The Ability of Wheat Aleurone Tissue to Participate in Endosperm Mobilization

Abstract

A distinctive property of the seed is that throughout its life a major part of metabolism is concerned, in one way or another, with the food reserves. During development of the seed, a high proportion of its increasing mass is storage material laid down by the activity of the multitude of enzymes which convert sucrose, amides and amino acids into starch, protein and triacylglycerols, in various proportions according to the species. This synthesis of reserves which dominates metabolism during development is not found again during the life of the seed, at least under normal circumstances. It is replaced, in the period following germination, by the transformation of reserves into sucrose, amino acids and amides, which move into the axis to support its growth, i.e. replaced by processes which in overall terms are the exact reverse of what happens in development. The seed thus displays a sharp temporal separation of metabolic processes involving these reserves—there is synthesis, and little or no breakdown as the seed develops; and mobilization, with virtually no synthesis, after the seed has germinated.