Quick, W.P., Department of Animal and Plant Sciences, University of Sheffield, Sheffield, United Kingdom;

Starch and sucrose are the major end-products of photosynthesis. Carbon fixed during photosynthesis is either retained in the chloroplast and converted to the storage carbohydrate starch or transferred to the cytosol in the form of triose phosphates and converted to sucrose. Sucrose, which is the major transport form of reduced carbon in higher plants, is then either stored in the vacuole or exported to other parts of the plant. Similarly transported sucrose is retained in sink tissues, or further metabolized to sustain cell maintenance and fuel growth or converted to alternative storage compounds (e.g., starch, fats). The relative type and size of these carbohydrate pools vary dramatically during tissue development, between different plant species, and within the same species subject to different environmental conditions and often determine the yield and quality of agricultural produce. Hence there has been considerable interest in the elucidation of the regulatory mechanisms that are responsible for such observed genetic and developmental differences. The direction of organic carbon from one tissue to another requires a metabolic coordination of both sucrose synthesis and degradation within specific tissues and often at remote sites. © 1996 by Marcel Dekker, Inc. All Rights Reserved.