Journal of Tea Science

Identification of CAB Gene Family and Excavation of Key Genes Related to Leaf Yellowing Variationin Tea Plants (Camellia sinensis)

ZHONG Sitong, ZHANG Yazhen, YOU Xiaomei, CHEN Zhihui, KONG Xiangrui, LIN Zhenghe, WU Huini, JIN Shan, CHEN Changsong

Journal of Tea Science. 2024, 44(2): 175-192. doi:10.13305/j.cnki.jts.2024.02.007

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Members of the light-harvesting chlorophyll a/b binding protein (CAB) gene family play an important role in plant leaf yellowing variation. In this study, the CAB family members were identified from tea plant ‘Tieguanyin’ genomic data. The bioinformatics and expression patterns were analyzed. Furthermore, the expression patterns of the CABs gene were analyzed by gene cloning and qRT-PCR in tea cultivars with different leaf colors. The key CAB genes related to tea yellowing were screened by correlation analysis of leaf color parameters and chlorophyll SPAD values. The results show that 25 members of the CAB gene family were identified, their amino acid length ranged from 167-337 and the protein molecular weight ranged from 18.5-37.1 kDa. Most CAB members were stable and hydrophobic proteins, and distributed in chloroplast by the subcellular localization prediction. According to the evolutionary relationship, CAB family members are divided into 13 subfamilies, and the Lhcb1 subfamily has the most members. Cis-acting element analysis of promoter shows that CAB family members have a lot of light-responsive elements, as well as other elements related to growth and development, hormone response, and adversity stress. The members of Lhcb1 subfamily were cloned from tea plants, CAB1, CAB6, and CAB7 genes were screened by sequence alignment. The expression analysis shows that CAB1, CAB6, and CAB7 genes had tissue expression characteristics with higher expression levels in buds, leaves and fruits, and could respond to various stresses. Finally, the qRT-PCR indicates that the expressions of CAB1, CAB6, and CAB7 genes were consistent in the yellow and green leaves. Compared with green leaves, the expression of CAB genes in yellow leaves were significantly down-regulated. The correlation analysis of gene expressions and related leaf color parameters shows that the gene expressions of CAB1, CAB6, and CAB7 were significantly correlated with leaf color parameters a, b, L, and chlorophyll SPAD values (P<0.01). Among them, the expression of CAB1 shows the highest correlation coefficient. The subcellular localization analysis shows that CAB1 was distributed in the nucleus, cytoplasm, and chloroplasts. The studies analyzed the basic characteristics of CAB family members in tea plants and the key genes related to tea color variation were identified, which provided a theoretical basis for the molecular regulation mechanism of tea color variation.

Genetic Diversity and Population Structure Relationship Analysis of Wild Tea Germplasm Resources in Badong County, Hubei Province

CUI Qingmei, LIANG Jinbo, MA Huijie, HU Shuangling, CHEN Qinghua, WU Liyun, HE Mengdi, WANG Liubin, TAN Licai, ZHANG Qiang, WANG Liyuan

Journal of Tea Science. 2024, 44(2): 193-206. doi:10.13305/j.cnki.jts.2024.02.002

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Wild tea germplasm resources have high genetic diversity and are also a high-quality source for the breeding and utilization of local tea cultivars. In this study, 26 resources of wild tea plants from Badong County, Hubei Province, were collected and the genetic diversity and population structure of wild tea plants were analyzed using SSR molecular markers with the normal tea cultivars as the control. The results are as follows: (1) 16 pairs of primers detected an average of 5.12 alleles and 3.65 effective loci in the test materials. A total of 82 alleles were amplified, with each pair of primers amplifying a range of 3-8 labeled alleles. The average Shannon diversity index was 1.378. (2) Six core primer sites were selected from 16 pairs of primers, which can effectively detect and identify 26 materials in this study. (3) UPGMA evolutionary map of individual samples could divide all 48 materials into 7 categories. Wild tea plants and cultivated tea plants could be effectively divided through SSR detection. Population genetic structure analysis suggests that 26 wild tea samples could be divided into 2 subgroups. (4) Based on biochemical components, two samples with high EGCG content and two tea germplasms suitable for making black tea were selected. Results of this research show that diversity level of wild tea resources in Badong was high, with high genetic variation within the population. This study laid a foundation for further protection, development and utilization of wild tea germplasm resources in Badong.

The Development of CAPS Molecular Markers for CsAL1, A Gene Associated with Early and Late Spring Tip Emergence in Tea Plants

HUANG Mengdi, CHEN Lan, SU Qin, HU Jinyu, LIU Guizhi, TAN Yueping, LIU Shuoqian, TIAN Na

Journal of Tea Science. 2024, 44(2): 207-218. doi:10.13305/j.cnki.jts.2024.02.001

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Camellia sinensis is an economically important foliar plant. The time of spring sprouting is a crucial biological trait that affects the economic value of tea. Therefore, selecting and breeding early sprouting tea cultivars are of great practical significance for improving the quality and economic benefits of tea. The study used ‘Tieguanyin’ as the reference genome and screened a gene, CsAL1 (Auxilin-like 1, TGY040711), which was highly significantly correlated with the time of spring sprouting based on genome-wide association analysis. SNP calling was used to obtain SNPs of CsAL1 in each sample. Correlation analysis of the SNPs and spring sprouting phenotypes was performed to obtain the key SNP loci that associating with spring sprouting traits. Suitable enzyme cleavage sites were analyzed for each SNP to develop CAPS molecular markers related to early-sprouting traits in tea plants. PCR was used to amplify the CAPS molecular markers, which were then digested in the genomic DNA of 12 tea materials. The markers were further verified in 72 tea materials to provide a reference for the association between single-base mutations in CsAL1 and early sprouting traits using CAPS molecular markers. This study also provided theoretical support for the breeding of early sprouting tea cultivars.

Physiological Differences and Expression Analysis of Wax Synthesis Related Gene WSD1 in Tea Roots Treated with Fluorine

SONG Bo, JIA Peining, YE Wenqi, WU Jun, SUN Weijiang, XUE Zhihui

Journal of Tea Science. 2024, 44(2): 219-230. doi:10.13305/j.cnki.jts.2024.02.010

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Tea plant, as one of the plants with high fluorine contents, has fluoride-polymerizing property. In this paper, based on scanning electron microscopy, the roots of ‘Huangdan’ and ‘Foshou’ were treated with different fluoride concentrations (10 mg·L^-1 and 50 mg·L^-1) and different time periods (1 d and 16 d). The differentially expressed gene WSD1 of tea wax synthesis under fluoride treatment was screened from the transcriptome data of our research group. The results show that under 50 mg·L^-1fluoride treatment, the epidermal cells of ‘Huangdan’ root had slightly more wax on the surface and relatively loose cell arrangement, while the epidermal cells of ‘Foshou’ root had blurred boundaries, significantly more wax on the surface, and fluorine intolerance symptoms such as cell wall distortion and breakage. Quantitative fluorescence results of WSD1 related to wax synthesis show that WSD1 had a significant up-regulation effect on the wax content of tea root under exogenous fluoride treatment. The prediction results of WSD1 protein interaction network and correlation analysis show that WSD1 was negatively regulated by CSS0041298, CSS0012327 and CSS0049082. This study provided a theoretical reference for alleviating fluorine stress in tea plants from the perspective of the interaction between tea plants and wax synthesis, and provided a scientific basis for further exploring the regulation of fluorine absorption in tea plants and the breeding of fluorine-tolerant tea cultivars.

Seasonal Dynamic Characteristics of Soil Physical and Chemical Properties and Enzyme Activities of Different Planting Patterns in the Wuyishan

WANG Feng, CHANG Yunni, SUN Jun, WU Zhidan, CHEN Yuzhen, JIANG Fuying, YU Wenquan

Journal of Tea Science. 2024, 44(2): 231-245. doi:10.13305/j.cnki.jts.2024.02.004

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Tea (Camellia sinensis L.) is one of the most important and traditional economic crops widely cultivated in the subtropical regions of China, which are usually developed from forestland. Soil enzyme activity is an important indicator of soil fertility and nutrient transformation. The purpose of this study is to investigate the seasonal dynamic characteristics of soil properties and enzyme activities of different planting patterns in Wuyishan city, and to provide theoretical basis for reasonable evaluation of soil ecological effects of organic tea cultivation. In this paper, three different planting patterns (forestland, conventional and organic tea gardens) were selected as the research objects. Soil samples were collected in May, August, November and February from 2021 to 2022. The soil properties and enzyme activities (urease, nitrate reductase, polyphenol oxidase, catalase, invertase and acid phosphatase) were determined in different seasons, and the dynamic changes with seasons were also investigated. The results show that: comparing with the forestland, the contents of soil ammonium nitrogen, total phosphorus, available phosphorus and available potassium increased significantly in the conventional tea garden, while the total potassium and pH decreased significantly. Compared with the conventional tea garden, the soil organic matter and total nitrogen contents increased significantly in the organic tea garden. The soil total phosphorus, available phosphorus, total potassium and available potassium contents decreased significantly. The soil pH also increased, and the proportion of soil nutrients was more coordinated. The effects of planting pattern and season and their interactions on urease and peroxidase activities were significant. Compared with the forestland, the soil urease, polyphenol oxidase, catalase and acid phosphatase activities decreased by 12.05% to 63.55% in the conventional tea garden, while urease activities significantly increased by 324.95% in the organic tea garden, and the soil nitrate reductase activities were not changed by planting mode. In general, the soil urease, polyphenol oxidase, invertase and acid phosphatase activities were significantly higher in summer and autumn (May and August) than those in winter and spring (November and February). The highest soil nitrate reductase and catalase activities were found in spring (February). The results of permutational multivariate analysis of variance show that the effect of planting pattern on the overall soil physical and chemical properties was much greater than that of seasonal changes. Redundancy analysis shows that soil environmental factors explained 77.03% of the variation in soil enzyme activity, and the soil organic matter, total nitrogen, ammonium nitrogen, total phosphorus, soil available phosphorus, total potassium, available potassium and pH were the main driving factors of soil enzymes. In summary, the conversion of forestland into tea gardens has a significant impact on soil properties and enzyme activities. Conventional planting leads to the accumulation of available phosphorus and potassium in tea garden soil and the decrease of soil enzyme activity, while organic planting improves soil enzyme activity and enhances soil carbon and nitrogen nutrient supply capacity, and thus is beneficial for maintaining a sustainable ecosystem in tea garden soil.

Influence of Organic Planting on Soil Microbial Community Composition and Diversity in Tea Gardens

YAN Yuxiao, ZHOU Dapeng, YANG Yanfen, Xie Jin, LÜ Caiyou, YANG Guangrong, WEN Qinshu

Journal of Tea Science. 2024, 44(2): 246-260. doi:10.13305/j.cnki.jts.2024.02.003

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To reveal the influence of organic planting on the community composition and diversity of soil microbial community, 4 types of soils (ancient tea gardens, modern tea gardens, rubber fields, wastelands) were used as the research objects in 3 representative ancient tea mountains (Manzhuan, Yiwu and Youle) in Mengla County, Yunnan Province. The community composition of bacteria and fungi were identified using Illumina MiSeq PE300 high-throughput sequencing technology. The effects of organic planting and planting years on soil physical and chemical properties, microbial community composition characteristics and diversity were analyzed. The results show that organic planting could promote soil organic matter accumulation and increase the contents of nitrogen, phosphorus and potassium nutrients. The common number of bacteria OTUs in the soils of three tea gardens and non-tea gardens was 381. Among them, Yiwu Wasteland had highest number of unique OTUs (293), while the Rubber Land of Manzhuan had the lowest number of unique OTUs (28). The total number of fungi OTUs was only 24, with the highest number of fungi OTUs unique to Manzhuan ancient tea garden (337) and the lowest number of OTUs unique to Yiwu Modern Tea Garden (55). In addition, The Shannon diversity index of bacteria reached 5.88-6.62, which was significantly higher than that of fungi (2.71-4.30). The dominant bacteria and fungi in tea garden soils were basically similar to those in non-tea garden soil. However, there were significant differences in relative abundance among identified Acidimicrobiales, Bradyrhizobium, Varibacter, Xanthobacteraceae, Nitrospira, Bryobacter, Acidibacter and Planomyceteaceae among different tea mountains and land use modes. Compared with wasteland and rubber land, the relative abundance of Chaetomiaceae, Penicillium, Fusarium, Trichoderma, Mortierella, Agaricales and Eurotiomycetes in tea garden soil fungal communities were significantly higher than those in other soils. The abundance index of bacterial community Chao1 was significantly and positively correlated with soil TN and TP, and the bacterial community composition was more stable than the fungal community composition of the three mountains with ancient tea plants. Except for some tea garden soils, the abundance of soil bacteria increased with the increase of organic planting and planting years, while the abundance of fungi decreased and then increased with the beginning of organic planting. The diversity level of bacteria and fungi in modern and ancient tea gardens decreased with the increase of organic planting and planting years.

The Effect of Organic Management on Soil pH in Tea Gardens

SHEN Xingrong, WANG Qiuhong, HU Qiang, WANG Donghui, FU Shangwen, HAN Wenyan, LI Xin

Journal of Tea Science. 2024, 44(2): 261-268. doi:10.13305/j.cnki.jts.2024.02.011

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Soil excessive acidification is one of the main problems affecting the sustainable and healthy development of tea industry. To understand the long-term impact of organic management on soil pH of tea gardens, this study selected both soil samples from organic and conventional tea gardens in 84 tea producing counties of 18 provinces in China. The organic tea garden was managed organically from 1 to 21 years. The results show that the mean soil pH in organic tea gardens was significantly increased by 0.36, compared to the conventional tea gardens. With the increase of the years under organic management, the overall pH of tea garden soil shows a significant rise, and then a stable trend. The soil pH under organic management for 1-5, 6-10, 11-15 and 16-21 a significantly increased by 0.48, 0.23, 0.28 and 0.30, respectively compared to those in conventional tea gardens. The organic management also helped the soil pH towards the direction for most suitable growth and development of tea plants, the proportion of soils with pH 4.5-5.5 was only 41.9% in conventional tea gardens, it was increased to 53.1%、48.9%、58.7% and 66.7% in tea gardens under organic management for 1-5, 6-10, 11-15 and 16-21 a, respectively. These results indicate that organic management could not only overcome soil over acidification, but towards to the direction of the most suitable soil pH for the growth and development of tea plants.

Preparation of Torreya Seed Oil-EGCG Nanoemulsion and Its Effect on the Quality of Salad Dressing and Moon Cakes

WANG Yu'an, DU Wenkai, WAN Jinghong, XIE Dongchao, ZHANG Haihua, JIN Peng, DU Qizhen

Journal of Tea Science. 2024, 44(2): 269-282. doi:10.13305/j.cnki.jts.2024.02.013

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The composite nanoemulsion of torreya oil and epigallocatechin gallate (EGCG) was successfully prepared by ultrasonic emulsification method. The stability of the emulsion with different oil/water ratio and EGCG content was analyzed under different storage temperature and time, and the effect of the nanoemulsion on the quality of salad dressing and moon cake was further studied. The results show that the prepared torreya oil-EGCG nanoemulsion had stable properties (particle size=160-180 nm, PDI<0.2, Zeta potential≈﹣60 mV), and the oil/water ratio and EGCG had no significant effects on stability (P>0.05). Refrigeration and 2.0% EGCG nanoemulsion could reduce the loss of EGCG and inhibit its browning. The sensory quality of salad dressing with 1/10 torreya oil-EGCG nanoemulsion and 0.2% NHDC was improved. The antibacterial and antioxidant activity was significantly increased for prolonged quality stability. The addition of torreya oil-EGCG nanoemulsion can slow down the accumulation of acrylamide and reduce the loss of representative unsaturated fatty acids in moon cake baking. The above results indicate that nanoemulsion has great significance and prospects for development and use in improving food quality.

Identification of Antagonistic Streptomycetes Against Anthracnose Pathogen of Tea Plants and Determination of Their Inhibitory Properties

ZHANG Yudan, TAN Lin, LIU Zhonghua, XIAO Dungen, DENG Yulian, LI Guihua, HUANG Hong, YANG Xueyu, HU Qiulong

Journal of Tea Science. 2024, 44(2): 283-298. doi:10.13305/j.cnki.jts.2024.02.008

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Colletotrichum camelliae is an important pathogen causing anthracnose of tea plants. In order to obtain Streptomyces strains with better antagonistic effect on C. camelliae, the dilution coating method and plate standoff method were used to isolate and screen Streptomyces strains from the habitat of tea plantations. Morphological observation, physiological and biochemical characteristics and 16 S rRNA gene sequence analysis were combined to identify their species. Antimicrobial spectrum determination, mycelial growth inhibition test and spore germination inhibition test of C. camelliae were carried out for the isolated strains. The antifungal activities and stabilities of aseptic fermentation filtrate of the isolated strains against C. camelliae were determined by using the mycelial growth rate method. The extracellular enzyme-producing capacity, antimicrobial substance synthesis genes, volatile and non-volatile metabolite antifungal activity of the isolated strains were also determined. The results show that a strain XS-4 with better inhibitory effect on tea anthracnose pathogen was obtained and the plate inhibition effect on tea anthracnose pathogen was 76.42%. The strain XS-4 was identified as Streptomyces polychromogenes, which had good inhibitory effect on eight other plant pathogens and the antifungal properties have a broad spectrum. Scanning electron microscopy results show that the strain XS-4 could inhibit the growth of mycelium of tea anthracnose pathogen, and the mycelium was tightly entangled with each other and deformed. The spore germination inhibition test shows that the fermentation solution of strain XS-4 could inhibit the spore germination of C. camelliae, and the inhibition rate was 62.48%. The best fermentation medium for strain XS-4 was KMB medium, and the inhibitory active substance produced by 7 d incubation in KMB medium had the best inhibitory effect on tea anthracnose, the aseptic fermentation filtrate of strain XS-4 had a better stability to temperature, acid and alkali, ultraviolet, and protease. The non-volatile metabolites of strain XS-4 show better antifungal activity against tea anthracnose pathogen with aninhibition rate of 81.92%. The strain XS-4 has the ability to produce amylase, protease, β-1,3-glucanase, and cellulase. The pks-Ⅰ and pks-Ⅱ genes of strain XS-4 were associated with the production of antimicrobial substances. In conclusion, the strain XS-4 has a great potential for application in the biocontrol of anthracnose in tea plants.

Chemical Composition Analysis of Unique ‘Rattan Tea’ in Yunnan

FANG Chenggang, YANG Gaozhong, YANG Yingbiao, ZHANG Liqiu, CHEN Xia, LI Lianchao, LÜ Haipeng, LIN Zhi

Journal of Tea Science. 2024, 44(2): 299-315. doi:10.13305/j.cnki.jts.2024.02.009

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‘Rattan tea’ is a unique tea in Yunnan, named after the distinctive cultivation method developed by local tea farmers over generations which prompts tea tree trunks to resemble rattan in appearance. To investigate the impact of the ‘rattan tea’ pluck management system on tea quality, the one bud and two leaves from rattan tea plantation were collected to produce sun-dried tea, black tea and white tea, and the samples of the same kind of fresh leaves of the modern tea plantation were used as the control. These samples were used for the sensory evaluation and chemical composition analysis. The study shows that the sun-dried tea made from fresh rattan tea leaves exhibits a higher refreshing aroma and stronger taste, while the white tea has a stronger aroma and sweeter taste. In contrast, the black tea from modern tea gardens is characterized by a higher level of sweet aroma and a refreshing taste. The total catechin content in rattan tea was significantly lower than that in modern tea plantations, particularly in rattan white tea (67.11 mg·g^-1), which was significantly lower than that of modern tea plantation white tea (84.19 mg·g^-1). The content of theanine in rattan sun-dried tea (16.79 mg·g^-1) was significantly higher than that in modern tea plantation sun-dried tea (14.69 mg·g^-1). Both rattan sun-dried tea and rattan white tea exhibited lower phenol-to-amino acid ratios. A total of 205 primary metabolites were identified, with rattan white tea accumulated a richer profile of sugars. In addition, a total of 127 volatile compounds were detected in all tea samples. Alcohols and esters were the predominant volatile components in different tea types, with rattan white tea exhibiting significantly higher total volatile compound content than modern tea plantation white tea. Rattan black tea contained a higher content of geraniol, while modern tea plantation black tea had higher levels of linalool. In summary, the processing methods of sun-dried tea and white tea were found to be more conducive to obtain high-quality rattan tea products, and the overall chemical quality of tea samples made from rattan tea plantation were better than that of tea samples from modern tea plantation.

Analysis of Flavor Characteristics and Biochemical Composition Differences of Ziyang Green Tea Based on Sensory Evaluation and Metabolomics Techniques

CHEN Dequan, REN Yangmei, HE Mengdi, LI Youxue, YE Lili, XUE Huaqian, ZENG Jianming, DING Changqing

Journal of Tea Science. 2024, 44(2): 316-328. doi:10.13305/j.cnki.jts.2024.02.005

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To analyze the differences in flavor characteristics and biochemical composition of Ziyang green tea with different drying processes, 6 Xixiangtea (hot-air convection drying combined with roller-type conduction drying) and 10 Cuifeng tea (hot-air convection drying) were used for the study, and their flavor profiles and biochemical composition were analyzed by sensory evaluation, component detection,UHPLC-Q-Exactive/TM and multivariate statistical methods. Sensory analysis shows that the aroma of Xixiang tea was mainly high-fresh, and the Cuifeng tea was mainly faint-scent. The color of Xixiang tea was darker green than that of Cuifeng tea. The overall sensory score of Cuifeng tea was higher than that of Xixiang tea. The quantitative analysis shows that the total amino acids and 10 amino acid fractions (histidine, arginine and threonine,…) were significantly higher in Xixiang tea than those in Cuifeng tea (P<0.05), but the contents of tea polyphenols, catechin fractions and caffeine, and other quality components, did not show significant differences. A total of 262 non-volatile compounds were identified by metabolomics analysis, including 13 classes of amino acids, catechins, dimeric catechins, phenolic acids, flavonoid glycosides and organic acids. Partial least squares discrimination and comparative analysis found that there was no difference in metabolite species between Xixiang tea and Cuifeng tea, but there was a difference in their contents. Compounds with VIP>1.2 were selected as key differential compounds, mainly amino acids, phenolic acids and flavonoid glycosides. The contents of amino acids and flavonoi dglycosides in Cuifeng tea were lower than those in Xixiang tea, while the content of dimerized catechins was higher than that of Xixiang tea. This study provided a theoretical basis for a comprehensive understanding of the formation of the quality of Xixiang tea and Cuifeng tea, as well as a reference for the sensory quality of dry tea and biochemical compositional differences due to different drying processes of green tea.

Mechanism of Dark Tea Water Extract in Regulating Autophagy in Non-Alcoholic Fatty Liver via the AMPK/mTOR Signaling Pathway

LI Linli, XIA Xuting, SHI Min, GE Jun, MAO Caiwei, YU Changhong, LIU Fulin

Journal of Tea Science. 2024, 44(2): 329-340. doi:10.13305/j.cnki.jts.2024.02.012

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This study aimed to investigate the intricate mechanisms underlying the modulatory effects of Anhua dark tea on autophagy to ameliorate steatosis induced by a high-fat and high-sucrose diet (HFHS) in mice with non-alcoholic fatty liver disease (NAFLD). Male C57BL/6J mice were divided into different groups, including a normal group, a model group, a Western medicine group (10 mg·kg^-1), and various doses of dark tea groups (0.75, 1.5, 3.0 g·kg^-1). The therapeutic regimen was administered concurrently with the modeling process for a duration of 10 weeks using the HFHS-induced NAFLD model. At the end of the experiment, liver indices, blood lipids, liver function, liver pathology indicators, autophagy markers, and expression levels of key genes in the autophagy-related signaling pathway were assessed. Comparative analyses with the normal group revealed significant increases in liver index and levels of serum cholesterol (CHO), triglycerides (TG), low-density lipoprotein cholesterol (LDL-C), aspartate aminotransferase (AST), and alanine aminotransferase (ALT), as well as a substantial reduction in high-density lipoprotein cholesterol (HDL-C) levels in the model group. The liver of the mice exhibits signs of steatosis, characterized by an abundance of lipid droplets of different sizes. Protein expression analysis reveals a marked decrease in the levels of microtubule-associated protein light-chain-3B (LC3B), Bcl-2-interacting coiled-coil protein 1 (Beclin1), and phosphorylated adenosine monophosphate-activated protein kinase/adenosine monophosphate-activated protein kinase (p-AMPK/AMPK). Conversely, there was a significant increase in the levels of sequestosome-1 (p62) and phosphorylated mammalian target of rapamycin/mammalian target of rapamycin (p-mTOR/mTOR). Compared to the model group, gavage with dark tea decreased the liver index, serum levels of CHO, TG, LDL-C, AST, ALT, p62, and p-mTOR/mTOR in NAFLD mice, and increased serum HDL-C, along with LC3B, Beclin1, and p-AMPK/AMPK protein levels. The improvements were confirmed by tissue staining results and observations using transmission electron microscopy. In summary, our findings suggest that dark tea, by activating the AMPK/mTOR signaling pathway, may regulate autophagy, thereby alleviating hepatic steatosis and improving non-alcoholic fatty liver disease (NAFLD).

Research on the Inhibition of Tea Extracts and Different Types of Tea on Mycobacterium tuberculosis

XU Jing, HUANG Youyi, HUANG Jin, LI Chunlei

Journal of Tea Science. 2024, 44(2): 341-349. doi:10.13305/j.cnki.jts.2024.02.006

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This study was aimed at investigating the inhibitory effect of tea on Mycobacterium tuberculosis strain H₃₇Ra by using the Oxford cup method for the bacteriostatic assay of H₃₇Ra. The inhibitory abilities of different tea extracts (tea polyphenols, tea polysaccharides and tea saponins) and different teas (Huanong Lvzhen, Dazongchaoqing, Guangdong Dayeqing, Fuding Shoumei, Tieguanyin, Fenghuang Dancong, Keemun black tea, Xiaguan Tuocha and Green brick tea) on the activity of H₃₇Ra strain were studied. The results of the bacteriostatic experiments of tea extracts show that tea polyphenols exhibited significant bacteriostatic ability against H₃₇Ra strain and the bacteriostatic effect was gradually enhanced with the increase of tea polyphenol concentration. At a concentration of 40 mg·mL^-1, tea polyphenols show long-term inhibition of the growth of H₃₇Ra strain. Tea polysaccharides and saponins had no inhibitory effect on Mycobacterium tuberculosis. Different types of tea exhibit varying degrees of antibacterial ability, among which, the ethyl acetate fraction of Fenghuang Dancong had a stronger bacterial inhibition ability than other isolates. The column chromatography separated by 60% ethanol had the strongest bacterial inhibition ability, suggesting that tea polyphenols were the main components to inhibit the growth of H₃₇Ra strain. The results confirm that tea has an inhibitory effect on H₃₇Ra strain and different tea extracts and different tea types have different antibacterial abilities, which provides a new idea for the development of tuberculosis related antibacterial drugs.

Effect of Jinhua White Tea on Weight Loss of High Fat Diet Mice

LIU Zhenyun, KE Wanping, ZHOU Xirui, LI Menghua, BO Jiahui, YE Xingmei, LIU Zhonghua, XIAO Lizheng, LIN Yong

Journal of Tea Science. 2024, 44(2): 350-362. doi:10.13305/j.cnki.jts.2024.02.014

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The aim of this study was to investigate the effect of Jinhua white tea (JWT) on weight loss of high fat diet mice. In this study, JWT was selected as the material and compared with the white tea without fungal fermentation method. The determination of major chemical components in the tea was conducted. An obesity mouse model was established, and the mice were administered orally with 400 mg·kg^-1 of JWT water extract as an intervention. The body weight of the mice was regularly recorded, and obesity-related indicators were measured, followed by histopathological analysis of the tissues. The results indicate that after fungal fermentation, the contents of flavonoids and theabrownin increased significantly, while the contents of tea polyphenols, free amino acids, soluble sugars, theaflavins and thearubigins decreased significantly. Meanwhile, among the catechin components, only epicatechin content increased significantly. JWT effectively inhibited the body weight gain in high fat diet mice, reduced their liver and white adipose tissue indices, alleviated inflammation and oxidative stress, and protected the structural integrity and function of the liver and intestines. Compared to white tea without fungal fermentation method, JWT significantly reduced the levels of TC, TG and inflammatory factors in mice, which were speculated to be related to the mass reproduction of Eurotium cristatum and the increase of flavonoids, epicatechin, theabrownin and other substances. While white tea shows a more pronounced effect on relieving liver oxidative stress, which was speculated to be due to the significant decrease in the content of epigallocatechin gallate after fungal fermentation. These findings suggest that JWT has a significant weight loss effect on mice with diet-induced obesity, while fungal fermentation method can improve the lipid-lowering and weight-reducing effects of white tea to a certain extent.

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