Journal of Tea Science

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Analysis on the Competitiveness and Complementarity of Tea Trade between China and RCEP Members

LI Zheng, LIU Ding, HUO Zenghui, CHEN Fuqiao

Journal of Tea Science 2022, 42 (5): 740-752. DOI: 10.13305/j.cnki.jts.2022.05.010

Abstract （787）

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The signing of RCEP had facilitated intra-regional trade liberalization. It is of great practical significance to investigate the impact of RCEP on China's tea import and export trade. Based on the tea trade data of China and other RCEP members from 2011 to 2020, combining the analysis of the current situation of intra-regional import and export trade, this study calculated several indicators such as revealed comparative advantage index (RCA), export similarity index (ESI), trade complementarity index (TCI), trade intensity index (TI) and intra-industry trade index (GL) to measure the competitiveness and complementarity of bilateral tea trade. The results indicate that the tea export competitions between China, Vietnam and Indonesia were more prominent. China's tea export had long-term comparative advantages, and the comparative advantages of green tea export were obvious, while the comparative advantages of China's export of large packaged black tea lag behind Indonesia and Vietnam. China's tea export was highly similar to Japan, Thailand, Singapore and South Korea, and had strong competitiveness in export structure. In addition, the tea trade between China and New Zealand, Brunei, Australia was highly complementary. China's tea trade with Indonesia, New Zealand and Vietnam was mainly intra-industry trade in some years, while with Australia and Myanmar was mainly inter-industry trade. Finally, under the framework of RCEP agreement, strategies including expanding potential markets, dealing with technical barriers to trade and optimizing export structure were proposed.

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The Effect of Red Light Withering on the Volatile Components of Tea Leaves and the Quality of Black Tea Product

LIN Jiazheng, TU Zheng, CHEN Lin, YE Yang, LIU Fei, WANG Yuwan, YANG Yunfei, WU Xun, LYU Haowei

Journal of Tea Science 2021, 41 (3): 393-405. DOI: 10.13305/j.cnki.jts.2021.03.006

Abstract （782）

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Red light withering contributes to the formation of tea aroma. However, the effect of different red light quality on the volatile components of withered tea and the quality of the black tea product after processing remains to be studied. In this study, headspace solid phase micro extraction-gas chromatography-mass spectrometry was used to detect and analyze the volatile components of withered leaves under different light treatments such as dark, red light (630 nm, 1 000 lx, 3 000 lx), natural light (260-325 lx), and the dynamic changes of the volatile components of withered leaves and red light withered differential volatile substances under different light treatments were studied. The results show that a total of 130 volatile components were detected in withered leaves at different time periods, including 26 alcohols, 33 esters, 29 hydrocarbons, 12 aldehydes, 13 ketones, and 17 others. Comparing different light withering methods, it was found that the total content of volatile components in the red light 3 000 lx group pre-mid withering period (The first 8 h) were significantly higher than that in other groups. With the increase of red light intensity, the total content of esters increased significantly (P<0.05), while the total content of ketones decreased significantly (P<0.05). Through orthogonal partial least squares discriminant analysis, the variable projection importance factor was greater than 1 and the coefficient of variation was greater than 50%, 5 volatile components were screened out with the greater response to red light, including 1,2-dimethylpropyl-2-methyl-butanoic acid ester, 1-isocyano-3-methyl-benzene, decanal, 2-methyl-2-decanol, linoleic acid ethyl ester. Among them, the coefficient of variation of decanal was as high as 133.34% under red light 1 000 lx. The results of this study could provide a scientific basis for the improvement of black tea aroma quality and targeted regulation.

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Analysis of the Metabolism of Amino Acids during the Withering of White Tea

CHEN Jiajia, ZHU Chensong, ZHU Wenwei, SHANG Hu, LIN Lin, LUO Yuqin, SUN Weijiang

Journal of Tea Science 2021, 41 (4): 471-481. DOI: 10.13305/j.cnki.jts.2021.04.003

Abstract （733）

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In order to investigate amino acids during the withering of white tea, metabolomics and proteomics were used to detect amino acids and related enzymes in the withered leaves at 0 h, 12 h and 30 h. The results show that the total amino acids had no significant change during withering process. While serine, leucine, phenylalanine, lysine, tyrosine, histidine, isoleucine, proline, valine, phenylalanine and γ-aminobutyric acid contents increased but N-acetyl-L-glutamic acid, reduced glutathione, N-α-acetyl-L-arginine decreased in the early stage of withering (0-12 h). The contents of glutamic acid and acetylglycine decreased in the later stage. Proteins tended to degrade during the withering process and the enzymes enriched in amino acid synthesis pathway were down-regulated in the early stage of withering, and the enzymes related to degradation were up-regulated in the later stage. The protein amino acids were mainly derived from protein hydrolysis, and then converted into non-protein amino acids. The γ-aminobutyric acid was regulated by glutamate decarboxylase under dehydration conditions. The increase of its content promoted the umami taste of white tea.

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Identification and Transcriptional Regulation of CLH Gene Family and Expression Analysis in Albino Tea Plants (Camellia sinensis)

WANG Tao, WANG Yiqing, QI Siyu, ZHOU Zhe, CHEN Zhidan, SUN Weijiang

Journal of Tea Science 2022, 42 (3): 331-346. DOI: 10.13305/j.cnki.jts.2022.03.003

Abstract （638）

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Chlorophyllase (CLH) is the key enzyme in the degradation of chlorophyll, stripping its phytol to form dephytolithochlorophyll a. The full-length cDNA sequences of three CsCLHs genes were obtained from the second leaves of albino tea cultivar ‘Baijiguan', and bioinformatics analysis was performed. The results show that the three CsCLH genes could be divided into two subfamilies. The full length of CsCLHs was 894-975 bp, encoding 297-324 amino acids. The protein molecular weights were 31.99-34.91 kDa. The isoelectric points were 4.89-7.61, and the instability coefficients were 38.94-48.24. CsCLH1.1 and CsCLH1.2 were unstable proteins, while CsCLH2 was a stable protein. The subcellular localization prediction results of Cell Ploc show that three CsCLH proteins were located in chloroplast, while the results of Wolf Psort show that CsCLH1.1 and CsCLH1.2 were located in cytoplasm and CsCLH2 was located in chloroplast. The qRT-PCR results on the ‘Baijiguan' leaves indicated that expressions of CsCLHs were inhibited by shading treatment and light induced CsCLHs' expressions. Expression pattern analysis of CsCLHs shows that CsCLH1s were highly expressed in the albino cultivars. In addition, it was identified that CsCDF5 could bind to the CsCLH1.1 and CsCLH2 promoters according to the yeast one hybrid system. In conclusion, CsCLHs in albino tea leaves might be involved in chlorophyll degradation and play an important role in the process of albino leaf, which provided a reference for further investigation in the function of the CLH gene family and the albinism of leaves in tea plants.

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Analysis of Metabolite Changes in the Natural Withering Process of Fu′an White Tea Based on Non-targeted Metabolomics Approach

YUE Wenjie, JIN Xinyi, CHEN Mingjie, YE Naixing, GUO Li, ZHAO Feng

Journal of Tea Science 2021, 41 (3): 379-392. DOI: 10.13305/j.cnki.jts.20210304.001

Abstract （635）

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In this study, Camellia sinensis cv Fu'an Dabai was used as materials to make white tea following the standard indoor natural withering procedure. Samples were collected every 3 h, and non-targeted metabolomics was used to analyze tea metabolite changes. Principal component analysis (PCA) shows that metabolite contents in fresh leaves showed regular dynamic changes during the process of indoor natural withering of white tea. Totally 109 metabolites with significant difference were identified and showed 5 major patterns. These patterns could be divided into four stages: 24 h before withering, 24-48 h during withering, 48-57 h during withering and after 57 h. According to their structure, these metabolites can be classified into 4 types. The 8 monomer catechins (Catechins) showed a downward trend during the withering process. The contents of 18 proanthocyanidins (PAs) and 5 Theasinensins (TSs) showed different trends. The galloyl containing PAs and TSs showed an upward trend, while non- galloyl containing PAs and TSs showed an opposite trend. For glycoside derivatives, 6 kaempferol glycosides, 4 Quercetin (quercetin) glycoside and 1 apigenin glycoside showed an upward trend. Their contents increased significantly after 48 h withering. In the process of withering, 5 of the 12 phenolic acids showed an upward trend. While the rest 7 showed a downward trend. All of them reached their peaks or bottom at 57-60 h. In addition, 22 different metabolites including alkaloids, amino acids, peptides, coumarins, sugars, etc. were also identified. Caffeine showed an upward trend. Their contents reached the peaks at 60 h. Theobromine decreased significantly in the mid-withering period, and slightly recovered in the latter period. The contents of 2 theanine isomer and 4 coumarins rose to the peak at 12 h. After that, there was an overall downward trend during the withering process. These data offered important insights for understanding the biosynthesis and regulation mechanism of white tea during indoor natural withering process.

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Detection of Bitterness-related Substances in Youxi Bitter Tea and Correlation Analysis with Bitterness

WEI Shasha, PENG Jing, CHEN Zhidan, SUN Weijiang, LIN Lin

Journal of Tea Science 2021, 41 (3): 337-349. DOI: 10.13305/j.cnki.jts.2021.03.003

Abstract （615）

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The main taste substances of 37 individuals from four regions of natural distribution of Youxi bitter tea were detected and their bitterness were also evaluated. The main evaluation group members were evaluated and screened according to the ranking method test and quantitative description ability test in food sensory analysis, and 7 panelists with high accuracy and good repeatability were obtained finally. The results of taste substances detection show that the biochemical components and bitter taste of Youxi bitter tea were diverse. The individuals of Chimu village were more bitter than the other three regions, and the contents of gallic acid, EGCG, ECG and theobromine were higher. The bitterness intensity of individuals in Guangming Village was the lowest with high content of non-gallated catechins such as EGC and EC and caffeine. The contents of lysine, cysteine and total amino acids of individuals in Qiushan village were higher. The contents of umami amino acids (aspartic acid and serine) and bitter amino acids (histidine and methionine) in non-protected areas of Chimu village were higher. The correlation analysis between bitterness intensity and the contents of taste substances shows that the contents of theobromine and valine were positively correlated with bitterness intensity, and the content of aspartic acid with sweet taste was significantly and negatively correlated with bitterness intensity.

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Nomenclature, Typification, and Natural Distribution of Camellia sinensis var. assamica (Theaceae)

ZHAO Dongwei

Journal of Tea Science 2022, 42 (4): 491-499. DOI: 10.13305/j.cnki.jts.2022.04.007

Abstract （610）

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Camellia sinensis var. assamica (Theaceae) is a globally cultivated plant for beverages. The efforts to clarify its nomenclature and type are reviewed here. Griffith proposed Camellia sect. Thea (L.) Griff. as a name at new rank rather than a new taxon in 1854 based on Art. 41.4 of the Shenzhen Code. Camellia sealyana T.L. Ming is excluded from sect. Thea because of its abaxially punctate leaves and free styles. Masters did not validly publish Thea assamica in 1844, but this Latin name was validated in 1847 by Hooker. Steenis first proposed the new combination, Camellia sinensis (L.) Kuntze var. assamica (Hook.) Steenis, in 1949, and this is the accurate scientific name for Assam tea. The specimen, W. Griffith s.n. (K000939670) at herbarium K, was designated as the neotype of T. assamica in 2021. Seven known heterotypic synonyms of C. sinensis var. assamica and their protologues and types were summarized here. Although Darlington and Ammal proposed the new combination, C. assamica, in 1945, Assam tea is, however, widely accepted as a variety of C. sinensis based on morphological, geological, and phylogenetic analyses. If the specific rank was applied, the earlier heterotypic name of Assam tea, C. theifera published in 1838, would gain priority over C. assamica. Then the widely used epithet “assamica” might be conserved under Art. 14 of the Shenzhen Code. The natural distribution of Assam tea was summarized based on the comprehensive examination of specimens collected from China, India, Laos, Myanmar, Thailand, and Vietnam. The status of natural populations of Assam tea in each country was discussed with the different applications of utilization and conservation.

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Cloning and Expression Analysis of CsWRKY17 Transcription Factor in Tea Plants

LIU Miaomiao, ZANG Liansheng, SUN Xiaoling, ZHOU Zhongshi, YE Meng

Journal of Tea Science 2021, 41 (5): 631-642. DOI: 10.13305/j.cnki.jts.2021.05.001

Abstract （604）

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WRKY transcription factors, a super family of plant transcription factors, play an essential role in the regulation of plant defense responses to herbivores. While the roles of herbivore-related WRKY transcription factors are well established in grass plants, their roles in woody plants are still largely unknown. Here, we cloned a WRKY transcription factor, named CsWRKY17. CsWRKY17 has a full length of 1 141 bp, contains a 987 bp open reading frame, and encodes 328 amino acids. Based on the conserved domain analysis, CsWRKY17 belongs to the WRKY Ⅱ subfamily, containing one conserved WRKY domain and a typical C₂H₂-type zinc finger motif. Homology alignment and phylogenetic tree analysis show that CsWRKY17 has the closest relationship with AtWKRY11 and AtWRKY17 in Arabidopsis thaliana. Moreover, CsWRKY17 exhibited a tissue specific expression, and was also induced by mechanical wounding, tea geometrid (Ectropis oblique) attack, simulated herbivory, and exogenous phytohormone treatments like JA. Transient expression experiments indicate that it might play a role in the nucleus. Taken together, we proposed that CsWRKY17 is a potential regulator of herbivore-induced defense responses against herbivores in tea plants through JA, ABA, GA and BR signaling. Our study paved the way for molecular analysis of herbivore-related WRKY genes in tea plants, and provided a good genetic resource and theoretical basis for future studies of pest-resistant genes and breeding of tea plants.

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Sensory Characteristics of Yellow Large Leaf Tea by Quantitative Descriptive Analysis and Construction of Flavor Wheel

DAI Qianying, YE Yingjun, AN Qi, ZHENG Fangling, XIAO Mingji, XIAO Mengxuan, WANG Huiqiang, ZHANG Haiwei

Journal of Tea Science 2021, 41 (4): 535-544. DOI: 10.13305/j.cnki.jts.2021.04.007

Abstract （599）

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Based on GB/T 16861—1997 and quantitative descriptive analysis, the sensory flavor characteristics of yellow large leaf tea were studied. Generating by panelists freely, the initial 110 attributes were collected. After deleting of the synonymous, vague and adverb qualifiers attributes, combining with M-value and correlation analysis method, 27 attributes were ultimately obtained. The flavor wheel of yellow large leaf tea was drawn with the first-level terms of smell and taste, the second-level terms of aroma, flavor, basic taste and mouthfeel, and 27 attributes as the third-level terms, quantitative reference samples were set for 18 typical flavor attributes, and finally the sensory description vocabulary of yellow large leaf tea with different strength reference materials was established, thus realizing the qualitative and quantitative sensory evaluation of yellow large leaf tea.

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Did the “Belt and Road” Initiative Promote the Export of China's tea? ——An Empirical Study Based on the Generalized DID

WANG Chunxiao, GAO Feng, CHEN Fuqiao, ZENG Liang

Journal of Tea Science 2021, 41 (6): 865-875.

Abstract （587）

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The “Belt and Road” Initiative is a great opportunity for China's tea export. But the existing literatures are short of the evaluation of the policy effect. Based on the panel data of China and 40 major tea importing countries and regions, the difference-in-difference model (Generalized DID) was used to evaluate the promote effect of the “Belt and Road” Initiative to China's tea export. The results show that under the control of other variables, the “Belt and Road” Initiative had a positive effect to promote the growth of the export value of China's tea. Products heterogeneity analysis shows that the “Belt and Road” Initiative significantly promoted the export growth of green tea, but it had no significant effect on black tea. In addition, among the control variables, the improvement of per capital GDP and economic openness could significantly promote the export growth of China's tea. Finally, some suggestions were put forward for China's tea export trade to seize the opportunity.

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Clinical Trial on the Effect of Drinking Jinhua Xiangyuan Tea for 3 Months on the Improvement of Glucose and Lipid Metabolism in A Small Sample Hyperlipidemia Population

SUN Ying, CHEN Xin, YANG Hua, YING Jian, SHAO Danqing, LÜ Xiaohua, XIAO Jie, CHEN Zhixiong, LI Song, QIN Junjie, ZHENG Bin, GAO Jianshe

Journal of Tea Science 2022, 42 (4): 561-576. DOI: 10.13305/j.cnki.jts.2022.04.010

Abstract （585）

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This study is aimed at investigating the clinical effect of drinking Jinhua Xiangyuan tea for 3 months on the glucose and lipid metabolism in a small sample patients with hyperlipidemia (with/without non-alcoholic fatty liver). Jinhua Xiangyuan tea was produced by the new process using Eurotium cristatum. In this study, before-and-after control design was used. The body composition (body weight, BMI, waist hip ratio, percentage of body fat, visceral fat grade), blood biochemical indicators (fasting blood glucose, uric acid, blood lipid), fatty liver, and gut microbiota were examined before and after the test. After drinking Jinhua Xiangyuan tea for 3 months, the body weight, BMI, percentage of body fat, visceral fat grade, serum total cholesterol, low-density lipoprotein cholesterol, and fasting blood glucose of 38 volunteers were significantly reduced (P<0.05). Fatty liver was less severe. Gut microbiota’s diversity and richness were increased. The relative abundance of Phascolarctobacterium, Ruminococcus, Haemophilus and Veillonella were increased, and Dialister and Butyricimonas were decreased. Jinhua Xiangyuan tea could increase the relative abundance of short-chain fatty acid-producing bacteria, increasing short-chain fatty acids, and improving insulin resistance, then improving glucose and lipid metabolism. The results of this study still need to be further confirmed by more rigorous long-term experimental observation.

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Comparison on Chemical Components of Yunnan and Fuding White Tea Based on Metabolomics Approach

GAO Jianjian, CHEN Dan, PENG Jiakun, WU Wenliang, CAI Liangsui, CAI Yawei, TIAN Jun, WAN Yunlong, SUN Weijiang, HUANG Yan, WANG Zhe, LIN Zhi, DAI Weidong

Journal of Tea Science 2022, 42 (5): 623-637. DOI: 10.13305/j.cnki.jts.20220601.001

Abstract （582）

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In order to investigate the differences in chemical compositions between Yunnan white tea and Fuding white tea, 9 Yunnan white tea samples and 6 Fuding white tea samples were studied by ultrahigh performance liquid chromatography-quadrupole orbitrap mass spectrometer (UHPLC-Q-Exactive/MS) combined with sensory evaluation to analyze the non-volatile chemical components of white tea in two places. A total of 109 compounds were structurally identified in this study, including catechins, dimeric catechins, flavonoid glycosides (flavone/flavonol-O-glycosides and flavone/flavonol-C-glycosides), N-ethyl-2-pyrrolidinone-substituted flavan-3-ols (EPSFs), amino acids, phenolic acids, organic acids, alkaloids, lipids, et al. The partial least squares discriminant analysis and heatmap analysis show that there were distinct differences in the chemical components between Yunnan white tea and Fuding white tea. A total of 46 compounds showed significant differences between groups (P<0.05). The contents of epicatechins, dimericcatechins, flavonoid glycosides (kaempferol-3-galactoside, quercetin-3-glucoside, etc.), phenolic acids, organic acids, and lipids were relatively high in Yunnan white tea; while the contents of nonepicatechins, flavonoid glycosides (quercetin-3-galactoside, myricetin-3-galactoside, etc.), amino acids and alkaloids were relatively higher in Fuding white tea, which was speculated to be related with tea cultivars and drying processes. This study provided a theoretical basis for the understanding and recognition of the difference in the chemical substance and flavor quality of different white tea between two places, as well as the identification of white tea origins.

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Decomposition Characteristics of Lignin and Cellulose in Different Litters of Ecological Tea Gardens in Mountainous Areas of Guizhou

LIU Shaqian, YANG Rui, HOU Chunlan, MA Juebing, GUO Jiarui

Journal of Tea Science 2021, 41 (5): 654-668. DOI: 10.13305/j.cnki.jts.2021.05.003

Abstract （572）

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The litter decomposition bag method was used to analyze the decomposition of five single litter types and nine mixed litter types in Guizhou Jiu'an Ecological Tea Garden with Cinnamomum glanduliferum, Betula luminifera, Cunninghamia lanceolata and Pinus massoniana leaf litters and Camellia sinensis trims as the research objects. The decomposition rate and release characteristics and differences of lignin and cellulose were studied. The results show that in a single type of litter, the litter decomposition rate of broad-leaved species was higher than that of coniferous species. The lignin content of litter of broad-leaved species showed an increasing trend. While that of coniferous species showed a downward trend as a whole. The content of cellulose in litter also showed a decreasing trend. According to the analysis of the release law of lignin and cellulose, both single litter release law and mixed litter cellulose release law were direct release. There were three release laws for single litter lignin, and 5 laws for mixed litter lignin. According to the analysis of the decomposition characteristics of 9 kinds of mixed litter, 44.4% of mixed litter decomposition showed additive effect, 11.2% mixed decomposition showed antagonistic effect, and 44.4% mixed decomposition showed synergistic effect. While 22.2% of mixed litter lignin release showed promoting release, and 55.6% mixed litter lignin release promoted the enrichment. A total of 11.1% of the mixed litter cellulose appeared to promote the enrichment, and 22.2% of the mixed litter cellulose was to promote the release. This study provided a theoretical basis for further maintaining the fertility in tea gardens.

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A Study of Xinyang Maojian Tea Water Extracts on Relieving Lung Injury Caused by PM_2.5

LIU Jianjun, LI Meifeng, ZHANG Jing, TIAN Lili, DENG Yanli, LIN Haiyan, HUANG Jian′an, LIU Zhonghua

Journal of Tea Science 2021, 41 (4): 525-534. DOI: 10.13305/j.cnki.jts.2021.04.006

Abstract （563）

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In this study, the healthy male sprague-dawley (SD) rats were taken as experimental subjects, and the water extracts of Xinyang Maojian tea were used as test substances, while intratracheal instillation of PM_2.5 suspension was established as chronic pulmonary injury model. Rats serum and biochemical indexes of bronchoalveolar lavage fluid (BALF) were tested. The results show that the tea extracts had antagonism effects on the reduce of rats growth rate and the lung injury caused by PM_2.5. Furthermore, the tea water extracts could effectively lower the increase of IL-1β, IL-6, TNF-α, IgG and the activity of LDH, and keep the activity of SOD in rats serum and BALF, showing a dose-dependent effects.

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Identification of LOX Gene Family in Camellia sinensis and Expression Analysis in the Process of White Tea Withering

LIN Xinying, WANG Pengjie, CHEN Xuejin, GUO Yongchun, GU Mengya, ZHENG Yucheng, YE Naixing

Journal of Tea Science 2021, 41 (4): 482-496. DOI: 10.13305/j.cnki.jts.2021.04.004

Abstract （555）

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Aliphatic compounds are an important part of plant aromatic substances and play an important role in the composition of white tea aroma. This study used bioinformatics methods to identify the LOX gene family in the chromosome-level tea plant genome database, and obtained 12 tea plant LOX gene family members, named CsLOX1-CsLOX12. The 12 tea plant LOXs are mainly located in the cytoplasm or chloroplast. The encoded proteins have the same characteristic domains and conserved motifs. Phylogenetic tree analysis shows that the LOX gene family is divided into two subfamilies: 9-LOX and 13-LOX. CsLOX2, CsLOX3, CsLOX4, and CsLOX7 belong to 9-LOX subtypes, and the rest belong to 13-LOX subtypes. Gene structure analysis shows that CsLOX1 contains 8 exons, the rest contain 9 exons. The transcriptome data analysis of different tissues shows that the family genes are highly expressed in the tender and mature leaves of tea plants. The upstream promoter region analysis finds a large number of cis-acting elements closely related to plant development, light response, hormone and stress response. Fluorescence quantitative PCR detection reveals that the CsLOX genes were expressed to varying degrees under drought, low temperature and MeJA hormone treatment. Under the treatment of different withering time of white tea, the expression levels of CsLOX1, CsLOX3, CsLOX5, CsLOX7, CsLOX8, CsLOX9, CsLOX11 and CsLOX12 were induced, with the peaks at 4 h (up to 27-fold increase). The results of this study show that members of the CsLOX gene family participate in the regulation of the formation of aliphatic aromas during the process of white tea withering, laying a foundation for understanding the molecular mechanism of aroma formation during tea processing.

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The Influencing Factors and Trade Efficiency of China Tea Export: Based on Stochastic Frontier Gravity Model

ZHANG Fei, GUAN Xi, ZHU Rongjun

Journal of Tea Science 2021, 41 (3): 430-438. DOI: 10.13305/j.cnki.jts.2021.03.009

Abstract （551）

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Based on the stochastic frontier gravity model and trade non-efficiency model, using panel data of 37 representative countries (regions) from 2001 to 2017, influencing factors and trade efficiency of China tea export were analyzed. The results show that China tea export efficiency had a rising tendency, but the overall export efficiency was at a low level and presented regional imbalance. The China tea export efficiency with the developed economies was relatively high, but the tea trade efficiency with countries along "the Belt and Road" was at a very low level. The failure to realize the full potential of China tea export efficiency mainly came from the loss of technical efficiency. The increase of domestic supply, the expansion of importing market capacity and the reduction of trade cost were all conducive to improve China tea export efficiency. To some extent, the business environment improvement of importing markets could offset the impact of trade inefficiency. Free trade agreement had not yet played a positive role in China tea export.

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Genetic Diversity and Population Structure of Wild and Cultivated Camellia taliensis Populations

MAO Juan, JIANG Hongjian, YANG Rubing, LI Chongxing, MA Chengying, CHEN Liang, MA Jianqiang

Journal of Tea Science 2021, 41 (4): 454-462. DOI: 10.13305/j.cnki.jts.2021.04.002

Abstract （550）

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Camellia taliensis is a wild relative of tea plants (C. sinensis). Understanding of the genetic diversity and population structure of Camellia taliensis is important and helpful for protecting and utilizing these germplasm resources. In this study, a set of 30 core SSR markers derived from tea plants were used for genetic analysis of three representative wild and cultivated C. taliensis populations. The results show that all SSR markers successfully yielded specific amplification, with a range of polymorphic alleles from 2 to 14. The PIC value was between 0.041 and 0.877, with an average of 0.491. The three C. taliensis populations showed moderate levels of genetic diversity, and it was relatively lower for the Daxueshan (DXS) wild population. The inbreeding coefficient (Fis) of Xiangzhuqing (XZQ) and Baiyingshan (BYS) cultivated populations were 0.728 and 0.913 respectively, which meant high levels of inbreeding. Pairwise comparisons of the genetic differentiation index of three populations were low (Fst<0.15), while the rates of gene flow were high (Nm>1). The results of AMOVA exhibite that 94.1% of the genetic variation was within population. The genetic distances of wild and cultivated C. taliensis individuals were relatively higher. The genetic background of wild population was similar, while it was complex for cultivated populations. Seven individuals of BYS population were possibly originated from hybridization and introgression between C. taliensis and C. sinensis var. assamica.

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The Effect of Initial Microwave Drying on Black Tea Quality

CUI Lidan, ZHANG Xianglin, XIANG Xi, LI Lanlan, QU Qingyun, XU Yangyang, WANG Jiguo, LIU Feng, GONG Zhihua, XIAO Wenjun

Journal of Tea Science 2021, 41 (3): 406-418. DOI: 10.13305/j.cnki.jts.2021.03.007

Abstract （542）

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Flushes of two leaves and a bud of tea cultivar ‘Bixiangzao’ were picked during late summer and early autumn as raw material. During the black tea processing, initial microwave drying was adopted instead of conventional initial air drying. Seventeen processing groups were set up with independent variables of microwave density, time duration and piled leaf depth. Sensory quality, taste compounds and aroma compounds of the black tea were investigated and considered as quality criteria. The results show that compared with conventional initial air drying, the black tea processed with microwave power density of 600 W, 3 min, and piled leaf depth of 2 cm had the best sensory quality. Meanwhile, it showed a significant increase in the contents of theaflavins, thearubigins, catechins, ester catechins, EGCG, amino acids, caffeine and soluble sugar (P<0.05), while presented a significant decrease in the contents of tea polyphenols and theabrowmines (P<0.05). The number of aroma compounds increased from 43 to 50. The relative contents of floral and fruit scent compounds such as linalool and phenylethanol increased significantly (P<0.05). Furthermore, several novel sweet and flower scent compounds including (Z)-3,7-dimethyl-2,6-octadien-1-ol, 2,6,6-trimethyl-1,3-cyclohexadiene-1-formaldehyde, 2,6,6-trimethyl-1-cyclohexene-1-formaldehyde, and eugenol were identified. In conclusion, the initial microwave drying benefits the quality of black tea.

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Identification of Alcohol Dehydrogenase Gene Family and Their Expression Analysis in the Withering Process of White Tea

GU Mengya, WANG Pengjie, CHEN Xuejin, ZHENG Yucheng, GUO Yongchun, LIN Xinying, GAO Ting, HOU Binghao, YE Naixing

Journal of Tea Science 2021, 41 (3): 302-314. DOI: 10.13305/j.cnki.jts.2021.03.002

Abstract （541）

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Alcohol dehydrogenase (ADH) plays an important role in the formation of tea aroma as one of the key enzymes in the synthesis of fatty acid metabolism pathway. In this study, 19 CsADH gene family members were identified from the chromosome level genome database of tea plants for the first time. Bioinformatics analysis shows that the members of ADH gene family were divided into six subfamilies. Collinearity analysis shows that there were 2, 4 and 12 pairs of collinearity between ADH gene family of Camellia sinensis and Arabidopsis thaliana, Vitis vinifera and Actinidia chinensis, respectively. The tea ADH gene family contains 1-13 exons, which encode 236-669 amino acids with molecular weight of 26.15-73.83 kDa. It is mainly located in cytoplasm and chloroplast, and only CsADH1is located in nucleus. In addition, a large number of cis-acting elements closely related to light responsive, plant growth, stress and phytohormone responsive were found in the upstream promoter region. Fluorescence quantitative detection shows that the expression of CsFDH2 was the highest at 4 h of withering. The expressions of CsADH4 and CsADH10 were the highest at 32 h of withering, which were 4.11 and 3.54 times that of the control respectively. The expression of CsADH3 reached the peak at 48 h of withering, which was slightly higher than that at 32 h of withering. The expression of CsADH-like1 reached the highest value at 40 h of withering. The highest expression of CsADH-like3 was at 24 h of withering. This study provided a reference for exploring the molecular mechanism of alcohol dehydrogenase genes acting on the formation of aliphatic aromatic substances in the withering process of white tea.

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Analysis of Genetic Diversity and Population Structure of 32 Tea Landraces in China

LI Changle, GE Yue, YAN Meilin, LI Hui, LIN Qingqing, WANG Pu, ZHAO Hua, WANG Mingle, WANG Yu, GUO Fei, NI Dejiang

Journal of Tea Science 2021, 41 (5): 619-630. DOI: 10.13305/j.cnki.jts.20210804.002

Abstract （540）

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Tea plant populations are natural populations of tea plants. They are cultivated in specific production areas and contain individuals with different economic and biological traits. There are great differences among individuals and there are many types. They are important materials for studying the evolutionary relationship and breeding of tea plants. In this study, 30 pairs of SSR primers distributed on 15 linkage groups were selected to analyze the genetic diversity and population structure of 32 tea plant populations from 12 provinces, in order to provide a reference for the selection of tea breeding parents and the inference of evolution route. In this study, a total of 149 alleles were obtained with an average of 5.96 for each SSR marker. The average polymorphism information content of primers was 0.660. Shannon's diversity index of 32 tea populations ranged from 0.691 to 1.089, with an average of 0.954. The observed heterozygosity ranged from 0.253 to 0.633, with an average of 0.510. The expected heterozygosity ranged from 0.430 to 0.653, with an average of 0.590. The average genetic differentiation coefficient (Fst) of tea plant population was 0.205, indicating a high level of genetic differentiation. The results of clustering based on Nei's genetic distance and population structure analysis were consistent. The germplasm to be tested was divided into 4 major types, with obvious regional distribution.

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Intervention Effects of L-Theanine on the Damage of Hippocampus and Gut in CUMS Depressed Rats

CHEN Meiyan, LIU Fen, LIN Yong, ZUO Gaolong, ZUO Yingpeng, LIU Zhonghua

Journal of Tea Science 2021, 41 (4): 511-524. DOI: 10.13305/j.cnki.jts.2021.04.005

Abstract （536）

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Using SPF-grade SD male rats as experimental animals, a rat model of chronic unpredictable mild stress (CUMS) was established and different doses of L-theanine were given intragastrically for intervention. Then, the effects of L-theanine on the depression-like behaviors, histopathological changes and the levels of interleukin-6 (IL-6), tumor necrosis factor alpha (TNF-α), 5-hydroxytryptamine (5-HT) and glucagon-like peptide 1 (GLP-1) contents of hippocampus and gut were observed and evaluated, which aimed to explore the intervention effects of L-theanine on the structural damage and dysfunction of hippocampus and gut in CUMS depressed rats. The results show that, compared with the model group, pretreatment with different doses of L-theanine improved the body weight,sugar-water preference, number of crossing and rearing, activity in water, number of entering the light box and the duration time of ratsat different degrees, especially the middle-dose group (100 mg·kg^-1) reached a significant level. L-theanine effectively repaired hippocampal neuron damage caused by CUMS, reduced IL-6 and TNF-α levels in serum, colon and cecum and attenuated the damage and inflammation degree of the colon and cecum tissues, and the middle-dose group also exhibited better effect. L-theanine could increase the contents of 5-HT and GLP-1 in hippocampus, cerebral cortex and colon of CUMS rats, and reached significant levels under some conditions. These results indicate that L-theanine can effectively improve the depression-like behavior, structural damage and dysfunction of hippocampus and gut in CUMS model rats, and its regulation of ‘gut-brain axis’ may be the action mechanism of anti-depression.

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Volatile Organic Compounds from Fresh Tea Leaves and Their Fumigation Antifungal Activities on Fungal Pathogens of Tea Plants

ZHI Yanan, XU Yunfei, ZHU Mingxing, WANG Chunsheng, JIN Yinli, CHEN Lijun

Journal of Tea Science 2021, 41 (3): 371-378. DOI: 10.13305/j.cnki.jts.2021.03.005

Abstract （535）

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In order to determine the relationship between volatile organic compounds (VOCs) from fresh tea leaves and the main fungal pathogens of tea plants, the VOCs from fresh tea leaves were extracted and analyzed by HS-SPME-GC-MS. The fumigation antifungal activities of volatile monomers from fresh tea leaves against four fungal pathogens including Botryosphaeria dothidea, Colletotrichum camelliae, Colletotrichum gloeosporioides, Pestalotiopsis theae were also studied. The results show that 28 chemical compounds were found from VOCs of fresh tea leaves, and 19 of them were characterized, accounting for 94.405% of the total VOCs. The main chemical compounds were hexanoic acid, 3-hexenyl ester, (Z)-hexanoic acid-3-hexenyl ester (18.395%), leaf acetate (16.935%), ocimene (12.615%), and cis-3-hexenyl butyrate (11.210%). Cis-3-hexenyl butyrate exhibited strong fumigation antifungal effect on the four tested fungal pathogens, and the EC₅₀ were lower than 61.29 μL·L^-1. In conclusion, cis-3-hexenyl butyrate can be used as a potential fumigant control of tea diseases.

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Study of Characteristic Indexes and Fatty Acid Composition in Big-leaf Tea Plant (Camellia sinensis var. assamica) Seed Oils from Yunnan Province

WU Wanfu, LYU Shidong, YANG Xuefang, LI Yue, ZHANG Jiguang

Journal of Tea Science 2021, 41 (4): 463-470. DOI: 10.13305/j.cnki.jts.20210622.001

Abstract （525）

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The characteristic parameters (refractive index, relative density, iodine value, saponification value) and fatty acid composition in five big-leaf tea plant (Camellia sinensis var. assamica) seed oils from Yunnan Province and other eight common edible vegetable oils were analyzed by chemical titration and gas chromatography (GC). The results show that the refractive index of the five big-leaf tea plant (Camellia sinensis var. assamica) seed oils ranged from 1.462 9-1.463 4. The relative density ranged from 0.914 8~0.916 7, iodine value was 859-903 g·kg^-1, saponification value was 189.0-193.2 g·kg^-1 palmitic acid contents were 14.29%-15.75%, oleic acid contents were 57.83%-61.41%, linoleic acid contents were 18.81%-23.11%. The saturated fatty acid contents ranged from 17.6% to 19.8%. Unsaturated fatty acid contents were 80.2%-82.4%. Overall, the fatty acid composition of big-leaf tea plant (Camellia sinensis var. assamica) seed oil was similar as the Camellia oleifera seed oil and olive oil. The ratio of saturated fatty acid, monounsaturated fatty acid and polyunsaturated fatty acid was about 1∶3∶1. Big-leaf tea plant (Camellia sinensis var. assamica) seed oil has the potential value for research, development and promotion.

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Research on the Changes of China's Tea Production Layout

WU Qinyao, YANG Jiangfan, LIN Cheng, GUAN Xi

Journal of Tea Science 2022, 42 (2): 290-300. DOI: 10.13305/j.cnki.jts.20211210.001

Abstract （521）

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Based on the agricultural location theory, comparative advantage theory and rational "economic man" hypothesis, a theoretical analysis framework taking cultural factors and factors affecting the changes in China's tea production layout into account was constructed using data from 16 tea-producing provinces across the country from 1993 to 2018. The panel data of the district expounded the characteristics and laws of the changes in China's tea production layout, and clarified the main influencing factors and driving mechanisms that affected the changes in China's tea production layout. The results show that: (1) After the reform and opening up, from 1993 to 2018, China's tea industry had agglomerated and expanded in terms of production scale, and the tea production space had changed significantly, with significant differences in characteristics. (2) The layout of tea yield was based on natural resources, consumer demand, and culture. The factors like technological progress and social and economic factors had a profound impact on the layout of tea production over time, and resulted in differences in tea-producing provinces across the country. (3) Natural resources and technological progress were the basis and prerequisite for changes in the layout of tea production. The decisive conditions for changes in the layout of tea production were consumer demand and socio-economic factors. Brand building and policy support were also important supplementary factors for the current development of the tea industry. On this basis, this article proposed to optimize the layout of tea production according to local conditions, strengthen the protection of land resources, rationally plan the area of tea gardens, maintain the continuous and stable development of the tea industry, attach importance to technological innovation and application to improve the level of tea yields and use the inter-regional interaction of tea production to achieve policy recommendations such as improving the overall efficiency of the tea industry.

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Cloning and Expression Analysis of CsCML16 in Tea Plants (Camellia sinensis) under Low Temperature Stress

CHEN Siwen, KANG Rui, GUO Zhiyuan, ZHOU Qiongqiong, FENG Jiancan

Journal of Tea Science 2021, 41 (3): 315-326. DOI: 10.13305/j.cnki.jts.20210514.001

Abstract （504）

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Calmodulin-like proteins (CMLs) are important calcium signaling proteins in plants, which play a pivotal role in abiotic stress. In this study, one-year-old tea cutting seedlings of ‘Longjing43’, ‘Fuding Dabai’ and ‘Huangjinya’ were used as research materials. The physiological changes of the three tea cultivars were explored to preliminarily screen the cold-resistance tea cultivar. The CsCML16 gene was cloned to analyze its expression patterns in different cold-tolerance tea cultivars under low temperature stress. The results show that ‘Longjing43’ had the highest cold tolerance under low temperature stress, followed by ‘Fuding Dabai’ and ‘Huangjinya’. CsCML16 gene was cloned from ‘Longjing43’. Sequence analysis shows that the CDS length of CsCML16 is 480 bp, encodes 160 amino acids, contains EF-hand conserved domains with molecular weight of 17.58 kDa. Subcellular localization assay indicates that CsCML16 localized in the nucleus and plasma membrane. Quantitative real-time PCR analysis reveals that CsCML16 gene was involved in the regulation of tea plants in response to low temperature stress, and its expression levels varied with tea cultivars with different cold tolerance. This study provided a basis for further study on the biological function of CsCML16 gene.

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Dynamic Changes of Physiological Responses and Antioxidant Enzyme Activities in Tea Root System under Severe Shading and Removal of Shading

JIAO Haizhen, SHAO Chenyu, CHEN Jianjiao, ZHANG Chenyu, CHEN Jiahao, LI Yunfei, SHEN Chengwen

Journal of Tea Science 2021, 41 (5): 695-704. DOI: 10.13305/j.cnki.jts.2021.05.005

Abstract （500）

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Shading is one of the important measures to improve the quality of summer and autumn tea. There were a lot of studies on the effect of shading on tea leaves, but there were few reports on the root system. In this study, a pot experiment was used to explore the dynamic changes of physiological indexes and antioxidant enzyme activities of ‘Xiangfeicui’ and ‘Jinxuan’ under 95% shading treatment. Data were collected after shading for 0, 4, 12 d and the 4 d after regaining light. The results show that the number of new absorbing roots and lateral roots of tea plants increased after shading for 12 d, and decreased on the 4th day after regaining light. The trends of root vigor changes were the same. The soluble sugar content of ‘Xiangfeicui’ increased after shading, and the soluble sugars of ‘Xiangfeicui’ and ‘Jinxuan’ increased by 5.82% and 8.04% on the 4th day after regaining light. On the 4th day of heavy shading, the APX and POD activities of the two cultivars reached the peaks. On the 12th day of shading, the activities of SOD and APX the highest. The APX activity of tea roots after regaining light was significantly higher than that without shading. This study reveals that the roots of tea plants were osmotically regulated by increasing the content of soluble sugars, enhancing root vigor to absorb and transport nutrients, and increasing antioxidant enzyme activities to scavenging free radicals in response to heavy shade environments. Under a shading environment (95%), ‘Jinxuan’ was more shade-tolerant, and regaining light might cause a certain degree of stress to the roots of tea plants.

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Differences of Phenolic Components in Puer Raw Tea with Various Storage Periods and Their Effects on the in vitro Antioxidant Capacities

MA Bingsong, WANG Jiacai, XU Chengcheng, REN Xiaoying, MA Cunqiang, ZHOU Binxing

Journal of Tea Science 2022, 42 (1): 51-62.

Abstract （497）

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To explore the changes of phenolic compounds and other quality components and their influences on antioxidant abilities during the storage and aging of puer tea, contents of 17 phenolic compounds, 3 purine alkaloids and other quality components in 18 puer tea samples of 6 series with 3 different storage periods were determined by high performance liquid chromatography (HPLC) and other methods. Additionally, in vitro antioxidant abilities including ferric ion reducing antioxidant power (FRAP), DPPH scavenging ability (DPPH), ABTS free radical scavenging capacity (ABTS), hydroxyl radical scavenging ability (HSA) and superoxide anion radical scavenging ability (SSA) were determined in all puer raw teas. Combined with sensory evaluation results, multivariate statistical analyses including principal component analysis (PCA) and orthogonal partial least square-discriminate analysis (OPLS-DA) were used to realize the discrimination between new and aged tea during the storage. One-way analysis of variance (ANOVA) showed 7 catechins were highly significantly (P<0.01) decreased, while ellagic acid and flavonoids like quercetin, luteolin and kaempferol levels were also highly significantly (P<0.01) increased during the storage and aging. And, new puer tea had the highest FRAP, DPPH, ABTS, but the lowest SSA compared with the aging and aged puer teas. Bivariate correlation analysis revealed that the catechins including catechin (C), gallocatechin (GC), epigallocatechin (EGC), epicatechin gallate (ECG) and epigallocatechin gallate (EGCG) impacted FRAP, DPPH and ABTS of puer raw tea during the storage and aging.

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Effects of Biochar Application on Soil Properties and Fungi Community Structure in Acidified Tea Gardens

WANG Yixiang, HUANG Jiaqing, YE Jing, LI Yanchun, LIN Yi, LIU Cenwei

Journal of Tea Science 2021, 41 (3): 419-429. DOI: 10.13305/j.cnki.jts.2021.03.008

Abstract （492）

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The impact of long-term biochar application on soil improvement and fungal community structure in acidified tea gardens is still unclear. Five years after biochar application, the changes of soil properties and fungi community structure in tea gardens with different biochar applications (0, 2.5, 5, 10, 20 and 40 t·hm^-2) were studied. The results show that after applying biochar for 5 years, the pH value of soil increased by 0.16 to 1.11 units, the soluble organic carbon content increased by 52.6% to 92.3%, and the contents of ammonium nitrogen and nitrate nitrogen in soils with 10 t·hm^-2 biochar application were the highest. The changes of soil properties further affected the fungi community structure. The Chao index, ACE index and Shannon index of the fungi community firstly increased and then decreased with the increase of biochar amount. The effect of biochar application on the secondary fungi (LDA value<3.50) was higher than that on dominant fungi (LDA value>3.50). In addition, the relative abundance of Mortierella, Trichoderma and Chaetomium increased after the application of biochar, but the relative abundance of Melanconiella decreased.

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Virulence Difference of Two Strains of EoNPV Isolates to Ectropis obliqua and Ectropis grisescens

XU Bin, HAN Guangjie, QI Jianhang, LI Chuanming, XU Jian, LU Yurong, LIU Qin

Journal of Tea Science 2021, 41 (4): 545-552. DOI: 10.13305/j.cnki.jts.2021.04.008

Abstract （489）

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The virulence differences of Ectropis obliqua nucleopolyhedrovirus (EoNPV) from different isolates to Ectropis obliqua and Ectropis grisescens were analyzed, which provided a basis for effectively improving the control effect of EoNPV. The virulence of EoNPV Zhejiang strain (EoNPV-ZJ) and EoNPV Jiangxi strain (EoNPV-JX) to third instar larvae of E. obliqua and E. grisescens were determined by leaf dipping. The homologous regions (hrs) of EoNPV-ZJ and EoNPV-JX were further sequenced and analyzed by multiple sequence alignment. The results indicate that the 14 d LC₅₀ of EoNPV-JX to E. grisescens and E. obliqua were 5.95×10⁶ PIB·mL^-1 and 3.14×10⁶ PIB·mL^-1, respectively, while the 14 d LC₅₀ of EoNPV-ZJ to the two tea geometrid moths were 1.13×10⁷ PIB·mL^-1 and 5.04×10⁶ PIB·mL^-1, respectively. The hr1 of EoNPV-JX and EoNPV-ZJ were both 1 795 bp in size, containing 11 complete palindrome sequences, and hr3 were both 665 bp in size, containing 3 complete palindrome sequences, which were the same as EoNPV Anhui strain (EoNPV-AH). However, the hr2 regions of the three strains were different. The hr2 of EoNPV-JX was 864 bp in size and contained 7 complete palindrome sequences, and it was 1 168 bp in size and contained 12 complete palindrome sequences in EoNPV-ZJ, all of which were less than the 18 complete palindrome sequences of hr2 in EoNPV-AH. Our study suggests that the virulence of different strains of EoNPV to E. obliqua were higher than that of its related species, E. grisescens, while the toxicity of EoNPV-JX to E. grisescens was more than that of EoNPV-ZJ. The sensitivity of E. obliqua to EoNPV was higher than that of E. grisescens. The virulence of EoNPV might be related to the number of palindromes of hr2.

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The Control Efficiency of Afidopyropen to Tea Green Leafhoppers and Evaluation of Residue in Tea

GUO Mingming, LI Zhaoqun, LIU Yan, RAO Fuqiang, YU Jiawei, WU Luchao, ZHOU Li, CHEN Zongmao

Journal of Tea Science 2022, 42 (3): 358-366. DOI: 10.13305/j.cnki.jts.20220506.002

Abstract （477）

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Afidopyropen is a novel biogenic insecticide derived from the natural fermentation product. This study aimed to evaluate the feasibility of afidopyropen for tea green leafhoppers (Empoasca onukii Matsuda) control and tea safety after the application of afidopyropen in tea garden. The dosage field trials and demonstration trials were conducted to evaluate the control efficiency of afidopyropen to tea green leafhoppers and the terminal residues in tea. The results of the dosage field trials in 2 locations show that 50 g·L^-1 afidopyropen dispersible concentrate was more effective against the green leafhoppers than chlorfenapyr which was commonly used pesticide for the green leafhoppers control. At the dosages of 15.00 g·hm^-2 and 22.50 g·hm^-2, control efficiencies were 88.6%-93.4% on the 1st day after treatment and 75.5%-85.5% on the 14th day, demonstrating a quick control effect and good persistence. At the dosage of 18.75 g·hm^-2 in 7 locations, the control efficiencies were 88.9%-100.0% on the 3rd day after treatment, and 60.2%-100.0% on the 14th day, which were better than the local commonly used pesticides. The terminal residues of afidopyropen in green tea ranged from 0.17-0.64 mg·kg^-1 on the 7th day after the application, the leaching rate of afidopyropen from dry tea to tea brew ranged from 17.1%-19.1% during the brewing process, and the risk quotient values were far less than 1, indicating a very low health risk caused by the afidopyropen intake through drinking tea. In conclusion, afidopyropen is suitable for resistance management and comprehensive management of tea green leafhoppers with the advantages of low dosage, high-efficiency and low-healthy risk for tea consumer.

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