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| Apparent characteristics of active transmembrane uptake of fluoride by tea plant roots |
| Received:January 20, 2016 |
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| KeyWord:tea plant;fluoride;low temperature;metabolic inhibitor;active uptake |
| Author Name | Affiliation | E-mail | | WANG Yu-mei | School of Resources and Environment, Anhui Agricultural University, Hefei 230036, China | | | CHAI Ru-shan | School of Resources and Environment, Anhui Agricultural University, Hefei 230036, China | | | GAO Hong-jian | School of Resources and Environment, Anhui Agricultural University, Hefei 230036, China | hjgao@ahau.edu.cn |
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| Abstract: |
| Active fluoride(F) uptake by tea plant roots determines the accumulation of fluoride in tea leaves. Here a solution culture experiment was conducted to examine the characteristics of active transmembrane uptake kinetics of fluoride by tea plant roots through plasma membrane and to investigate the influences of low temperature, metabolic inhibitors and chloride on fluoride absorption. Results indicated that concentration-dependent F uptake in tea plant roots was characterized by a saturation curve that was fitted by the Michaelis-Menten model. The Vmax and Km values were 13.9 μg·h-1·g-1 root dry weight and 0.59 mmol·L-1, respectively. Compared with 25℃, F accumulation in tea plant roots was decreased by 49.8% at 4℃. Metabolic inhibitors, such as 2,4-DNP, NaN3, and Na3VO4, significantly decreased the concentrations and content of F in tea plant roots in a concentration-effect manner. The amount of F in tea plant roots reduced by 16.1%, 39.1% and 20.6% by 2 mmol·L-1 2,4-DNP, 0.2 mmol·L-1 NaN3 and 0.6 mmol·L-1 Na3VO4, respectively. At 5 mmol·L-1, chloride also significantly inhibited F absorption in tea plant roots, with 73.1% of inhibition. In summary, the uptake of F by tea plant roots is an active process that is related to the electrochemical potential gradient across the plasma membrane, metabolizable energy and carrier proteins. |
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