Gibberellins and carbohydrate mobilization in germinating barley grains

non-dormant buds (Tuan & Bonner, 1964). This observation has been interpreted to imply that there is a massive repression of the genome in dormant tissue. If this hypothesis is valid, then the role of hormones in regulating dormancy may involve the repression and de-repression of DNA. Thus it is possible that the occurrence of high concentrations of abscisic acid and low concentrations of gibberellins during the later stages of seed development may lead to repression of the genome, and that once the dormant state has been induced the maintenance of high concentrations of abscisic acid may not be necessary. Some evidence has, indeed, been obtained that abscisic acid affects the activity of chromatin isolated from radish hypocotyls (Pearson & Wareing, 1969). On the other hand, Ihle & Dure (1970) have suggested that in developing cotton seeds abscisic acid acts by preventing the premature translation of long-lived RNA.