Gibberellic acid and the fine structure of barley aleurone cells : II. Changes during the synthesis and secretion of α-amylase.

This paper describes the ultrastructural changes in barley aleurone cells following exposure to gibberollic acid (GA3) for 10-12 hr and longer. These changes involve a further proliferation of the endoplasmic reticulum (ER), distention of the endoplasmic reticulum (ER) cisternae (12-16 hr of GA3) and proliferation of vesicles from the ER and dictyosomes (14-22 hr). Accompanying these changes is a reduction in the size of the aleurone grains and a decrease in the number of spherosomes. Plastids and microbodies however appear to increase in number during this period of GA3 treatment. The relevance of these ultrastructural changes to GA3-stimulated synthesis of hydrolases is discussed.