Effects Of Glutamate And GABA On The Physiology And Biochemistry Of Tea Plants And Study Of The Mechanism

Tea as one of the most widely consumed non-alcoholic beverages in the world,it’s an important domestic consumption and export agricultural product in our country.As a four-carbon,non-protein amino acid,γ-aminobutyric acid（GABA）is involved in p H regulation,signal transduction,response to stress,regulation of carbon/nitrogen metabolism,promotion of plant growth,and enhancement of plant photosynthesis.As the precursor of GABA synthesis,L-glutamate is one of the important amino acids in organisms.At present,there is little research on whether spraying L-glutamate can increase the GABA content in tea plants and promote the effect of tea yield and quality.Therefore,this article uses L-glutamate as an exogenous inducing factor to explore whether its exogenous treat can promote the enrichment of GABA and improve the quality of tea,and explore its application as an amino acid fertilizer in agricultural production.In order to study the effects of exogenous L-glutamate on the yield and quality of tea,we designed different concentrations of GABA and L-glutamate to be sprayed on the surface of tea plants,and measured the photosynthetic parameters and ChlorophyⅡcontent of tea leaves after 1,3 and 10 days;determine the moderate concentration of exogenous GABA and L-glutamate solutions to treat tea plants,and explore the effects of L-glutamate on the photosynthesis and quality of tea plants from the chlorophyⅡfluorescence characteristics of tea leaves and the changes of the main contents of tea;Exogenous spraying of glutamate,analysis the expression of GABA shunt,chlorophyⅡsynthesis,photosynthetic-related gene in tea leaves,verify whether L-glutamate can affect GABA shunt,chlorophyⅡsynthesis,CO₂assimilation at the transcription level,and clarify L-glutamate effects on the physiology and biochemistry of tea plants;also studied the effects of different anaerobic methods on the L-glutamate synthesis and accumulation of GABA in fresh tea leaves,the changes in amino acid components in the anaerobic enrichment of tea leaves,and the GAD activity of fresh tea leaves of different varieties,to explore the suitable products of GABA tea,and then spray L-glutamate through exogenous sources to determine its effect on GABA enrichment in tea.The main results are as follows.（1）Exogenous L-glutamate and GABA significantly increased the photosynthetic parameters Pn,Ci Tr,and the contents of chlorophyⅡa and chlorophyⅡb of tea plants,decreased the Gs,of which 500 mg·L^-1 of exogenous glutamate,5 m M exogenous GABA has a better effect in this research.（2）Exogenous L-glutamate and GABA can increase the utilization of light energy of tea plants and thus increase the yield of tea:significantly increase the fluorescence transient OJIP of tea tree chlorophyll a,and promote the reduction rate of QA in the reaction center of PSⅡin tea leaves.The photosynthetic electron transfer.Glutamic acid and GABA can improve the quality characteristics of tea leaves:on the tenth day,the tea water extract increased by20.6%and 14.7%,and the free amino acid content increased by 17.9%and 20.2%,respectively..In addition,exogenous GABA significantly increased the caffeine content,GC,EC,and EGCG content in tea.L-glutamate treatment increased the EC and EGCG content,while the tea polyphenols didn’t change significantly.（3）The best method for anaerobic enrichment of GABA in tea is determined:3 h anaerobic/2 h aerobic/3 h anaerobic.‘shuchazao’and‘sucha120’have strong GAD activity,high endogenous L-glutamate content,and L-glutamate in the GABA tea have not decrease a lot after enrichment so that the quality of GABA tea is guaranteed.It reveals these two varieties have good potential to be prepared into GABA tea.In the process of anaerobic enrichment,GAD is activated to catalyze L-glutamate to synthesize GABA,and cause the increase of Ala and Asp;exogenous L-glutamate increases the endogenous glutamate content of tea plants,but it is annoying for fresh tea leaves.The content of amino acid components did not change significantly after oxygen.（4）Exogenous L-glutamate can enhance the expression of GABA shunt genes Cs GAD1and Cs GABA-T at the transcriptional level,and enhance the expression of important enzyme genes Cs HEMB-1,Cs CHLM,Cs Chl G,Cs CAO,Cs Por B,Cs HEMA1 in the chlorophyⅡsynthesis pathway,Up-regulate the Rubisco enzyme gene and the activating enzyme genes Csrca and Csrbc S to enhance the carbon assimilation process of photosynthesis...