Moreover, some sterols and sterol biosynthetic intermediates have been suggested to function as signaling molecules influencing transcription and signaling transduction pathways independent of BRs 5, 6. In addition to their structural role, sterols serve as a metabolic precursor to brassinosteroids (BRs), a group of steroid hormones that regulate a wide range of biological process 4. As important components of biological membranes, sterols interact with phospholipids and proteins within the membrane, thereby regulating membrane fluidity, permeability, and membrane protein functions 1РІР‚вЂњ 3. Sterols are isoprenoid-derived lipids with essential roles in cell structure, function, and physiology. Collectively, our data reveal a role of sterols in coordinating the synthesis of oil and oleosins and their assembly into LDs, highlighting the importance of membrane lipids in regulating LD biogenesis. Importantly, mutants deficient in these sterols also display reduced LD number, increased LD size and reduced oil content in seeds. Analysis of sterol pathway mutants revealed that deficiency in several РІв‚¬вЂ 5-sterols accounts for the phenotype. Here, we show that sterols are required for formation of oleosin-coated LDs in Arabidopsis. However, emerging evidence suggest that their formation is a spatiotemporally regulated process, occurring at specific sites of the endoplasmic reticulum defined by a specific set of lipids and proteins.

The mechanistic details of LD biogenesis remain poorly defined. They are typically composed of an oil core coated by a monolayer of phospholipids and proteins such as oleosins. Lipid droplets (LDs) are intracellular organelles critical for energy storage and lipid metabolism.

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