Uncovering metabolomic dysregulation in Lactuca sativa caused by exposure to nano- and microplastics (NMPs).

This work investigated the metabolic impact of nano- and microplastics (NMPs) in Lactuca sativa using controlled hydroponic exposures combined with non-targeted high-resolution mass spectrometry metabolomics. Polystyrene NMPs of four particle sizes (100, 200, 500, and 1000 nm) were tested across multiple concentrations. Multivariate analysis revealed clear metabolic discrimination between exposed and control plants, with smaller nanoparticles (100-200 nm) inducing the most substantial changes. Among the principal discriminant features, four were selected for in-depth characterization based on their statistical response, all consistently downregulated in NMP-exposed plants. α-Linolenic acid was confirmed at Schymanski Level 1, while three additional C18-class lipid-related features were annotated at Level 4. The four candidate metabolites point to disruption of polyunsaturated fatty acid (PUFA)-related pathways, with the C18H28O feature showing the strongest size-dependent response. In contrast, α-linolenic acid exhibited a more gradual response across particle sizes, suggesting a different interaction mechanism. Larger particles (500-1000 nm) induced markedly weaker effects, confirming the greater impact of smaller nanoparticles on PUFA downregulation. These findings illustrate the capability of HRMS-based untargeted metabolomics for evaluating NMP-induced metabolic disruption in food crops and its potential implications for plant health and food quality.