Abstract
Rice endosperm tissues have storage proteins, which are accumulated in two types of protein bodies (PBs). Prolamin is deposited in PB-I, glutelin and globulin are stored in PB-II. To clarify the transport pathway for storage proteins, we studied the electron microscopic analysis of rice developing endosperm tissues.
We found novel vesicles derived from rough endoplasmic reticulum (rER). The structures of novel vesicles were different from that of the ER-derived PB- I and the Golgi-derived dense vesicles. They had an electron-dense core of PB-II type storage proteins surrounded by an electron translucent layer. Immunocytochemical analysis revealed that the novel vesicles had glutelin and globulin in the electro dense core. In addition, BiP, an ER-resident molecular chaperone, was localized in the novel vesicles, but also in PB-II. These results suggest that the novel vesicles mediate transport of glutelin and globulin directly from the ER to PB-II in rice endosperm.
