In this study,we investigated the functions of 2-alkenal reductase(AER)in improving drought tolerance.Transgenic tobacco plants overexpressing 2-alkenal reductase and wild-type tobacco plants(SR)were used to measure the biomass,photosynthetic rate,chlorophyll fluorescence parameters,contents of chlorophyll,MDA and H₂O₂ under drought stress and rehydration.Results showed that:(1)the biomass,content of chlorophyll,photosynthetic rate,chlorophyll fluorescence parameters and the capability for scavenging H₂O₂ of the transgenic tobacco plants were significantly higher than those of control plants under drought treatment.(2)After rehydration,the physiological indexes of tobacco recovered.The recovery capability of transgenic lines is better than that of wild-type.These results indicated that overexpression of AER gene lead to enhanced drought tolerance in transgenic tobacco plants.