On Starch Statolith in the Lamina Joint of Rice Plants

Abstract

The starch grains were localized in the lamina joint of the second etiolated leaves of rice plants, and an inversive and horizontal displacement of the leaves caused a sedimentation of the starch grains across the cell. Therefore, it is probable that the starch grains behave as statolith in the gravity perception mechanism of geonastic growth movement of the lamina joint. However, the sedimentation time less than about 2 hours in this experiment was much shorter than 6 to 17 hours, the presentation time reported in Maeda's previous paper. It is important to study why the latter is so long. An electron microscopical study showed the presence of etioplasts in lamina cells, amyloplasts in lamina joint cells and etioplasts containing starch grains in leaf sheath cells. The observation also implies the necessity for an attention to small size organella, e.g. mitochondria etc., for an analysis of the discrepancy between the sedimentation time and the presentation time.