Cereals reserves

Starch, a reserve polysaccharide widely distributed in plants, is the most important carbohydrate in the human diet. In plants, starch is present in the chloroplasts in leaves, as well as in fruits, seeds, and tubers. The starch content is especially high in cereal grains (up to 75% of the dry weight), potato tubers (approximately 65%), and in other plant storage organs. 

In the germination of cereal seeds, it was long known by brewers that if the embryo was excised (or dead) the endosperm would not be hydrolyzed and sugars would not be released. In 1960, Paleg showed that amylolytic activity in the embryo-less half could be fully restored in the presence of gibberellin. In other words, the substance that passed from the embryo to the endosperm (or rather, to the living cells of the aleurone layer that encloses the dead endosperm) induces there the synthesis of a-amylase which is responsible for hydrolysis of the stored starch reserves held in the endosperm. The extent to which the a-amylase was induced became another bioassay for gibberellin. 

It is not always clear whether cell-wall polysaccharides have a structural or reserve function because some, for example, the /3-glucans of cereal grains, may have dual roles. However, it is likely that the /3-glucans and other hemicelluloses in cell walls of tissues other than those in... 

Starch is second only to cellulose in natural abundance, and it is the major energy reserve in plants. The most important sources of starch are cereal grains, legumes, and tubers. The glucose polymers that make up starch come in two molecular forms, linear and branched. The former is referred... 

The nonphotosynthetic tissue ADP-Glc PPases of higher plants can be seen as two discrepant types (Table 1). The potato tuber ADP-Glc PPases from reserve tissues is typically activated by 3PGA and inhibited by Pi and thus grouped as class VIII (Table j) "phe ADP-Glc PPases from reserve tissues of cereals have been shown to exhibit distinctive regulatory properties, such as a lower or no sensitivity to activators. ... 

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