ABSTRACT
This chapter focuses on the lipid metabolism in nonphotosynthetic plant systems other than leaves and oilseeds. It reviews fatty acid and glycerolipid metabolism in nonphotosynthetic plastids. The chapter illustrates the in vitro dependency of several different types of plastids on relatively standard exogenously supplied co-factors. One of the more important concerns regarding fatty acid biosynthesis in nonphotosynthetic plastids as compared to chloroplasts is the physiological or metabolic source of the high energy co-factors. For plastids that have restricted glycolytic carbon flow, pyruvate derived from cytoplasmic glycolysis could also serve as a source of carbon for fatty acid biosynthesis. In general, nonphotosynthetic plastids are comparable to chloroplasts in terms of their glycerolipid compositions and capacities for glycerolipid biosynthesis. Phosphatidyl-glycerol (PG) and phosphatidylcholine (PC) are the principal phospholipids, each comprising approximately 10 to 20% of the total glycerolipid. Nonphotosynthetic plastids can synthesize essentially all of their membrane glycerolipids.
