Aleurone (from Greek "aleuron", flour) is a
proteinfound in protein granules of maturing seeds and tubers. The term is also used for the outermost cell layer of the seed coat, the aleurone layer.
Aleurones can have two different morphological features, homogenous and heterogeneous. The homogenous aleurone consists of similar protein bodies (e.g. "
Phaseolus vulgaris") while the heterogeneous aleurone consists of granules of different shapes and types of proteins covered with a membrane (e.g. " Ricinus communis").
The aleurone layer surrounds the
endospermtissue of grass seeds. In the cultivated cereals it is usually single-layered (except in barley). In cereals with starchy endosperm, the aleurone contains about 30% of the kernel's proteins. In multicolored corn, anthocyaninpigments in the aleurone layer give the kernels a dark, bluish-black color.
germination, the plant embryoproduces the hormone gibberellinthat triggers the aleurone cells to release enzymes for the hydrolysisof starch and storage proteins into the endosperm. The breakdown of the starchy endosperm supplies sugars to drive the growth of roots and the acrospire. This effect is inhibited by the plant hormone abscisic acid, which keeps the seed dormant.
The gibberellin effect on the aleurone is used in
brewing, specifically in the production of barley maltwhere treatment ensures that a batch of barley seeds will germinate evenly.
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