The Development of Protein Bodies in the Storage Tissues1

Homogenates of the developing endosperms of maize, wheat, andbarley and of developing cotyledons of peas have been separatedon sucrose density gradients. Protein bodies have been recognizedby their content of storage proteins, their density, and theirappearance under the electron microscope. The distribution ofthe endoplasmic reticulum was followed by measuring NADH-cytochromec reductase. Glutamate dehydrogenase, catalase, and triose phosphatedehydrogenase—respectively marker enzymes for mitochondria,microbodies, and plastids—were also present in the gradients.Differences were found between the different species with respectto the association between the endoplasmic reticulum and thestorage proteins. There was no evidence for any vacuolar markerenzymes associated with the cereal protein bodies. The proteinbodies of wheat and barley appear to be similar to each otherbut differ from maize in that the latter have much more endoplasmicreticulum associated with them. In contrast the protein bodiesof peas co-sediment with vacuolar marker enzymes.