ABSTRACT
This chapter describes how biochemical genetics and biochemistry have been used together to study starch metabolism or carbohydrate metabolism. As starch is the principal storage carbohydrate of plants, the metabolism of starch is a central component in the balance of assimilates distribution. Starch is found in both source and sinks tissues. Many of the pathways for starch synthesis concentrate on the latter steps of synthesis and only consider a few enzymes. These pathways reflect the compartmentation in the cell and have much in common. Key enzymes for pathways are the adenosine diphosphate-glucose pyrophosphorylase, sucrose-P synthase, and three enzymes involved in the formation or breakdown of fructose-1,6-bisphosphate, namely 6-phosphofructokinase, fructose-1,6-bisphosphatase, and pyro-phosphate-dependent phosphofructophosphotransferase. As storage tissue develops, the synthesis and storage of sucrose and starch probably occur simultaneously. Translocated sucrose arriving at a storage tissue may be hydrolyzed to glucose and fructose during the unloading and movement into the storage tissue.
