Effects of polystyrene nanoplastics exposure on in vitro-grown Stevia rebaudiana plants

• Published in: Plant physiology and biochemistry Vol. 197; p. 107634
• Main Authors: Coman, Vasile, Scurtu, Violeta-Florina, Coman, Cristina, Clapa, Doina, Iancu, Ștefania D., Leopold, Nicolae, Leopold‬‬, Loredana-Florina
• Format: Journal Article
• Language: English
• Published: France Elsevier Masson SAS 01-04-2023
• Subjects: Diterpenes, Kaurane - metabolism; Fluorescence imaging; Glucosides - metabolism; Glycosides - metabolism; Hormesis; Microplastics - metabolism; Microplastics - pharmacology; Phytotoxicity; Plant Leaves - metabolism; Polystyrene nanoplastics; Polystyrenes - metabolism; Root uptake; Stevia - metabolism; Stevia rebaudiana; Stevia rebaudiana; Hormesis; Phytotoxicity; Fluorescence imaging; Root uptake; Polystyrene nanoplastics
• ISSN: 0981-9428; 1873-2690
• DOI: 10.1016/j.plaphy.2023.03.011

Nanoplastics (NPs) as environmental contaminants have received increased attention in recent years. Numerous studies have suggested possible negative effects of plants exposure to NPs, but more data are needed with various plants under different exposure conditions to clarify the underlying phytotoxicity mechanisms. In this study, we investigated the effect of polystyrene nanoplastics (PSNPs; 28.65 nm average diameter) exposure (10, 100 and 250 mg/L) on plant morphology and production of relevant metabolites (steviol glycosides, chlorophylls, carotenoids, and vitamins) of in vitro-grown Stevia rebaudiana plantlets. Additionally, we used dark field microscopy combined with fluorescence hyperspectral imaging for the visualization of internalized PSNPs inside plant tissues. At higher concentrations (>100 mg/L), PSNPs were shown to aggregate in roots and to be transported to leaves, having a significantly negative impact on plant growth (reduced size and biomass), while increasing the production of metabolites compared to controls, most probably because of response to stress. The production of steviol glycosides presented a biphasic dose-response suggestive of hormesis, with the highest values at 10 mg/L PSNPs (1.5–2.2-fold increase compared to controls), followed by a decline in production at higher concentrations (100 and 250 mg/L), but with values comparable to controls. These results are promising for future in vivo studies evaluating the effect of NP exposure on the production of steviol glycosides, the natural sweeteners from stevia.
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•High levels of polystyrene nanoparticles exposure are hazardous to stevia plantlets.•Plant morphology and production of secondary metabolites are significantly affected.•Fluorescence imaging reveals nanoparticle aggregates in plantlets' roots and leaves.