Physiological Effects of Gibberellic Acid. VII. Electron Microscopy of Barley Aleurone Cells

Abstract

The ultrastructure of the cytoplasm of the cells of isolated barley aleurone tissue was investigated by electron microscopy in an initial attempt to relate gibberellin-induced changes in enzyme spectrum and activity with morphological and cytological manifestations of hormone action. Characteristic cell structures include aleurone grains, limited by a unit membrane, which contain 2 typesof spherical inclusions. Sphaerosomes surround the aleurone grains and are ranged along the plasma membrane. Plastids, mitochondria, endoplasmic reticulum, and Golgi structures are also present. The changes in aleurone tissue incubated in gibberellic acid are compared with those of water controls. Gibberellic acid-treated aleurone diverges from the relatively static controls in enlargement, fusion, and vacuolization of the aleurone grains, disappearance of globoids within the aleurone grains, almost complete disappearance of the sphaerosomes and extensive erosion of the cell walls.