Abstract
A tracheary element (TE), a component of vessels, is a hollow dead cell differentiated through programmed cell death triggered by vacuole collapse. However, the mechanism of vacuole collapse during TE differentiation is unknown. In order to elucidate the molecular mechanism of the dynamics of tonoplast during that, we tried to find the Rab GTPase involved in TE differentiation as a factor regulated the dynamics of tonoplast. Genechip analysis and RT-PCR using in vitro TE differentiation system of Arabidopsis showed that the expression patterns of 9 Rab GTPase genes were changed during TE differentiation. Furthermore, a detailed analysis of the expression profiles of each Rab GTPase promoter::GUS gene in transgenic Arabidopsis was performed. At least 2 Rab GTPase genes (AtRab75 and At1g07410) were expressed in immature TEs, suggesting the relationship between Rab GTPase and TE differentiation. Now efforts are underway to investigate the expression profiles of other Rab GTPase genes.
