Abstract:The changes of the protective system against activated oxygen during the enhancement of the chilling resistance induced by the cold hardening and ABA treatment in rice seedlings were studied. The results indicated that in the treated seedlings, activities of SOD and GR of the chloroplast as well as the antioxidant AsA and GSH contents of the leaves increased while the electrolyte leakage decreased. Therefore, its chilling resistance Was enhanced.By using isoelectrofocusing gel electrophoresis analysis, the intensity of three isozyme bands of SOD and the isozyme bands 1, 2, 3 and 6 of GR, except 4, 5, were increased to a different degree in two treated seedlings.After chilling stress, all the activities of SOD, GR and the contens of AsA, GSH were decreased in the treated and untreated seedlings, but the reduction of two enzyme activities and the antioxidant contents in the treated seedlings were less than those of the untreated seedlings.The increase of SOD and GR activities induced by cold hardening and ABA treatment were inhibited by cycloheximide (CHM), at the same time the electrolyte leakage was increased. These results showed that there was a close correlation between the enhacement of chilling resistance and the increase of the protective system ability in the rice seedlings and that the effects of cold hardening and ABA treatment on the Protective system against activated oxygen in rice seedlings were similar.
