Effects Of Fluoride On The Enzyme Of Polyphenol Metabolism In Tea Seedlings

Tea plant (Camellia sinensis L.) which has a good ability of accumulating fluorine, can absorb and concentrate a large number of fluorine from the environment, and the concentration of fluorine from tea can be 10-100 times larger than the other plants. However, researches on the effects of fluorine on the quality of tea and its physiology are still limited. In this experiment Chinese varieties Fudingdabai, Wuniuzao and Fuyunliuhao which were grown hydroponically for 30 days, were used to study on the effects of different concentrations of fluorine on the main ingredients of tea, polyphenols and the impacts of fluorine on polyphenol metabolic enzymes. The results of this study were as follows:Under the same concentration fluoride stress, the accumulation ability of Fluoride among different varieties was significant different, the content of Fluoride in different varieties showed:Wuniuzao> Fudingdabai> Fuyunliuhao. Also, the content of Fluoride in fresh leaves was close related to the leaves’position. The content of Fluoride in mature leaves was significantly higher than young leaves.With concentration of fluoride increased, the content of polyphenols and catechins first increased then decreased. And the lower concentrations (2 mg/L-4 mg/L) promote the generation of polyphenols and catechins while the higher concentrations (8 mg/L-16 mg/L) suppress it. The results showed that the impact of fluoride on tea quality was associated with the concentration of fluoride treatments. The low concentration was beneficial for the quality of tea but the high concentration was harmful for the tea quality. The reason why the content of tea polyphenol was decreased is that high fluoride concentrations may cause combined effects of inhibition of photosynthesis, respiration, glucose metabolism.Fluoride had a significant influence on the activity of catechins synthase PAL, C4H, CHI, PPO, DFR, LCR, ANR, and had no significant influence on the 4CL. Under fluoride stress, the activity of PAL and C4H in tea was in a similar tendency like a synergy effect.The correlation analysis of the three varieties which didn’t apply the fluoride between anthocyanin content and PAL activity was conducted. It showed that it was extremely significant linear positive correlation between anthocyanin content and PAL activity, and the correlation was reduced after the fluoride added. These results indicated that PAL activity is related to accumulation of anthocyanin, but may not be the only key enzymes.The expression of catechins biosynthetic enzyme gene PAL, DFR, LCR has almost the same variation trend under the Fluoride treatment, first increased and then decreased. The maximum expression of enzyme gene between varieties corresponding to fluoride concentration was different. The polyphenol content and total expression of DFR and LCR were related to the activity of PAL, C4H, DFR/LCR, PPO, the correlation coefficient r>0.5; Catechin monomer, total catechins had a low correlation coefficient with expression quantity of PAL, DFR and the LCR, but they all showed a trend of the rise first then reduce. The above results show that:the accumulation of catechins maybe related to the expression of PAL, DFR, LCR, but they were not a simple linear relationship. This phenomenon may be caused by the mutual adjustment of a variety of intermediate metabolites and the together working of the variety of enzymes and auxiliary factors which still need further study.