Transcriptome Analysis Reveals the Role of Trehalose in Response to Polyethylene Terephthalate Nanoplastics Treatment in Foxtail Millet ( <scp> <i>Setaria italica</i> </scp> ) Seedlings

Foxtail millet (<i>Setaria italica</i>), a drought-tolerant C4 model plant, faces increasing threats from polyethylene terephthalate (PET) nanoplastics in agricultural ecosystems. While prior studies indicate that PET nanoplastics induce reactive oxygen species (ROS) accumulation and impair crop productivity, the physiological mechanisms underlying plant responses remain unclear. This study investigates the role of trehalose metabolism in mitigating PET nanoplastic stress in foxtail millet. Transcriptome sequencing of seedlings treated with 1 g/L PET nanoplastics (3 and 7 days) revealed significant differential expression of genes linked to trehalose accumulation, hormone signaling, and metabolic pathways. Notably, genes associated with trehalose biosynthesis (<i>SiTPS</i>/<i>SiTPP</i>) and degradation (<i>SiTRE</i>) were dynamically regulated, suggesting trehalose homeostasis as a critical stress-response mechanism. Exogenous trehalose application effectively alleviated ROS damage under nanoplastic treatment, corroborating its protective role. Further WGCNA analysis indicated the potential involvement of ABA signal transduction and the MAPK signaling pathway in foxtail millet's response to PET nanoplastic stress. Additionally, our findings build on earlier observations that elevated leaf potassium content mitigates ROS but further highlight trehalose-mediated signaling as a complementary adaptive strategy. These results demonstrate that trehalose metabolism, ABA signal transduction, MAPK signaling pathway, and alongside ion homeostasis are integral to foxtail millet's resilience to PET nanoplastics, offering novel insights into plant stress adaptation and potential strategies for enhancing crop tolerance in contaminated environments.