Microplastics with different charges affect plant gene regulation and metabolism

Microplastics are plastic pollutants with a particle size of less than 5mm, which are widely detected
in environmental media such as atmosphere, water and soil.
Agricultural film is an important source of microplastics in facility vegetable fields, and plant leaves capture or even absorb microplastics settled in the air and enter the human body
through the food chain.
However, the molecular mechanisms by which plants absorb different electrical microplastics through foliar pathways have not been reported
.

The research group of researcher Wang Fang of Nanjing Institute of Soil Science, Chinese Academy of Sciences found the first-order kinetic release law of phthalate esters in agricultural films, established an evaluation method for the release of agricultural film phthalate esters on human health risks, and quantified the fluorescence intensity to show that electrostatic action and physical retention are the adsorption mechanisms
of different charged microplastics on typical soils 。 Based on this, fluorescently labeled polystyrene microplastics (about 0.
2μm), combined with laser confocal microscopy, environmental scanning electron microscopy, transcriptomics and metabolomics studies, it was found that the main channels for lettuce to absorb microplastics through foliar exposure were stomatal intake and cuticle pathways
.
The accumulation of positively charged microplastics in lettuce leaves was greater than that of negatively charged microplastics, and had greater effects on lettuce physiology and biochemistry, transcriptome and metabolome, including the decrease of biomass and photosynthetic pigments, the increase of reactive oxygen species and antioxidant enzyme activities, the differential expression of genes and the change
of metabolite profile.
In addition, the genes associated with circadian rhythm in lettuce leaves were upregulated with the increase of exposure level of positively charged microplastics, which led to significant enrichment
of this functional pathway.
The results provide direct evidence for microplastics to enter plants through foliar pathway, reveal the environmental effects of microplastics with different charges on plant growth from the molecular scale, provide a theoretical basis
for understanding the migration, attribution and ecological effects of phthalate esters and microplastics in the environment, and further evaluate the ecological risks of agro-film source phthalate and microplastics in the environment of facility vegetable fields.

The above research results have been published in Environmental Science & Technology and the Journal of Hazardous Materials, with doctoral student Yu Wang as the first author and researcher Fang Wang as the corresponding author
of the paper.
The research work was funded
by the National Key Research and Development Program.

Paper links: 1, 2, 3