w) may stimulate AMF colonization, whereas medium to high concentrations (1-5% and above) typically inhibit mycorrhizal symbiosis and reduce host plants growth. Although preliminary progress has been made in current research, it is necessary to further reveal its molecular mechanism and explore both the combined pollution effects and the potential of AMF in the remediation of microplastic co-contamination.