Effects of micro(nano)plastics on higher plants and the rhizosphere environment

Microplastic/nanoplastic (MP/NP) pollution has emerged as one of the world's most serious environmental issues, with the potential for grave consequences for ecosystems and human health. This review summarizes the current literature on the impacts of MPs/NPs on higher plants to reveal their phytotoxicity. MPs/NPs can be absorbed into plant roots and then enter and translocate to other tissues by transpirational pull. The interaction between plastic particles and plants not only causes oxidative stress but also induces adverse impacts on photosynthesis, metabolism, genetic expression, and other growth parameters. Furthermore, the combination of MP/NP pollution with other contaminants makes the joint effect more complex. The phytotoxicity of MPs/NPs depends on the characteristics of the plastic particles (exposure dose, size, shape, type, age, and surface charge) and of the plants (species, tissues, and growth stage). The ecotoxicity of MPs/NPs in plant species' surrounding habitats is also discussed. MPs/NPs can alter soil characteristics such as soil structure, water holding capacity, and pH in the rhizosphere. In addition, the rhizosphere microbial community composition and diversity were observed to change in the presence of MPs/NPs. Therefore, MPs/NPs can indirectly affect plant growth by changing the soil properties and the microbial community. In addition, suggestions for future study directions were also given. In summary, this review highlights the potential effects of MPs/NPs on higher plants and the surrounding environment and calls for additional studies to be carried out on the impact of plastic particles on the ecosystem and human health.