The Formation of Endoplasmic Reticulum in the Aleurone Cells of Germinating Wheat: an Ultrastructural Study

In the aleurone cells of the quiescent wheat grain endoplasmic reticulum was sparse and present as short profiles. During germination long profiles of endoplasmic reticulum developed near to the nuclear membrane and in close association with plastids. Much of this development occurred during the first 2 d of germination, but further development and stacking of the membranes appeared to take place after this time. The development of the long profiles was independent of the presence of the embryo and therefore of control by gibberellic acid. On the contrary, after the second day of germination gibberellic acid produced a decline in the amount of endoplasmic reticulum associated with vesiculation of the reticulum profiles. The results of this ultrastructural study are discussed in the context of available information on the bio synthesis of phospholipids in aleurone tissue. Some aspects of our results are at variance with those of others who have studied the aleurone tissue of barley. These differences are discussed and suggestions for their resolution are made.