The Development of Protein Bodies in the Storage Tissues1

Abstract

Homogenates of the developing endosperms of maize, wheat, and barley and of developing cotyledons of peas have been separated on sucrose density gradients. Protein bodies have been recognized by their content of storage proteins, their density, and their appearance under the electron microscope. The distribution of the endoplasmic reticulum was followed by measuring NADH-cytochrome c reductase. Glutamate dehydrogenase, catalase, and triose phosphate dehydrogenase—respectively marker enzymes for mitochondria, microbodies, and plastids—were also present in the gradients. Differences were found between the different species with respect to the association between the endoplasmic reticulum and the storage proteins. There was no evidence for any vacuolar marker enzymes associated with the cereal protein bodies. The protein bodies of wheat and barley appear to be similar to each other but differ from maize in that the latter have much more endoplasmic reticulum associated with them. In contrast the protein bodies of peas co-sediment with vacuolar marker enzymes.