Role of Lipids in Chloroplast Biogenesis

Chloroplasts are plant organelles that develop the thylakoid membrane inside to perform oxygenic photosynthesis. The biogenesis of the thylakoid membrane requires coordinated synthesis and assembly of proteins, pigments and many photosynthetic cofactors with membrane glycerolipids. The lipid bilayer of the thylakoid membrane mainly consists of four lipid classes; monogalactosyldiacylglycerol (MGDG), digalactosyldiacylglycerol (DGDG), sulfoquinovosyldiacylglycerol (SQDG) and phosphatidylglycerol (PG), each of which has specific roles in biogenesis and maintenance of thylakoid membranes and photosynthesis. Galactolipids MGDG and DGDG constitute the bulk of membrane lipids in chloroplasts and are essential as major structural components of the thylakoid membrane. In addition to galactolipids, the thylakoid membrane requires a certain level of anionic lipids SQDG and PG for its function. Although SQDG and PG substitute for each other to maintain the amount of total anionic lipids in chloroplasts, PG has specific roles in photosynthesis that cannot be compensated by SQDG and galactolipids. In this chapter, we summarize roles of lipids in chloroplast functions with their biosynthetic pathways, which have been mainly established in Arabidopsis, and discuss an involvement of lipid biosynthesis in coordinated development of photosynthetic machinery during chloroplast biogenesis.