Abstract:Sulfur dioxide (SO2) content in the air is tending higher with the industrial development. Sulfur dioxide pollution causes environment deterioration and acid rain, which bring about severe harmfulness to plant growth and development. Catalase (CAT) plays an important role in keeping the balance of active oxygen metabolism in plant cell. However, the effects of SO2 on CAT activity in crops including maize (Zea mays L.) are rarely reported. The present study was conducted to provide primary result in the area with 5 maize hybrids of Ludan 981, Lainong14, DH3, Suyu 9, and Yedan 2. In a simple self-made obturator (168 cm×65 cm×63 cm), maize seedling was treated with 60 mg m-3 SO2 for 2 h. The CAT activity of treated leaf was measured at 0, 6, 12, 24, 48, and 72 h after treatment, respectively. The CAT isoenzymes and CAT gene were analyzed by PAGE and RT-PCR, respectively. The results showed that the CAT activity of leaf response to SO2 differed significantly (P<0.01) among maize cultivars. The CAT activity reduced by 59% and 38% in the sensitive hybrid Ludan 981 and non-sensitive hybrid Yedan 2 respectively as compared with control (no SO2 treatment). The CAT activity rose gradually after SO2 treatment and restored to the normal level at 48 h after treatment. The analyses of isoenzymes and RT-PCR also received the same results, indicating that CAT might play an important role in the interaction of SO2 and maize.