From Plastids to Lipid Droplets: Molecular Transporters Orchestrating Triacylglycerol Accumulation in Oilseed Crops

Oilseed crops are essential for global agriculture, industry, and nutrition, relying on complex pathways governing fatty acid (FA) and triacylglycerol (TAG) synthesis. While the enzymatic steps of TAG formation are well established, mechanisms of lipid trafficking between organelles remain poorly understood. This review summarizes recent advances in identifying lipid transporters involved in intracellular lipid movement and lipid droplet (LD) formation in oilseeds. Key protein families include non-specific lipid transfer proteins (nsLTPs), lipid droplet-associated proteins (LDPs), acyltransferases, ABC transporters, and plant VPS13 paralogs. Manipulating LDPs can enhance oil accumulation, yet the regulatory networks coordinating lipid transport and storage remain unclear. Recent studies highlight membrane contact sites (MCSs), especially between the endoplasmic reticulum (ER) and plastids, as critical hubs for lipid exchange. However, key questions persist regarding transported lipid species, ER–plastid tethering mechanisms, and redundancy among MCS proteins. Future research should prioritize identifying ER-to-LD transporters and expanding characterization of MCS-associated proteins. Integrating multi-omics, advanced imaging, and genome editing will be essential to uncover protein–lipid interactions regulating TAG trafficking and storage, enabling metabolic engineering strategies to improve oil yield and composition in oilseed crops.