Effect of sulfur dioxide on ROS production, gene expression and antioxidant enzyme activity in Arabidopsis plants

摘要

Sulfur dioxide (SO _2) is one of the most common and harmful air pollutants. To analyze antioxidant response of plants to SO _2 stress, we investigated the reactive oxygen species (ROS) levels, transcript alterations and antioxidant enzyme activities in Arabidopsis thaliana (Col-0) exposed to 0, 2.5, 10 and 30 mg m ~(-3) of SO _2. The results showed that both superoxide radical (O2-{dot operator}) generation rate and hydrogen peroxide (H _2O _2) content increased in SO _2-treated Arabidopsis shoots. GeneChip and RT-PCR analysis revealed that transcript levels of peroxidase (POD), glutathione peroxidase (GPX) and superoxide dismutase (SOD) genes enhanced after exposure to 30 mg m ~(-3) SO _2 for 72 h. The content of glutathione and activities of SOD, POD and GPX increased significantly during 72 h of SO _2 exposure. However, catalases (CAT) activity changed slightly under SO _2 stress. Furthermore, the results of in-gel enzyme assays indicated that SOD (FeSOD and Cu/ZnSOD) and POD isoforms increased after exposure to SO _2 for 72 h, whereas two CAT isoforms (CAT2 and CAT3) declined. Malondialdehyde content kept at a low level within 72 h of SO _2 exposure, but increased significantly after exposure to 30 mg m ~(-3) SO _2 for 120 h along with decrease in the level of ROS and activities of SOD and GPX. Our results indicated that increased ROS may act as a signal to induce defense response to SO _2 stress. Antioxidant status plays an important role in plant protection against SO _2-caused oxidative stress, though the defense capacity cannot sufficiently alleviate oxidative damage occurring under prolonged exposure to higher concentrations of SO _2.