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The diurnal metabolism of leaf starch

Citation

Zeeman, SC and Smith, SM and Smith, AM, The diurnal metabolism of leaf starch, Biochemical Journal, 401, (1) pp. 13-28. ISSN 0264-6021 (2007) [Refereed Article]

Copyright Statement

Copyright 2007 Biochemical Society

DOI: doi:10.1042/BJ20061393

Abstract

Starch is a primary product of photosynthesis in leaves. In most plants, a large fraction of the carbon assimilated during the day is stored transiently in the chloroplast as starch for use during the subsequent night. Photosynthetic partitioning into starch is finely regulated, and the amount of carbohydrate stored is dependent on the environmental conditions, particularly day length. This regulation is applied at several levels to control the flux of carbon from the Calvin cycle into starch biosynthesis. Starch is composed primarily of branched glucans with an architecture that allows the formation of a semi-crystalline insoluble granule. Biosynthesis has been most intensively studied in non-photosynthetic starch-storing organs, such as developing seeds and tubers. Biosynthesis in leaves has received less attention, but recent reverse-genetic studies of Arabidopsis (thale cress) have produced data generally consistent with what is known for storage tissues. The pathway involves starch synthases, which elongate the glucan chains, and branching enzymes. Remarkably, enzymes that partially debranch glucans are also required for normal amylopectin synthesis. In the last decade, our understanding of starch breakdown in leaves has advanced considerably. Starch is hydrolysed to maltose and glucose at night via a pathway that requires recently discovered proteins in addition to well-known enzymes. These sugars are exported from the plastid to support sucrose synthesis, respiration and growth. In the present review we provide an overview of starch biosynthesis, starch structure and starch degradation in the leaves of plants. We focus on recent advances in each area and highlight outstanding questions.

Item Details

Item Type:Refereed Article
Keywords:starch, photosynthesis, starch metabolism
Research Division:Biological Sciences
Research Group:Plant Biology
Research Field:Plant Physiology
Objective Division:Expanding Knowledge
Objective Group:Expanding Knowledge
Objective Field:Expanding Knowledge in the Biological Sciences
Author:Smith, SM (Professor Steven Smith)
ID Code:101510
Year Published:2007
Web of Science® Times Cited:224
Deposited By:Plant Science
Deposited On:2015-06-25
Last Modified:2015-09-24
Downloads:0

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