Abstract
Root system is responsible for acquisition of water from the soil. It is important for plants to avoid drought stress by controlling the orientation of root growth. Hydrotropism is the directed growth of roots in response to moisture gradients, but its mechanism remains to be clarified. We therefore isolated Arabidopsis mutants whose roots are impaired in hydrotropic response and named them mizu-kussei (miz). Here, we identified the mutated gene responsible for its phenotype by map-based cloning. MIZ1 was expressed in the columella cells of the root cap, suggesting that it could function in a perception or signaling pathway of hydrotropism. Interestingly, MIZ1 contained a domain conserved only in terrestrial plants. Thus, MIZ1 is probably a gene that played a role in adaptation of plants to terrestrial environment. This work was supported by the Program for Promotion of Basic Research Activities for Innovative Biosciences.
