Phosphatidylcholine Triggers Hydrogen Peroxide Signaling and Induces Pb Tolerance in Maize Seedlings

This study aimed to investigate the effects of phosphatidylcholine (PC) on maize seedlings exposed to lead (Pb) toxicity, focusing on antioxidant-system markers and Pb content analysis. A 7-d PC treatment resulted in improved plant growth, decreased lipid peroxidation and electrolyte leakage, increased activities of antioxidant enzymes (superoxide dismutase, catalase, glutathione reductase, and glutathione S-transferase), elevated levels of ascorbic acid and glutathione, and decreased accumulation of Pb. Furthermore, quantitative real-time PCR analysis demonstrated that exposure to Pb resulted in elevated expression levels of four genes encoding antioxidant enzymes (GR1, CSD1, γ-ECS, and CAT1), with these levels being further augmented by the presence of PC. The activities of phospholipase D (PLD) and NADPH oxidase (NOX) induced by Pb, as well as the production of H₂O₂, were augmented by PC within the initial 24 h. However, the growth-promoting effects of PC and its elicitation of an antioxidant response were hindered by the inhibition of NOX and PLD. The decrease in Pb accumulation after treatment with PC appears to be related to activation of the glutathione detoxification system through reactive oxygen species signaling triggered by PC. Overall, this study shows that PC treatment can improve antioxidant capacity and lower Pb accumulation in maize seedlings by activating PLD- and NOX-mediated H₂O₂ signaling. This method could help boost crop growth and ensure food safety in Pb-contaminated soil.