Abstract text: Endoplasmic Reticulum-Plasma Membrane contact sites (ER-PM CS) are nanodomains bridging the ER and PM membranes in close proximity. In Arabidopsis thaliana, the ER-PM CS tethering protein Synaptotagmin 1 (SYT1) is essential for resistance to abiotic and biotic stresses. Using Affinity Purification-Mass Spectrum (AP-MS), TurboID, and Localization of Proteins by Isotope Tagging (LOPIT), we identified Membrane Sterol Binding Proteins 1 and 2 (MSBP1 and MSBP2) as SYT1 interactors. MSBPs act as scaffold proteins to organize the cytochrome P450 metabolon (C4H, C3’H, and F5H) that synthesizes monolignols. Microscopy and protein interaction studies confirm that the SYT1 and MSBP1/2 interaction is spatially restricted to the ER-PM CS. Furthermore, syt1 mutant shows significantly deficient ectopic lignin deposition when treated with the cellulose inhibitor isoxaben, compared to wild-type plants. Thus, indicating that SYT1 function in ER-PM CS is critical for stress-induced lignification. Because monolignols can be exported to the cell wall via passive diffusion driven by high local concentration, we propose that the lignin biosynthesis metabolon localizes at SYT1-ER-PM CS to create a gradient expediting monolignol transport. This work highlights a novel function for ER-PM CS in coupling metabolic scaffolding with directional transport for cell wall reinforcement.