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 25°C, 2‐ to 5‐fold that in non‐transgenic rice. At 5°C, 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 5°C showed that transgenic rice displayed an increased capability to resist low temperature stress. The exposure of these plants to low temperature at 5°C for 8 days resulted in decreased catalase activities in leaves at 25°C, 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.