Multi-omics analysis reveals immune responses in tobacco leaves treated with polyethylene nanoparticles

As an emerging contaminant, nanoplastics (NPs) could enter plant tissues through roots and leaves, posing threats to plant growth. Majority of the earlier studies have focused on the toxic effects of NPs after their uptake and the potential non-toxicological biological impacts. We found that 20 nm polyethylene NPs (PE-NPs) could rapidly induce stomatal closure in tobacco leaves after 1 h of exposure, along with increased reactive oxygen species levels and up-regulated expression of pathogenesis-related genes. These responses were similar to those induced by pathogen-associated molecular patterns (PAMPs), as in case of response to pathogen recognition. Subsequent multi-omics integration analyses of transcriptome, proteome, metabolome, and phosphoproteome revealed convergent and divergent responses of tobacco leaves to PE-NPs and the tobacco pathogen Pseudomonas syringae pattern-triggered immunity (PTI) responses. Tobacco leaves responded to both elicitors in a similar manner at the transcriptome and proteome levels, exhibiting numerous similar PTI response patterns, but distinct at the metabolome levels. The differences might arise from elicitor-specific phosphorylation events during post-translational modification, which reshaped gene expression by modulating enzyme activity, leading to distinct metabolite profiles. Our multi-level regulatory network revealed the molecular framework by which NPs as abiotic stressors activated plant innate immunity, providing a novel perspective for understanding the ecological impacts of NPs.