Effects of Exogenous Soybean Isoflavones on Physiological Parameters of Achyranthes bidentata Blume Seedlings under UV-B Radiation Stress

In this study, effects of soy isoflavones (SIF) on the growth and development, physiology, content of medicinal ingredients and expression levels of enzyme-encoding genes in Achyranthes bidentata Blume under UV-B radiation were systematically investigated. The results showed that UV-B radiation adversely affected the growth and development of A. bidentata seedlings, causing ROS accumulation and the anti-oxidation system to be damaged. However, 1 mg/L exogenous SIF treatment conferred enhanced tolerance under UV-B radiation stress in A. bidentata seedlings by decreasing the concentration of MDA, H2O2, and modulating SOD and POD activities. Furthermore, 1 mg/L SIF reduced the content of oleanolic acid and ecdysterone in leaves and increased the content of oleanolic acid in roots, but had no significant effect on the content of ecdysterone in roots under UV-B radiation stress. SIF had a different degree of influence on the expression levels of antioxidant enzyme genes as well as medicinal ingredients enzyme-encoding genes in A. bidentata. The results showed that 1 mg/L exogenous SIF treatment had a positive effect on the growth, development and physiology in A. bidentata seedlings under UV-B radiation stress. To our knowledge, for the first time we are reporting that the use of 1 mg/L exogenous SIF enhances A. bidentata seedlings tolerance to UV-B radiation stress.