Nitrogen-Doped Carbon Dots Enhance Plant Salt Stress Tolerance via Sphingolipid-Dependent Calcium Signaling

Soil salinization threatens global food security, making the development of strategies for improving plant salt stress tolerance an urgent research priority. Nitrogen-doped carbon dots (N-CDs), as carbon-based nanomaterials, have exhibited potential agricultural application value; however, the underlying mechanism by which they regulate plant salt tolerance remains elusive. In this study, N-CDs were synthesized via a hydrothermal method using citric acid and triethylenetetramine as precursors. Subsequent experiments were performed on Arabidopsis thaliana and apple “Orin” callus. The results demonstrated that N-CDs with amino-group-rich surfaces could enhance plant salt stress tolerance. Mechanistically, N-CDs induced sphingolipid/calcium channel protein-dependent Ca 2+ influx, which in turn activated the salt stress response pathway. Furthermore, we preliminarily detected the interaction between N-CDs and glycosylinositol phosphorylceramides (GIPCs) with a dissociation constant ( K d ) of 1.34 mM. Collectively, this study reveals the molecular mechanism through which N-CDs enhance plant salt tolerance via the “sphingolipid-Ca 2+ ” signaling pathway.