Starch synthesis in cereal grains

Abstract

In this review, we consider how starch is made in the developing endosperms of themajor cereal crops, wheat, maize and rice and how this process is controlled. We describe how carbohydrate is supplied to the endosperm, how the endosperm develops and the pattern of starch accumulation in the developing endosperm. The nature of starch in cereals in terms of granule morphology, the internal structure of granules and the structure of the glucan polymers which comprise starch is described. We review the current understanding of granule and polymer initiation and synthesis giving detailed information about the properties of the enzymes involved including the roles of the multiple isoforms of several of these enzymes. We concentrate on the nature and importance of the cereal-endosperm-specific pathway of starch synthesis involving the production of the substrate for starch synthesis, ADPG in the cytosol rather than the plastid. Finally, we give a summary of our current understanding of the control of biochemical pathways in general and of starch synthesis in endosperms in particular. © 2003 Elsevier Ltd.