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Understanding starch biosynthesis in order to control its structure, composition and properties.
S. ZEEMAN (1). (1) ETH Zurich, , , Switzerland

Starch is a vital plant product for society and the major nutritional component of cereal seeds. Learning more about its metabolism gives us options for cereal crop improvement by altering starch structure, properties and yields. Starch is primarily composed primarily of the branched glucan, amylopectin, which has an architecture that allows the formation of insoluble, semi-crystalline granules. Starch also contains a minor component, amylose, which has a major influence on the functional properties of the extracted starch. Starch synthesis requires multiple isoforms of the biosynthetic enzymes (starch synthases and starch branching enzymes) that initiate granules and elaborate amylopectin and amylose. Amylopectin crystallisation is facilitated by a specialised sub-class of the debranching enzymes, which are thought to selectively remove misplaced branch points. Despite this knowledge, starch biosynthesis is not fully understood and the process not yet been recreated in vitro or in a heterologous system. Although much progress has been made by studying starch crops directly, functional genomic and biochemical studies in model organisms can accelerate our understanding of known starch-metabolising enzymes and the discovery of new ones. This presentation will give an overview of recent advances in our understanding of both amylose and amylopectin synthesis.

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