On the stabilization of plant lipid droplets: Dynamic interplay between oleosins and phospholipids

As the central organelles of lipid and energy homeostasis in plant seeds, lipid droplets (LDs) consist of a neutral lipid core, decorated by phospholipids (prominently phosphatidylcholines, PCs) and surfactant-like proteins (mostly oleosins, OLs). So far, the dynamic interplay between PCs and OLs at the LD interface remains unclear. The presented work addresses this knowledge gap by reconstituting oil-in-water emulsions stabilized by OLs and PCs using microfluidic systems. Our results show that the resistance to droplet coalescence is primarily provided by OLs. We further reveal that the addition of PCs alters the assembly of OLs at the interface, reducing the OL network density and interfacial elasticity, thereby rendering a weaker interface. In conclusion, our study suggests complementary roles, with OLs acting as the primary stabilizers while PCs playing a destabilizing role. This contrast likely contributes to the observed metastability of LDs and can be exploited to design stimuli-responsive emulsions. HIGHLIGHTSO_LIOleosins form an interfacial network that stabilizes the oil-water interface. C_LIO_LIPhosphatidylcholines globally weaken the oleosin network and promote droplet coalescence. C_LIO_LIMicrofluidics enables controlled reconstitution and real-time analysis of lipid droplets. C_LIO_LIOleosin-phospholipid interplay explains lipid droplet metastability and can guide the design of bio-inspired emulsions. C_LI