Abstract
We showed that changes in the glutathione redox state are required for the transdifferentiation of mesophyll cells into tracheary elements (TEs) in the Zinnia experimental system. To verify significance of the cellular redox regulation by glutathione in planta, we generated transgenic plants with altered glutathione redox ratio by introducing a chimeric gene construct where a gene for dehydroascorbate reductase (DHAR), or chloroplastic or cytosolic glutathione reductase (GR) was fused to the CaMV35S promoter. DHAR oxidizes GSH and GR regenerates GSH from GSSG. All transgenic plants generated showed retarded root formation, compared to non-transgenic plants. Conforcal laser scanning microscopy showed that those transgenics had the reduced number of cells in the root meristematic region. Taken together, changes in the glutathione redox state regulate the rate of root elongation by modulating the rate of cell division. We are also investigating on TE differentiation occurring in the vicinity of the root meristematic region.
