Abstract
The plant vacuole has many functions and is essential for growth and development. The vacuolar membrane has quite complex architecture and dynamic features. We previously identified "bulb", as a complex and mobile structure on continuous vacuolar membrane (Saito et al. 2002). To reveal its biological function, we have carried out several approaches to obtaining "further structural evidence", "more direct proof for qualitative difference as a sub-region-like character" and "its function". We obtained a transgenic Arabidopsis line, which visualizes bulbs even in imbibed seeds or the floral organ. In this line, bulbs are observed in a variety of tissues than we already reported. We also found that zig/atvti11 and sgr2-1, which are known to have defects in shoot gravitropism and morphology of the vacuolar membrane in the endodermal cell in flowering stem, are virtually devoid of bulbs. Now we are trying to analyze its ultrastructure by high-pressure freezing and electron microscopy.
