Integration of metabolism in non-photosynthetic plastids of higher plants

Non-photosynthetic plastids are important subcellular sites for the assimilation of inorganic nitrogen and the biosynthesis of amino acids, starch and fatty acids. Unlike chloroplasts, all the metabolites for these processes have to be imported from the cytoplasm either directly or indirectly. Many of the intermediates for biosynthesis are generated by glycolysis and the oxidative pentose phosphate pathway within these organelles. In this paper we summarize what is Known about the regulation of oxidative oxidative and biosynthetic pathways within such plastids. Emphasis is placed (I) on metabolite transport; (2) on competition for ATP and reductant; and (3) on competition for hexose phosphate between biosynthetic and oxidative pathways.