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| Mechanism of Cr（Ⅵ） Uptake by Hyperaccumulator Leersia hexandra Swartz |
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| KeyWord:L. hexandra; Cr（Ⅵ）; uptake; metabolic inhibitors; SO2-4 |
| Author Name | Affiliation | | LU Yuan-yuan | Guangxi Scientific Experiment Center of Mining, Metallurgy and Environment, Guilin University of Technology, Guilin 541004, China | | ZHANG Xue-hong | Guangxi Scientific Experiment Center of Mining, Metallurgy and Environment, Guilin University of Technology, Guilin 541004, China | | LIU Jie | Guangxi Scientific Experiment Center of Mining, Metallurgy and Environment, Guilin University of Technology, Guilin 541004, China | | WU Chan-cui | Guangxi Scientific Experiment Center of Mining, Metallurgy and Environment, Guilin University of Technology, Guilin 541004, China |
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| Abstract: |
| Leersia hexandra Swartz, present in Southern China, has been found to be a chromium hyperaccumulator. Under hydroponic conditions, the mechanisms of Cr（Ⅵ） uptake by roots of L. hexandra were studied at 30 μmol Cr（Ⅵ）·L-1. Absorption of Cr（Ⅵ） by the plant was significantly reduced by uncoupler 2, 4-dinitrophenol（DNP）, ATPase inhibitor（Na3VO4） and low temperature（2 ℃）, with the greatest inhibition（69.8% reduction） by low temperature, implying that Cr（Ⅵ） uptake by roots of L. hexandra was an active process associated with energy metabolism. In addition, Cr（Ⅵ） absorption followed Michaelis-Menten kinetics and was competitively inhibited by sulfate. Sulfate（SO2-4） did not affect the maximum absorption rate of Cr（Ⅵ）（0.143~0.148 μmol·g-1 DW·h-1）, but increased the constant Km values by 27.6% compared with the control（the plants grown in 25% Hoagland solution）. However, sulfate-deficiency decreased the Km by 24.3%. This result suggested that the Cr（Ⅵ） uptake by the roots of L. hexandra may be partially carried via sulfate transporters. |
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