Ectopic Expression of Enhances Salt Stress Tolerance in Rice.

Salt stress can severely reduce crop yields. To understand how rice () plants respond to this environmental challenge, we investigated the genes involved in conferring salt tolerance by screening T-DNA tagging lines and identified (alt olerance ctivation -ominant). In that line, expression of was enhanced by approximately eightfold when compared with the non-transformed wild type (WT). This gene was highly expressed in the callus, roots, and panicles. To confirm its role in stress tolerance, we generated transgenic rice that over-expresses under a maize promoter. The Ox plants were salt-tolerant at the vegetative stage, based on our calculations of chlorophyll fluorescence (Fv/Fm), fresh and dry weights, chlorophyll concentrations, and survival rates. Under normal paddy field conditions, the Ox plants were somewhat shorter than the WT control but had improved agronomic traits such as higher total grain yield. They were also more tolerant to osmotic stress and hypersensitive to abscisic acid. Based on all of these results, we suggest that has important roles in determining yields as well as in conferring tolerance to salt stresses.