Light Microscopy of Cell Organelles in the Scutellum of Rice during Germination

Abstract

Rice seeds, before and during germination, were fixed and embedded in glycol methacrylate or epoxy resin. Semithin sections (0.5 or 2 μm in thickness) were prepared and examined by light microscope after staining by several schedules. 1. Aleurone grains, lipid grains and starch grains were observed in scutellar parenchyma cells by the following histochemical procedures: PAS for starch grains, sudan black B for lipid grains, fast green for matrix protein of aleurone grains and toluidine blue for globoid inclusions. 2. Cytological changes in the scutellum and the endosperm during the first 5 days of germination were described. Aleurone grains in the scutellum enlarged and the matrix protein within them commenced to be hydrolysed 6 hr after soaking. The residual vacuoles, resulted from the hydrolysis, underwent extensive coalescence 36-48 hr after soaking. Small starch grains in the scutellar cells were observed 6 hr after soaking and disappeared during 12-24 hr. At 30 hr after soaking starch grains again appearcd in the cells and they increased in number after 36 hr and then they grew in size. Starch grains in the endosperm commenced to be digested in 1-2 cell layers near the epitherial cells of scutellum after 36 hr. These results suggest that the reappeared starch grains in the scutellum are derived from starch which was accumulated in the endosperm.