Biosynthesis of the Pigment-Protein Complexes

In dark grown plants the proplastids are transformed into etioplasts. Following the formation and growth of the etioplast we observe first the appearance of a number of perforated prothylakoids, and later the formation of the prolamellar body. The prolamellar body increases in size as the time in darkness increases (1). During etioplast growth accumulation of protochlorophyllide (PChlide), bound to the PChlide-oxidoreductase, takes place. The rate of accumulation follows a sigmoidal curve, i.e., it is initially low, then increases, and finally stops after reaching a steady level (2)0 The PChlide is located in both the prothylakoids and the prolamellar body. Prothylakoids contain also a number of peptides, while the prolamellar body is rich in lipids (3,4). As the time in darkness increases further the structure of the etioplast is slowly degraded due to senescence.