Rape embryogenesis VI. Formation of protein bodies

The storage protein synthesis starts in Brassica napus var. Górczański embryo at the final embryogenesis stage, i.e. in green seeds. Storage protein accumulate in selected zones adjacent to big vacuoles. These vacuoles, as well as surrounding protein zones, are subject to fragmentation. Young aleuron grains originate. They grow occupying sites of declining vacuoles. In mature rape embryo two kinds of protein bodies occur: aleuron grains, well-stainable with protein-specific dyes, and myrosin grains weakly-stainable with them but PAS-positive. Myrosin grains occur earlier than aleuron grains in special cortex and cytoledon cells. Although the first aleuron grains form in outer cells of lateral cap parts and in cortex cells at the hypocotyl-root boundary, they originate most rapidly in endodermis. In the embryo axis aleuron grains form so rapidly that at the beginning of browning of the seed coat most of them are already formed. Aleuron grains developed in all embryo cells accept in those of the youngest columella layers and differentiated procambial strands. The accumulation of storage protein lasts till the end of seed maturation