Immune mechanism of oligochitosan-induced resistance toward potato virus Y in <i>Nicotiana benthamiana</i>

This study investigated the antiviral activity and molecular mechanisms of oligochitosan against potato virus Y (PVY) in Nicotiana benthamiana.The results demonstrate that oligochitosan exhibits significant anti-PVY activity, achieving a preventive efficacy of 54.7%.Biochemical analyses revealed that oligochitosan treatment enhances the activities of defense-related enzymes and stimulates hydrogen peroxide accumulation in N. benthamiana.Integrated transcriptomic and proteomic analyses identified key differentially expressed genes associated with reactive oxygen species signaling and the mitogenactivated protein kinase pathway, including PYL1, PP2C, OXI1, NDPK4, MAPKKK21 and POD4.Functional characterization demonstrated that oligochitosan specifically upregulates OXI1 expression while enhancing MAPKKK21 and NDPK4 transcript levels, thereby conferring enhanced PVY resistance.These findings establish that oligochitosan-induced plant defense against PVY operates primarily through ROS-mediated activation of the mitogen-activated protein kinase signaling cascade.This work provides novel insights into the molecular basis of the antiviral activity of oligochitosan in plant protection.