Pedosphere 26(5): 709--716, 2016
ISSN 1002-0160/CN 32-1315/P
©2016 Soil Science Society of China
Published by Elsevier B.V. and Science Press
| Responses of carbonic anhydrase to cadmium in the zinc/cadmium hyperaccumulator Picris divaricata Vant. |
LIU Sai-Hua1,2,3, TANG Ye-Tao1 , QIU Rong-Liang1,3, YING Rong-Rong4, GE Rui-Guang5 and JI Xiong-Hui2 |
1School of Environmental Science and Engineering, Sun Yat-sen University, Guangzhou 510275(China)
2Hunan Soil and Fertilizer Institute, Changsha 410125 (China)
3Guangdong Provincial Key Lab of Environmental Pollution Control and Remediation Technology, Guangzhou 510275 (China)
4
Nanjing Institute of Environmental Sciences, Ministry of Environmental Protection, Nanjing 210042 (China)
5Key Laboratory of Gene Engineering of the Ministry of Education and State Key Laboratory of Biocontrol, College of Life Science, Sun Yat-sen University, Guangzhou 510275 (China) |
| ABSTRACT |
| A number of higher plants are able to hyperaccumulate cadmium (Cd). However, it is unknown whether Cd plays a biological functional role in the carbonic anhydrase (CA) of hyperaccumulators. A hydroponic experiment was conducted to explore the potentially physiological function of Cd in CA and the accumulation and tolerance of Cd in the Zn/Cd hyperaccumulator Picris divaricata Vant. P. divaricata was exposed to nutrient solutions with six Cd concentrations (0, 5, 10, 25, 50 and 75 μmol L-1). After 12 d, plants were harvested for the analysis of plant biomass, Cd concentration and CA activity. The Cd concentrations in plant increased with the increasing Cd in nutrient solution, reaching 640 and 3 100 mg kg-1 in shoot and root, respectively, at the 75 μmol L-1 Cd treatment. Meanwhile, plant growth was enhanced by the Cd treatments at 5--25 μmol L-1, but it was significantly inhibited when the plants were exposed to solutions with higher Cd concerntrations (50 and 75 μmol L-1). Exposure to Cd significantly increased the CA activity in P. divaricata, which reached a maximum value of 21.27 U mg-1 proteins at the 25 μmol L-1 Cd treatment, and the CA activity and shoot Cd concentration were positively correlated at solutions of Cd ≤ 25 μmol L-1. Moreover, two protein bands appeared on the denatured gel electrophoresis of purified CA, indicating that P. divaricata may have CA isomers with their respective molecular weights at around 60 and 55 kDa, at least one of which is Cd-bound. In addition, trace amounts of Cd in purified CA significantly increased with the supplied Cd concentration in nutrient solution (5--25 μmol L-1). The results suggested that Cd may play a biological role by enhancing the activities and forming the active Cd-specific CA in the hyperaccumulator P. divaricata. |
| Key Words: Cd, enzyme purification, heavy metal, metal-contaminated soil, phytoremediation, plant enzyme, protein |
| Citation: Liu, S. H., Tang, Y. T., Qiu, R. L., Ying, R. R., Ge, R. G. and Ji, X. H. 2016. Responses of carbonic anhydrase to cadmium in the zinc/cadmium hyperaccumulator Picris divaricata Vant.. Pedosphere. 26(5): 709-716. |
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