[SO2-caused oxidative stress and modulation of some signal molecules in wheat]

By adding different concentration SO2 to culture boxes, this paper studied the responses of wheat seedling's superoxide anion radical O2*- and antioxidant enzymes to SO2. The results showed that when the concentration of SO2 was 10 and 40 microl x L(-1), the O2*- content and peroxidase (POD) and catalase(CAT) activities of wheat leaf were increased, while the activity of superoxide dismutase(SOD) was reduced. When the SO2 concentration was 50 microl x L(-1), the activities of POD and CAT were decreased, with the top end leaves appeared necrosis, and more fungi multiplied on green leaves. Presoaking wheat seeds with 1 mmol x L(-1) salicylic acid (SA) for 6 h or with 10 mmol x L(-1) H2O2 for 12 h could efficiently alleviate the oxidative stress caused by SO2, with the O2*- content decreased and the activities of test antioxidant enzymes increased. Under SO2 fumigation, ethylene significantly inhibited the activities of test enzymes, and promoted the O2*- production rate. When applying SA and ethylene at the same time, SA could almost completely eliminate the influences of ethylene on O2*- production and test enzyme activities.