SUCROSE AND RAFFINOSE UTILIZATION DURING THE EARLY STAGES OF BARLEY GERMINATION

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Abstract
Investigations of sucrose and raffinose metabolism revealed that in the ungerminated grain sucrose occurs in greater quantities than raffinose in both the embryo axis and the scutellum. The sucrose content of the axis and scutellum declines sharply over the germination phase but increases sharply at post-germination (i.e., root emergence) as hexose sugars from the modifying endosperm pass into the scutellum. As development of the seedling progresses, sucrose is rapidly transported from the scutellum to the growing axis where the young roots, with an active invertase system, utilize sucrose during growth. Raffinose content of the embryo declines slowly and there is no accumulation of this oligosaccharide after germination. Chromatographic studies suggest that in the embryo raffinose may undergo degradation to galactose and sucrose, the galactose moiety being enzymically epimerized to glucose before entering the general metabolic pool of sugars.