Abstract
Rice is the most Al tolerant species among small-grain cereal crops, but neither the mechanisms nor the genes responsible for the high Al tolerance are understood. We previously cloned an Al-tolerant gene (Als1) using an Al-hypersensitive mutant. When this gene was introduced into the mutant, the Al tolerance was recovered. This gene was mainly expressed in the roots and the expression was up-regulated by a short exposure (2 h) to Al. In a transgenic rice carrying Als1 fused with GFP under the control of Als1 promoter, the signal was observed in the plasma membrane of all cells at the root tips. Immunostaining also showed that Als1 is located in all cells of the root tips. Furthermore, Al was detected in the cytoplasm of all root cells of the mutant but not in the wild-type rice. These results suggest that Als1 is involved in the exclusion of Al from the cells.
