Abstract
Roots show hydrotropism in response to gradient in moisture or water potential. We recently isolated ahydrotropic mutant of Arabidopsis, miz1 and identified the gene responsible for its phenotype. miz1 roots display not only ahydrotropic growth but also a reduced phototropism. To explore the regulatory mechanism related to these phenotypes, we examined whether MIZ1 transcription and MIZ1 protein localization are modulated by moisture gradient or light stimulation. MIZ1 transcription was observed at root cap and vascular bundle, when seedlings were grown under continuous light. Under the same conditions, MIZ1 protein was localized not only at root cap and vascular bundle but also at cortial cells where MIZ1 gene was not expressed. While these expression patterns were unchanged upon hydrostimulation, MIZ1 expression diminished only at the root cap cells when seedlings were grown in the dark. These results suggest that MIZ1 at the root cap regulate cross-talking of hydrostimulation and light stimulation.
