Wheat catalase expressed in transgenic rice can improve tolerance against low temperature stress

We examined whether the expression of wheat catalase (EC 1.11.1.6) cDNA in transgenic rice (Oryza sativa L.) could enhance tolerance against low temperature injury. Transgenic rice plants expressing wheat CAT protein showed an increase of activities in leaves at 25degreesC, 2- to 5-fold that in non-transgenic rice. At 5degreesC, catalase activities were about 4-15 times higher than those in non-transgenic rice were. A comparison of damage observed in leaves as they withered due to chilling at 5degreesC showed that transgenic rice displayed an increased capability to resist low temperature stress. The exposure of these plants to low temperature at 5degreesC for 8 days resulted in decreased catalase activities in leaves at 25degreesC, but the transgenic plants indicated 4 times higher residual catalase activities than those of non-transgenic ones. The concentration of H-2 O-2 in leaves was kept lower in transgenic rice than that of the control plants during the 8 days chilling. These results suggest that the improved tolerance against low temperature stress in genetically engineered rice plants be attributed to the effective detoxification of H-2 O-2 by the enhanced catalase activities.