Screening Of Tea Germplasm Resources With High EGCG Content, High Theanine Content And High Caffeine Content

Tea germplasm resources of Camellia sinensis(L.)O.Kuntze have very important value,which is the material basis of production and utilization,variety innovation and modern tea seed industry development.Epigallocatechin-3-gallate(EGCG)and theanine are important quality components and main active components of tea.However,there are few studies on screening high EGCG and high theanine tea varieties.In this study,the catechin composition,theanine and amino acid contents of 113 tea varieties were determined,and the tea resources with high EGCG and high theanine were screened out,so as to provide material basis for the breeding of new excellent tea varieties.The main research results are as follows :1.The total catechin content of 113 tea cultivars ranged from 6.30% to 14.85%,including 8 high total catechin tea cultivars(total catechin content>14%),5 high EGCG tea cultivars(EGCG>7%),1 high Epicatechin-3-gallate(ECG)tea cultivar(ECG>3%)and 2 high Epigallocatechin(EGC)tea cultivars(EGC>3%).The content of EGCG was between 2.36% and 8.16%,and the highest content was more than three times that of the lowest content.There was a significant difference in EGCG content among 113 tea cultivars.The contents of EGCG,ECG,Epicatechin(EC)and catechin(C)in tea in summer were higher than those in spring,while EGC and Gallocatechin-3-gallate(GCG)in tea in summer were lower than those in spring.The catechin quality index ranged from 141.55 to 954.14,mainly distributed in 200-400.There were 8 tea varieties with catechin quality index higher than 700.The correlation analysis showed that EGCG and ECG contents were significantly positively correlated with the total amount of ester-type catechins,the total amount of catechins and the quality index of catechins,while EGC and EC contents were significantly positively correlated with the total amount of simple catechins and negatively correlated with the quality index of catechins.2.The contents of free amino acids and theanine were significantly different among different tea cultivars.The content of free amino acids ranged from 0.585 % to 5.160 %,and theanine content ranged from 0.316 % to 2.987 %.Four high amino acid tea resources(amino acids>4%)and eight high theanine tea resources(theanine>2%)were screened.The ratio of theanine and amino acid content ranged from 42.37% to 79.18%,and concentrated in 50%-60%.The correlation coefficient between theanine and amino acid content was 0.963,showing a very significant positive correlation.The contents of free amino acids in tea showed a certain seasonal variation.The contents of theanine and amino acids in spring were higher than those in summer,and the ratio of theanine content and total amino acids in spring was higher than that in summer.3.Caffeine content > Theobromine content > Theophylline content in 113 tea varieties,of which caffeine content ranged from 2.11% to 4.64%,and the ratio of caffeine to total alkaloids ranged from 63% to 97%.There were great differences in caffeine content among different varieties.Eight high caffeine tea varieties were screened out(caffeine>4%).The change trend of caffeine content was not obvious in spring and summer.