Activity and Multiple Forms of Hydrolytic Enzymes in Germinating Sugar Beets (Beta vulgaris L.)

The perisperm of seeds of Agrostemma githago contains starch reserves which constitute 40% of the dry weight of the mature seed. These starch reserves were mostly broken down between 48 and 96 h after initiation of imbibition. (Germination occurred after 24 h.) The mode of starch degradation showed close parallels with the breakdown of the starchy endosperm in cereals. Thus, between 24 and 96 h the cotyledons secreted α-amylase (EC 3.2.1.1) whereas other degradative enzymes in the perisperm, β-amylase (EC 3.2.1.2) and maltase (EC 3.2.1.20), appeared to originate in the perisperm itself. Cotyledons secreted similar levels of α-amylase in the presence and absence of exogenous starch, indicating that secretion is an internal developmental event of the embryo. By isoelectric focussing the secreted α-amylase was separated into two isoenzymes. In the cotyledons, several other starch-degrading isoenzymes were present but were not secreted.

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Mobilisation of storage reserves during germination and early seedling growth of sugar beet

Lawrence

Halmer

Bowles

1990

Physiologia Plantarum

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The principal storage reserve of sugar beet seeds is starch, which is localised in the perisperm. Additional storage reserves include the seed proteins, albumins, globulins and glutclins, which are exclusively located in the embryo. Soluble sugars are also detectable in all the organs of the mature seed. The time‐course of reserve mobilisation in the different organs of the sugar beet (Beta vulgaris L. cv. Regina) seed during germination and early seedling growth is documented, with particular reference to changes in (a) activities of hydrolases: a‐amylase, β‐amylase, and α‐glucosidases; (b) levels of carbohydrates and (c) proteins. Amylase activities increase substantially in both cotyledons, as well as the perisperm, whereas the increase in α‐glucosidase activities is largely confined to the perisperm.

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Activity and Multiple Forms of Hydrolytic Enzymes in Germinating Sugar Beets (Beta vulgaris L.)

Cited by 3 publications

References 57 publications

Trennung und Visualisierung multipler Amylaseformen durch isoelektrische Fokussierung

Trennung und Visualisierung multipler Amylaseformen durch isoelektrische Fokussierung

Amylolytic activity in germinated Agrostemma githago L. seeds

Mobilisation of storage reserves during germination and early seedling growth of sugar beet

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