Unraveling the synergistic role of ABA and ethylene in root lignin synthesis: A key molecular mechanism for tobacco response to PS-NPs using multi-omics approaches

The widespread of plastics poses health risks through the food chain. While plenty of studies show plants absorb it through roots, but research on root responses to it is limited. This study explored the molecular mechanisms of tobacco seedling roots response to different polystyrene nanoparticles (PS-NPs) concentrations using multi-omics approaches. The results from confocal laser scanning microscopy indicated PS-NPs accumulate in root was proportional to concentration. PS-NPs reduced fresh weight by 19.1, 37.0, and 49.7 % in accompanied by increasing ROS. It is noteworthy that the lignin content was also significantly influenced, exhibiting an increase at low concentrations of PS-NPs and a decrease at high concentrations of PS-NPs. Compared to the control, the lignin content is 1.02, 0.87, and 0.83 times that of the control, respectively. To clarify the molecular mechanisms influencing the lignin content, a joint analysis of transcription-metabolism was conducted. It was found that ABA-related metabolites and genes first increased then decreased. In contrast, ethylene, which promote lignin degradation, showed an upward trend. It is likely that the dynamic balance between ABA and ethylene may influence lignin synthesis under PS-NPs treatment. This contribution not only clarified the impact of PS-NPs on plant root growth but also elucidated the potential mechanisms of phytotoxicity. • Plant's absorption of MP/NPs may pose health risks to smokers. • Increased PS-NPs lead to stunted tobacco growth associated with rising ROS. • ABA signaling boosts lignin, while ethylene signaling inhibits growth at high concentrations. • Lignin strengthens root barriers to mitigate the effects of harmful substances.