Effects of Pb stress on antioxidase system and growth of Rabdosia Rubescentis Folium / 中草药

ABSTRACT

Objective: To study the effect of different concentration of plumbum (Pb) stress on antioxidase activity in different organs of Rabdosia Rubescentis Folium (RRF, the aerial parts of Rabdosia rubescens) and their growth, and provide the basis for the growth regulation of R. rubescens under Pb pollution. Methods: Ramets hydroponic test was performed with the concentration of Pb (0, 135, 270, and 540 mg/L) and the stress time (50 d), taking superoxide dismutase (SOD), peroxidase (POD), catalase (CAT), relative growth rate (RGR), biomass, and Pb mass fraction as indexes, the determination of antioxidant enzyme activity was performed with spectrophotometer, and plant's Pb mass fraction of plant with plasma emission spectrometer was carried out. Results: Under Pb stress at different concentration (135-540 mg/L), SOD activity in the leaves and the roots of R. rubescens was increased first and then decreased, but no significant difference on SOD activity in the leaves at each level; POD activity in the leaves under Pb concentration (135-270 mg/L) was no significant difference compared with the control group, but was significantly increased at the concentration of 540 mg/L, while the POD activity in the roots under Pb stress at various concentration was significantly lower than that of the control group which gradually went up after declined; CAT activity in the leaves increased significantly with Pb concentration rising, and the activity in the root decreased gradually with Pb concentration rising. No significant effect on the growth of R. rubescens at low and mid levels of Pb concentration (135 and 270 mg/L), but under high concentration (540 mg/L) of Pb treatment compared with the control group, the biomass and RGR decreased by 33.33% and 46.59%, respectively. Conclusion: The stimulus response is different obviously for antioxidase activities between the leaves and roots of R. rubescens; Through fitting model predictive analysis, the critical Pb concentration is 301.99 mg/L, which decreases RGR by 10% compared with control group (P < 0.01). RRF shows a strong resistance to Pb stress.