Variation in Antioxidant Enzyme Activities of Two Strawberry Cultivars with Short-term Low Temperature Stress

Changes of superoxide(O ) and hydrogen peroxide(H O ), malondialdehyde(MDA) contents and 2 2 2 activities of enzymes involving cell defense in leaves of strawberry (Fragaria×ananassa Duch) plantlets under different time of low temperature stress were studied. With the increase of stress times, the rates of O2 generation and contents of H O increased to a certain degree and then decreased. The MDA contents and the 2 2 relative conductivity fluctuated were increased during the treatment. The activities of antioxidant enzymes, such as superoxide dismutase(SOD), catalase(CAT), peroxidase(POD) and ascorbate peroxidase(APX) were gradually increased to a certain degree and then decreased. The results clearly suggested that low temperature stress triggered an increase of reactive oxygen species (ROS) and the early accumulation of ROS in plants might lead to the production of antioxidant defense system. If the stress were too strong, the defense system of plants could not remove the more production of ROS effectively and result in severely damage to plants or even death.