Effects of Ozone Stress on Secondary Metabolism and Antioxidant Capacity in Soybean Roots

Abstract

In this paper, to examine the effects of elevated ozone on secondary metabolism and antioxidant capacity in soybean roots, as well as reactive oxygen species and antioxidant enzymes activity. Soybean grown in open top chambers (OTCs) were exposed to ambient air ((O 3)=40nmolmol -1 ) and elevated ozone ((O3)=110±10nmolmol -1 ). The results revealed that with ozone concentration rising, compared with control, the O3 stress induced the total flavonoids content in soybean root of all treatments showed a significant rising trend (P<0.05), and the total polyphenols content showed a rising trend but not significant. The PAL and PPO activity of soybean root was always lower than that of CK, the LOX activity of soybean root was always higher than that of CK, but the PALˎLOX and PPO activity of soybean root expressed an increased trend with the increase of soybean growth period. However, variation of antioxidant enzymes activity in soybean roots was very different from each other. Superoxide dismutase (SOD) activity was lower than the CK treatment at flowering and podding stages under elevated ozone stress, it presents a volatility changes. During the whole growth stage, elevated ozone stress induced a decrease on activity of catalase (CAT) except for flowering stage, it had a significant increase (p<0.05), the ozone treatment was higher than the CK treatment in general except flowering stage. Activity of peroxidase (POD) was increased under elevated ozone. It had a higher representation (p<0.05) than the CK treatment at every stage. It can be concluded that the ozone stress has significant effects on soybean roots, and effects on soybean roots' normal growth.