Ultrastructure of Endosperm Protein Bodies in Developing Rice Grains Differing in Protein Content

Ultrastructural aspects of the development of protein bodies (aleurone grains) in endosperm of grains of two rices differing in protein content are described. Formation of rough endoplasmic reticulum complexes prior to protein deposition was observed only in the higher protein grain. From 8 days after flowering three types of protein body were observed, one of which was restricted to the peripheral endosperm (sub-aleurone) layers. The higher protein grain had a greater number of protein bodies and rough endoplasmic reticulum in the endosperm cells than the lower protein grain. Increase in total protein with maturity was the result of increased number of protein bodies rather than increase in size; the protein bodies were concentrated in the peripheral endosperm layers.