Droplets of lipid, 10-500 nm in diameter, found singly or in groups in the stroma of chloroplasts. They do not have an enclosing membrane but nevertheless retain their form when isolated from the stroma. Plastoglobuli from chloroplasts of actively photosynthesizing leaves contain various lipid and lipophilic compounds, e.g. galactolipids, quinones, and polyisoprenols, but no chlorophylls or carotenoids. As leaves become senescent, chloroplasts change to * chromoplasts and changes in the plastoglobuli occur. They accumulate carotenoid pigments and enlarge considerably until they become the dominant features in the chromoplasts. |
