Search for mutants that have defects in "bulbs", complex structures on the vacuolar membrane, to reveal its molecular basis and function

Abstract

The plant vacuole has many functions and is essential for growth and development. We previously identified "bulb", as a complex and mobile structure on continuous vacuolar membrane (Saito et al. 2002). We have carried out genetical approaches to obtaining its molecular basis and function. We found that zig/atvti11, sgr2, sgr3, 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. In contrast, bulbs were still observed in autophagy mutants (atg2, atg5), indicating that autophagy is not a main pathway for the biogenesis of bulbs. Now we also have started forward-genetical approach to find mutants, which show defects in bulb or vacuolar morphology. Progress of the screening and the analysis of candidate line will be reported.