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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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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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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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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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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Tea Buds Detection Model Using Improved YOLOv4-tiny

FANG Mengrui, LÜ Jun, RUAN Jianyun, BIAN Lei, WU Chuanyu, YAO Qing

Journal of Tea Science 2022, 42 (4): 549-560. DOI: 10.13305/j.cnki.jts.2022.04.009

Abstract （468）

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Precise detection of tea buds is a prerequisite for intelligent mechanical picking of tea. Aiming at the problems of poor salience and high missed detection rate of small-scale buds caused by different sizes of tea leaves and the cover of other tea leaves, this paper proposed a kind of tea buds detection model based on improved YOLOv4-tiny. In this model, a 52×52 shallow feature layer was added in the neck network to promote the attention of YOLOv4-tiny network to small target buds. A convolutional block attention module (CBAM) was introduced to suppress the background noise and improve the salience of buds, and a bidirectional feature pyramid network (BiFPN) was used to integrate characteristic information of different scales, so as to propose the YOLOv4-tiny-Tea, a high performance light weight tea buds detection model. The results of model training and performance testing on the same training set and test set show that for the YOLOv4-tiny-Tea model, the detection precision and recall rate were 97.77% and 95.23% respectively, which were 5.58% and 23.14% higher than those before modification. An ablation experiment verified the effectiveness of the modified network structure in detecting different scales of buds, and a comparison of YOLOv4-tiny-Tea model with three YOLO algorithms found that the F1 value of YOLOv4-tiny-Tea model was 12.11%, 11.66% and 6.76% higher than F1 values of YOLOv3, YOLOv4 and YOLOv5l models respectively. The number of parameters in YOLOv4-tiny-Tea model was merely 13.57%, 13.06% and 35.05% of the three network models. The experimental results demonstrate that the method proposed in this paper effectively improved the detection precision of buds under different scales, greatly reduced the missed detection rate of buds for small size or under shading, and significantly bettered the detection precision based on a lightweight computation overhead. Therefore, the method can meet the needs of agricultural robots for real-time detection and embedded development, thus providing a reference for intelligent tea buds picking.

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Effects of Light Waves on the Aroma Substances of Fresh Tea Leaves in Summer and Autumn During Spreading and the Quality of Final Green Tea

LIU Jianjun, ZHANG Jinyu, PENG Ye, LIU Xiaobo, YANG Yun, HUANG Tao, WEN Beibei, LI Meifeng

Journal of Tea Science 2022, 42 (4): 500-514. DOI: 10.13305/j.cnki.jts.20220520.001

Abstract （457）

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The rough aroma is an important factor affecting the quality of summer and autumn green tea. In order to improve the quality of summer and autumn green tea, this experiment took Fuding Dabai tea as the research object, and irradiated fresh leaves in vitro with red light, yellow light, blue light and purple light, and the nature light was used as the control. Headspace solid-phase microextraction-gas chromatography-mass spectrometry (HS-SPME-GC-MS) was used to qualitatively and quantitatively detect the volatile components of the fresh leaves. Supplemented by Hierarchical Cluster Analysis (HCA), Principal Component Analysis (PCA) and Partial least squares discriminant analysis (PLS-DA), the optimal light wave and key substances that promote the formation of tea's floral and fruity aroma were identified. The results show that different light qualities had significant effects on the types and contents of aroma substances. A total of 36 aroma substances were identified from 5 samples, of which alcohols and terpenes were the most numerous, and the average content of esters was the highest, followed by alcohols. Red light was the best light to promote the accumulation of tea aroma components. 3-Carene, β-Myrcene and phenylethyl alcohol were the key substances for improving the aroma in tea leaves. All light treatments could promote the free amino acids and caffeine in fresh leaves, and reduce the ratio of phenol to ammonia. After light treatment, the fresh and floral flavor of green tea was more obvious, and the taste was fresh. The comprehensive score of the tea samples treated with red light was the best. The research has shown that red light irradiation of fresh tea leaves in summer and autumn could increase the types and contents of tea aroma substances, significantly improve the key substances in the formation of flower and fruit aroma, and increase the freshness of tea soup.

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Analysis of the Saponin Contents and Composition in Tea Seeds of Different Germplasms

CHEN Yuhong, GAO Ying, HAN Zhen, YIN Junfeng

Journal of Tea Science 2022, 42 (5): 705-716. DOI: 10.13305/j.cnki.jts.2022.05.005

Abstract （452）

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Tea saponins are abundant in the seeds of Camellia sinensis with specific biological activities. Their contents and composition in tea seeds of different germplasms remain unclear. In this study, seeds from 21 tea germplasms were collected from the same region of Zhejiang and used as experimental materials to determine the basic characteristics, saponin contents and composition. Correlation analysis between germplasm and saponin composition was also performed. The results show that the seed weight, shell kernel ratio and saponin content of different tea seeds were significantly different (P<0.05). The saponin content detected by UV spectral method and HPLC ranged from 30.82% to 48.16% and 16.93% to 31.82%, respectively. ‘Huangguanyin' had the highest saponin content in tea seeds. Totally 68 tea seed saponin monomers were detected simultaneously using ultrahigh performance liquid chromatography-quadrupole orbitrap mass spectrometer（UHPLC-Q-Exactive/MS）. Theasaponin E1 had the highest relative intensity. Orthogonal partial least squares discriminant analysis (OPLS-DA) shows that the 21 tea seed germplasms can be distinguished into 2 groups according to tree type with 21 different Camelliasaponin B1/B2, Theasaponin A5/A6, Camelliasaponin C1/C2 and Assamsaponin G were the most significant characteristic substances of semi-tree form and arbor form resources. The results of the study laid the foundation for the selection and value-added utilization of tea seed saponins.

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Characterization of the Key Aroma in Corn-scented Congou Black Tea Manufactured from Camellia nanchuanica by Sensory Omics Techniques

OUYANG Ke, ZHANG Cheng, LIAO Xueli, KUN Jirui, TONG Huarong

Journal of Tea Science 2022, 42 (3): 397-408. DOI: 10.13305/j.cnki.jts.20220506.003

Abstract （442）

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Camellia nanchuanica is endemic to Nanchuan district, Chongqing and has a high development value. In this study, the characteristic aroma of corn-scented Congou black tea from Camellia nanchuanica was analyzed by headspace-solid phase microextraction, gas chromatography-mass spectrometry (HS-SPME-GC/MS), gas chromatography-olfactometry (GC-O), odor activity value (OAV) and aroma character impact value (ACI). The results show that 22 key aroma compounds with OAVs≥1 were identified in the corn-scented black tea. Dimethyl sulfide had the highest OAV (1 187.32), and its ACI was 51.56%. A total of 26 odor-active compounds were perceived by GC-O. Dimethyl sulfide had a higher olfactory intensity, which had a “corn-like” odor. The results obtained by the OAV approaches and by GC-O method for key aroma identification were in good agreement. The importance of dimethyl sulfide in corn-scented black tea was verified by aroma recombination and omission test. Focusing on the analysis of the active aromas of corn-scented black tea would provide a theoretical basis for the quality control of this prized tea.

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Functional Identification of CsbHLH024 and CsbHLH133 Transcription Factors in Tea Plants

LIU Renjian, WANG Yuyuan, LIU Shaoqun, SHU Canwei, SUN Binmei, ZHENG Peng

Journal of Tea Science 2022, 42 (3): 347-357. DOI: 10.13305/j.cnki.jts.2022.03.001

Abstract （393）

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Tea plant leaf trichomes contain various secondary metabolites and play an important role in the tea appearance quality as well as the response of tea plants to biotic and abiotic stresses. In this study, the function of leaf trichome-related genes CsbHLH024 and CsbHLH133 were analyzed using Bimolecular Fluorescent Complimentary (BiFC), GUS staining and overexpression experiments. The results show that CsbHLH024/CsbHLH133 and CsTTG1 could interact in plants, and their promoters could drive downstream gene expression in leaf tissues. They were further transformed into wild Arabidopsis thaliana (Col) and corresponding homozygous mutants, respectively to get overexpression lines. Both genes could affect the leaf trichome formation in Arabidopsis thaliana, restore the phenotype of the mutants, and induce the expression levels of trichome-related genes. This study provided a theoretical basis for further research on the molecular regulation mechanism of trichome formation in tea leaves.

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Genetic and Phylogenetic Analysis for Germplasm Resources of Camellia sinensis from Wuzhou City

WANG Liubin, HUANG Liyun, TENG Cuiqin, WU Liyun, CHENG Hao, YU Cuiping, WANG Liyuan

Journal of Tea Science 2022, 42 (5): 601-609. DOI: 10.13305/j.cnki.jts.2022.05.004

Abstract （385）

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Based on the SSR markers, the genetic diversity and genetic relationship of the germplasm resources of tea plants from Liubao town and Nandu town were fully analyzed in this study. The core molecular markers for the efficient identification of these germplasm resources were successfully screened. The main results show that: (1) 98 alleles were amplified from 17 pairs of SSR primers, and each pair of SSR primers amplified 3-8 alleles, with an average of 5.764 7 alleles per locus. (2) Totally 8 core markers were selected from 17 SSR markers to distinguish each germplasm resource. (3) The average number of alleles (4.647 1), genotypes per marker (7.000 0), genetic diversity (0.675 4), and the polymorphic information content (0.628 3) of native tea trees in Liubao town were higher than wild tea trees in Nandu, and close to the cultivated population. (4) Cluster analysis shows that the majority germplasm resources from Liubao town were clustered together except for several tea plants grouped with large-leaf tea cultivars from Yunnan province and a few resources were grouped into the same cluster with tea cultivars from Zhejiang and Guizhou provinces. The wild tea germplasm resources from Nandu town were grouped into the same cluster with two germplasm materials from Liubao town. In conclusion, it was showed that there are rich tea germplasm resources with high genetic diversity in Wuzhou city. This study might lay a solid foundation for the further studies to develop and utilize these tea resources.

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Effects of Air Conditions Preset for Withering on Flavor Quality and Chemical Profiles of White Teas

ZHANG Yinggen, XIANG Lihui, CHEN Lin, LIN Qingxia, SONG Zhenshuo, WANG Lili

Journal of Tea Science 2022, 42 (4): 525-536. DOI: 10.13305/j.cnki.jts.2022.04.011

Abstract （379）

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To realize the quality control of white tea based on withering environment, indoor temperature and relative humidity were preset at (30±2)℃ with RH (35±5)% or (20±2)℃ with RH (55±5)% to investigate the effects of four different air conditions on the sensory quality and chemical profiles of 6 tea cultivars (Camellia sinensis), including Fuan-dabaicha, Huangdan, Huangguanyin, etc. According to whether the indoor temperature and relative humidity were mutually switched at the point when the weight loss rate of tea shoots reached 45% during the whole withering procedure, the levels of each withering treatment were named as Low-Low, Low-High, High-Low and High-High, respectively. The results show that the flavor quality of white tea was mainly determined by the physical and chemical characteristics of raw materials (tea cultivars). White teas obtained under Low-Low treatment had a slightly light taste and a little grassy flavor, while the white teas from the same tea cultivars had the similar quality characteristics in appearance and soup color when they were treated with High-High and Low-High, just as High-Low and Low-Low during withering. The ultraviolet and near-infrared spectra of all white tea samples had similar fluctuations, and the near-infrared spectra could provide more abundant chemical information for their pattern recognition. The contents of gallic acid, epicatechin gallate, gallocatechin, caffeine and theobromine in white tea samples were different among tea cultivars, but withering treatment had no significant effect on the contents of detected biochemical components (catechins and purine alkaloids). Moreover, principal component analysis based on ultraviolet spectra, especially near-infrared spectra or biochemical compositions of white tea samples could better discriminate white tea samples into the same groups according to their raw materials (tea cultivars). The effects of different air conditions on the profiles of spectra or biochemical compositions were exclusively drowned by the characteristics of raw materials. However, the influence of withering treatment on the profiles of near-infrared spectra and biochemical compositions of white tea samples manufactured from different raw materials could be effectively revealed by multilevel principal component analysis, and the classification and identification results of all white tea samples were almost consistent with the characteristics of sensory quality. These facts could provide a reference for the technological regulation of white tea flavor quality.

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The Antifungal Effect and Mechanism of Berberine on Different Colletotrichum Species Causing Tea Brown Blight Disease

ZHANG Zhipeng, CHENG Qinghua, XIE Jingkang, WAN Yuhe, TONG Huarong, CHEN Yingjuan

Journal of Tea Science 2022, 42 (3): 367-375. DOI: 10.13305/j.cnki.jts.2022.03.006

Abstract （368）

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To explore the application prospects of berberine on the prevention and control of tea diseases, the antifungal activity of berberine against five different Colletotrichum species (C. fioriniae, C. karstii, C. chongqinggense, C. camelliae and C. gloeosporioides) were studied and the differences in antifungal activities were compared. The results show that berberine has the best inhibitory effect on both C. camelliae and C. chongqinggense, reaching 100% at the concentration of 12 mg·mL^-1, followed by C. gloeosporioides, C. karstii and C. fioriniae. The EC₅₀ (Concentration for 50% of maximal effect) of the five Colletotrichum species were 2.828, 3.288, 4.164, 4.778 mg·mL^-1 and 5.104 mg·mL^-1, respectively. The conidial and hyphal morphology of five Colletotrichum species under the treatment of berberine were examined, showing that berberine had a significant impact on the mycelial and conidial growth of five Colletotrichum species. With the increase of berberine concentration, part of hyphae expanded irregularly and the conidia grew abnormally. Results of the biological activity of Colletotrichum species show that the cell structure was damaged, the permeability of cell membrane was increased and the cell oxidative stress response was enhanced. Results of this study firstly confirm the antifungal activity and application prospects of berberine against Colletotrichum species, which provided a new approach and theoretical basis for the prevention and control of tea disease caused by Colletotrichum.

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Effect of Temperature-controlled Pile-fermentation on Aroma Quality of Primary Dark Tea

CHEN Hui, YANG Liling, CHEN Jinhua, HUANG Jian'an, GONG Yushun, LI Shi

Journal of Tea Science 2022, 42 (5): 717-730. DOI: 10.13305/j.cnki.jts.20220830.001

Abstract （356）

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Sensory quality evaluation of the primary dark tea under traditional, 45℃, 50℃ controlled pile-fermentation was performed. Meanwhile, volatile components were compared and analyzed by headspace solid phase microextraction and gas chromatography-mass spectrometry (HS-SPME-GC-MS) combined with principal component analysis (PCA) and partial least-squares discrimination analysis (PLS-DA). The results show that compared with traditional and 50℃-controlled pile-fermentation, the primary dark tea under 45℃-controlled pile-fermentation presented better aroma pleasure, purity and concentration. Furthermore, it appeared less impurity odor. A total of 24 key different volatile components were obtained from traditional and temperature-controlled pile-fermentation. The relative contents of α-cedrene, neophytadiene, olivetol, δ-cadinol, carvacrol, 2,6-di-tert-butyl-p-cresol, (Z)-7-hexadecenal, trans-β-ionone were significantly higher under the temperature-controlled pile-fermentation than those under traditional pile-fermentation. The research results could provide basis and reference for improving aroma quality of primary dark tea.

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Effects of Tea Polyphenols on Agrobacterium-mediated Plant Genetic Transformation System

LI Jing, LIN Cairong, HUANG Yan, DENG Xuming, WANG Yiqing, SUN Weijang

Journal of Tea Science 2022, 42 (4): 477-490. DOI: 10.13305/j.cnki.jts.2022.04.003

Abstract （352）

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In order to study the effect of tea polyphenols on the infection efficiency of Agrobacterium in tea plant genetic system mediated by Agrobacterium tumefaciens, four Agrobacterium strains LBA4404, EHA105, ATCC15834 and K599 were used as research objects. The phenolic resistance, membrane integrity, adsorption, vir gene and chv gene expression and genetic transformation of Agrobacterium tumefaciens under different concentrations of tea polyphenols were analyzed. The results show that: (1) the phenolic resistance of the four strains followed the order of LBA4404>K599>EHA105>ATCC15834, and EHA105 and ATCC15834 were more sensitive to tea polyphenols. (2) The ratio of ATCC15834 with intact membrane was negatively correlated with the concentration of tea polyphenols and the standing time, and the lowest intact membrane rate of EHA105 appeared 48 h after treatment with 600 mg·L^-1 tea polyphenols. (3) The adsorption capacities of ATCC15834 and EHA105 on tobacco mesophyll cells decreased with the increase of tea polyphenol concentrations. After treatment with tea polyphenols for 24 h, the expressions of chvB and chvB2 in ATCC15834 and EHA105 were significantly inhibited. The expression of virA was positively correlated with the sensitivity to low concentration phenols. (4) After infecting tobacco by the Agrobacterium tumefaciens solution (containing tea polyphenols), the transient and stable transformation efficiencies were inhibited to varying degrees, and the induction rate of hairy roots was greatly reduced. When the concentration of tea polyphenols was 1 000 mg·L^-1, ATCC15834 achieved the lowest root induction rate of 13.85% and the highest necrosis rate of 33.85%. In conclusion, tea polyphenols could reduce the activity and membrane integrity rate of Agrobacterium tumefaciens, and reduce the expression of chv gene to affect its adsorption, which finally suppress the instantaneous conversion efficiency and the stable conversion efficiency in tobacco conversion system to varying degrees.

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Study on the Application of Three-dimensional Vial Fermentation Technology of Puer Tea

TIAN Haixia, WEI Zhenzhen, MA Yue, LI Song, DAI Shen, LIU Haixin, HAO Binxiu

Journal of Tea Science 2022, 42 (4): 577-587. DOI: 10.13305/j.cnki.jts.2022.04.006

Abstract （344）

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In order to improve the clean processing conditions and the automatic level of post-fermented Puer tea, three-dimensional vial fermentation technology (TVFT) was developed. Using this technology, the traditional large batch of fermentation materials was divided into independent small units, packaged in vials. Equipped with automatic control system, loading, fermentation and discharging were completed by assembly line, without turning over the pile and replenishing water in the fermentation process, fermentation temperature and humidity were accurately controlled, the problems of low level of traditional pile fermentation production equipment and poor environmental controllability were solved. The level of automatic fermentation of Puer tea was also improved. The results show that the Puer tea produced by TVFT met the national standards, and automatic fermentation on a large scale was feasible. Compared with traditional fermentation process, using new technologies, the production capacity per unit area was increased by 40%, the fermentation duration was shortened by 15-20 d, and the labor cost was reduced by 75%. Twisted appearance of tea leaves was more complete. The contents of tea polyphenols, theabrownin, amino acid nitrogen and pH value were significantly increased. The stability of product quality has been improved.

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Expression Analysis and Functional Identification of CsTT2 R2R3-MYB Transcription Factor in Tea Plants

WANG Yuyuan, LIU Renjian, LIU Shaoqun, SHU Canwei, SUN Binmei, ZHENG Peng

Journal of Tea Science 2022, 42 (4): 463-476. DOI: 10.13305/j.cnki.jts.2022.04.005

Abstract （338）

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Catechin is one of the most characteristic secondary metabolites in tea plants and the main component affecting tea quality and flavor. It possessesrich pharmacological effects, such as anti-oxidation, anti-virus, lipid lowering and weight loss, etc. In this study, the function of a catechin biosynthetic regulator CsTT2 was preliminarily identified using phylogenetic analysis, gene expression pattern analysis and molecular biology experiments. The results show that CsTT2 was a R2R3-MYB transcription factor that shares a branch withthe MYB transcription factor in Arabidopsis thaliana that regulates secondary metabolites. The expression levels of CsTT2 and catechin biosynthesis genes were relatively high in the apical bud tissue of tea plants with higher total catechin content. The results of subcellular localization, yeast assay and dual luciferase reporting system further reveal that CsTT2 was located into the nucleus and the protein it encodes possessed transcriptional activation capacity. CsTT2 could bind to the promoter of a key catechin biosynthetic gene ANR to activate its expression.

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Study on the Preference of Large Yellow Tea Based on Consumers with Different Ages

AN Qi, QIU Tong, ZHANG Ying, XIAO Mingji, CHEN Aini, SHENG Caiyan, DAI Qianying

Journal of Tea Science 2022, 42 (3): 435-446. DOI: 10.13305/j.cnki.jts.2022.03.004

Abstract （337）

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In this paper, 9-point hedonic scale and 5-point just about right were used to test the preference of large yellow tea and evaluate the acceptance of sensory attributes among consumers with different ages. The results show that young and middle-aged consumers prefer low-roasted and high-tenderness large yellow tea with sweet and mellow flavors while older consumers prefer high-roasted and low-tenderness large yellow tea with the burnt, bitter and paste flavors. Combined the JAR data with the preference data through penalty analysis, the most influential attributes, the direction of attribute optimization and the order of improvement priority were qualitatively obtained from the three age groups, which was of certain reference to design and process large yellow tea products.

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Predation of Plexippus setipes on Ectropis grisescens Larvae

WANG Weitong, ZHOU Xiaogui, ZHANG Xinxin, WANG Zhibo, ZHANG Dayu, XIAO Qiang

Journal of Tea Science 2022, 42 (4): 515-524. DOI: 10.13305/j.cnki.jts.2022.04.002

Abstract （336）

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To clarify the control potential of Plexippus setipes on Ectropis grisescens, studies about the predator functional response, predation selectivity and intraspecific competition of P. setipes on E. grisescens larvae were conducted under indoor conditions. The results show that the P. setipes preferred to feed on the early stage larvae of the E. grisescens. There were significant differences in the predation ability among different developmental stages of P. setipes. Specifically, the adult spider had the strongest predation ability to hunt 17.44 larvae per day of the first instar of the E. grisescens, while the juvenile spider had relatively weak predation ability with only a daily of 2.33 larvae of the first instar. The predator functional response of P. setipes was in accordance with the Holling Ⅱ model. The Searching efficiency of P. setipes decreased with the increase of E. grisescens population. The predation selectivity shows that P. setipes showed positive preference (Ci > 0) for 1^st and 2^nd instar E. grisescens larvae along with negative preference (Ci < 0) for 3^rd instar larvae. The predatory effect of P. setipes on E. grisescens larvae was also influenced by their own population density. There was a strong intraspecific competition, which was consistent with the Hasse Ⅱ model. This study indicates that P. setipes had a strong predatory ability and control potential on E. grisescens larvae, providing a theoretical basis for exploring the use of spiders in tea plantations.

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Comparative Study on the Physicochemical Characteristics and Antioxidant Activities of Polysaccharides in Different Tea Cultivars

CHEN Xue, ZUO Xinxin, XU An'an, XU Ping, WANG Yuefei

Journal of Tea Science 2022, 42 (6): 806-818. DOI: 10.13305/j.cnki.jts.2022.06.011

Abstract （328）

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In the present work, 10 representative tea cultivars (Huangjingui, Tieguanyin, Qimenzhong, Liubaocha, Dahongpao, Zhuyeqi, Longjing 43, Baiyeyihao, Zhonghuangyihao and Fudingdabai) in the same tea garden were selected and their fresh leaves were dried directly by microwave. Tea polysaccharides (TPS) from the 10 cultivars were prepared by water extraction. Their physical and chemical characteristics were compared and analyzed by chemical analysis, high performance liquid chromatography (HPLC), infrared spectroscopy (IR), gel chromatography, scanning electron microscope (SEM), particle size measurement and Zeta potential analysis. And their antioxidant abilities including DPPH radical scavenging ability, ABTS radical scavenging ability and ferric ion reducing ability were determined as well. It was found that TPS was a kind of water-soluble acid glycoprotein, which mainly consisted of uronic acid, neutral sugar, protein and polyphenols. Meanwhile, the monosaccharide components of the 10 TPSs were mainly composed of galacturonic acid, glucose, galactose and arabinose. Principal component analysis (PCA) shows that the basic composition of TPS in Baiyeyihao and Longjing 43 were significantly different from other tea cultivars. Furthermore, the antioxidant activity of TPS in Baiyeyihao was the strongest among the obtained TPS. Correlation analysis indicates that the antioxidant capacity of TPS might be related to the contents of polyphenols and proteins.

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Effect of Pile-up Processing Duration on Flavor Quality of White Tea

WU Shaoling, WANG Zhihui, SHANG Hu, ZHU Chensong, YE Tingting, SUN Weijiang

Journal of Tea Science 2023, 43 (1): 78-90. DOI: 10.13305/j.cnki.jts.2023.01.006

Abstract （327）

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The effects of different pile up durations on the flavor quality of white tea were investigated based on sensory evaluation and biochemical analysis, in which the white tea with different pile-up processing durations were used as the experimental materials. The results of biochemical analysis show that with the increase of the pile-up processing duration, the flavor of the bitterness and astringency first weakened and then strengthened, the sweetness first increased and then decreased, and mellow gradually increased. In addition, and the sweet and floral increased. The contents of tea polyphenols, flavonoids, soluble sugar, catechins, free amino acids were the main reasons for the taste difference. The contents of cis-linalool oxide (furanoid), trans-linalool oxide (furanoid), α-terpineol, decanal, β-cyclocitral, geranylacetone, β-ionone and octanal were the key factors affecting the difference of aroma. Under different pile-up processing durations, piling-up for 12 d had the best flavor quality, which was conducive to increasing the contents of free amino acids, soluble sugar and catechins, while decreasing the bitter taste index, and increasing the contents of trans-linalool oxide (furanoid), decanal, β-cyclocitral, geranylacetone, β-ionone, promoted floral and sweet fragrance of white tea. Our study provided reference for the optimization of white tea pile-up process and the improvement of flavor quality of white tea.

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Isolation, Identification and Characterization of Aluminum-tolerant Growth-promoting Endophytic Bacteria in Tea Roots

WU Jing, CHEN Nannan, HAN Menglin, CHEN Gao, LI Weiwei, ZHANG Shuxiang, JIANG Xiaolan

Journal of Tea Science 2022, 42 (5): 610-622. DOI: 10.13305/j.cnki.jts.2022.05.006

Abstract （325）

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Tea plants are aluminum-tolerant plants. Low concentration of aluminum promotes the growth of tea plants, but its regulation mechanism remains unclear. In this experiment, 38 strains of culturable endophytic bacteria were isolated and identified from the roots of tea plants treated with aluminum, including 27 strains of Firmicutes and 11 strains of Actinomycetes. Plant growth promoting abilities of the isolated endophytic bacteria were explored from ACC deaminase, phosphate solubilization, siderophore and IAA production. It was found that the comprehensive plant growth promoting abilities of Firmicutes FBA, FPC and Actinomycetes AMM, ACP032155 were better. The relative activities of the 38 strains at different aluminum ion concentrations were further investigated. The results show that the 38 strains of endophytic bacteria could survive under 1 mmol·L^-1 Al^{3 +} concentration, among which Actinomycetes AME2 could still survive under 8 mmol·L^-1Al³⁺, which showed the strongest aluminum tolerance. The results show that aluminum treatment could promote the growth of aluminum-tolerant bacteria in tea plants, thus indirectly promoting the growth of tea plants. This study laid a foundation for the cultivation and breeding of endophytic bacteria of tea plants with significant aluminum tolerance and growth promotion ability.

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Genetic Diversity of Mature Leaves of Tea Germplasms Based on Image Features

CHEN Qiyu, MA Jianqiang, CHEN Jiedan, CHEN Liang

Journal of Tea Science 2022, 42 (5): 649-660. DOI: 10.13305/j.cnki.jts.2022.05.002

Abstract （319）

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The genetic diversity of tea germplasm in China is an important basis for its effective utilization. In this study, the genetic diversity of tea germplasm in China was elucidated by statistical analysis, principal component analysis, correlation analysis and cluster analysis of 18 image features of mature leaves from 504 tea germplasm accessions preserved in China National Germplasm Hangzhou Tea Repository. The results show that the coefficient of variation and genetic diversity index of this population were 15.97% and 1.98, respectively. Among different provinces, the average coefficient of variation was the largest in Fujian province, which was 16.29%. The data of Jiangsu province was on the bottom, accounting for 10.58%. Zhejiang province had the highest average genetic diversity index at 2.01. The average genetic diversity index of Chongqing municipality reached the lowest point, occupying 1.67. The dimension of 18 image features were streamlined by principal component analysis and characterized into 4 principal components, with a cumulative contribution rate of 82.63%, and 12 image features were screened out from 18 image features with significant differences. According to the image features, the tea germplasms were clustered into 6 groups. The results provided a theoretical basis and reference for further exploration and utilization of tea germplasm in China.

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Development of Amplitude Adjustable Imitation Manual Rocking Green Device for Oolong Tea and Research of Process Parameters

BIAN Xianbing, WU Min, JIA Jiangming, DONG Chunwang, ZHANG Chen'an, ZHAO Runmao, CHEN Jianneng, WANG Jinshuang

Journal of Tea Science 2022, 42 (3): 409-422. DOI: 10.13305/j.cnki.jts.2022.03.005

Abstract （316）

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To better promote the large-scale standardized processing of oolong tea, improve the rocking green quality and machinery efficiency, and extend the application scope of equipment, an amplitude adjustable imitation manual rocking green device and a single input multi output power transmission mechanism were designed. The kinematics analysis model of the amplitude adjustable rocking green mechanism was established, and the spatial motion trajectory of the spherical screen was simulated by MATLAB. On this basis, a rocking green prototype was developed to carry out the multi index orthogonal test of 2 factors and 4 levels of the rocking green. Then, the multi index was transformed into a single index by comprehensive scoring method, and the best process parameters were btained by the orthogonal test analysis. Under the optimal process parameters, the moderate rate of oolong tea rocking green was 84.10%, the water loss rate was 33.63%, and the comprehensive score was 97.75% of the traditional manual rocking green. The experimental results show that the developed amplitude adjustable imitation manual rocking green mechanism is effective. On the basis of matching the relevant process parameters, it can be applied to the large-scale mechanical rocking green of fresh leaves in different tenderness and seasons. Meanwhile, it also provided a new reference method for the research of relevant process parameters in the field of tea processing.

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Residue Determination of Sixteen Pesticides in Green Tea by UPLC-MS/MS

LI Ziqiang, YANG Mei, ZHANG Xinzhong, LUO Fengjian, ZHOU Li, LOU Zhengyun, SUN Hezhi, WANG Xinru, CHEN Zongmao

Journal of Tea Science 2022, 42 (4): 537-548. DOI: 10.13305/j.cnki.jts.20220416.004

Abstract （313）

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An analytical method was developed for the simultaneous determination of 16 pesticide residues in green tea by ultra-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS). The target pesticides in tea samples were extracted by acetonitrile with 1% formic acid, cleaned up by a TPT-SPE column, ionized in electrospray positive ionization source (ESI⁺) mode, and scanned for determination of the target parent and daughter ions by mass spectrometry in multiple reaction monitoring mode (MRM). The results show that the target pesticides were linear in the range of 0.005-1.000 mg·kg^-1 with the correlation coefficient R²>0.992 6. The average recoveries ranged from 74.0% to 105.4% at the four spiked levels of 0.010, 0.050, 0.100、1.000 mg·kg^-1, and the relative standard deviations (RSD) were <20.0%. The limits of quantification were 10-50 μg·kg^-1. The method is fast and sensitive, and the technical parameters are in accordance with the relevant domestic and international regulations and standards. And it can meet the requirements of simultaneous determination of various pesticide residues in green tea.

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Root Growth and Organic Acid Secretion of Tea Plants Affected by Phosphorus and Aluminum Interaction

ZHOU Beini, MEI Huiling, LI Jianjie, CHEN Lingli, ZHONG Qing, LI Xiaoqian, CHEN Xuan, LI Xinghui

Journal of Tea Science 2022, 42 (6): 819-827. DOI: 10.13305/j.cnki.jts.2022.06.006

Abstract （307）

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To investigate the effects of phosphorus-aluminum interaction on the growth of tea plants, phosphorus and aluminum interaction treatments with three aluminum concentrations and five phosphorus concentrations were set to analyze the changes in root growth, secretion of organic acids and uptake of phosphorus and aluminum in tea plants. The results show that both low phosphorus (0.01 mmol∙L^-1) and high aluminum (1 mmol∙L^-1) significantly promoted the growth of new roots in tea plants, and the number of root tips, root length, average diameter and increase of dry matter in new roots reached the maximum under the combined treatment of low phosphorus and high aluminum. High aluminum was able to restore the growth of new roots impeded by high phosphorus (0.5 mmol∙L^-1) conditions. In addition to the high phosphorus treatment (0.5 mmol∙L^-1), increasing the concentration of phosphorus or aluminum in the environment could significantly promote their accumulation in the roots of tea plants. Within a certain range, phosphorus significantly promoted the accumulation of aluminum in shoots. However, aluminum inhibited the accumulation of phosphorus in shoots when phosphorus was sufficient (>0.05 mmol∙L^-1). When phosphorus was sufficient, high aluminum promoted the secretion of oxalic acid, malic acid and citric acid. Phosphorus application promoted the secretion of citric acid, while low phosphorus promoted the secretion of oxalic acid and malic acid. Low phosphorus and high aluminum synergistically promoted the secretion of malic acid. The results of two-way ANOVA show that phosphorus and aluminum concentrations and their interaction had highly significant effects on root length, root tip number, phosphorus and aluminum uptake and organic acid secretion in tea plants (p<0.01), which showed that phosphorus and aluminum interaction can affect root growth and organic acid secretion of tea plants significantly.

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Screening of Tea Germplasm Resistant to Matsumurasca onukii and Dendrothrips minowai Priesner and Analysis of Resistance-related Factors

SUN Yue, WU Jun, WEI Chaoling, LIU Mengyue, GAO Chenxi, ZHANG Lingzhi, CAO Shixian, YU Shuntian, JIN Shan, SUN Weijiang

Journal of Tea Science 2022, 42 (5): 689-704. DOI: 10.13305/j.cnki.jts.2022.05.007

Abstract （304）

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The resistance of different tea cultivars against Matsumurasca onukii and Dendrothrips minowai Priesner was explored to provide a scientific basis for the breeding and promotion of insect resistant tea cultivars. Taking 11 tea cultivars (Zijuan, Shuixian, Meizhan, Baijiguan, Ruixiang, Qilan, Huangguanyin, Baimudan, Huangyuanyin, Dahongpao and Huangguanyin) as the test materials, the field population was investigated by five-point sampling method. Through investigation of field population density and tea plant morphological characteristics, determination of leaf tissue structure and detection of chemical composition, the relationship among physical properties, chemical components and insect resistance of tea plants was analyzed. The results show that 11 tea cultivars could be divided into 4 categories according to their resistance to M. onukii. category Ⅰ: Zijuan, insect-susceptible (S), category Ⅱ: Meizhan, Huangdan, Qilan, Shuixian, Baimudan, middle susceptible (MS), category Ⅲ: Ruixiang, Dahongpao, Huang guanyin, Huangmeigui, middle resistant (MR), category Ⅳ: Baijiguan, resistant (R). According to the strength of resistance to D. minowai Priesner, it can also be divided into 4 categories, category Ⅰ: Huangmeigui, insect-susceptible (S), category Ⅱ: Ruixiang, Baijiguan, moderate sensitivity (MS), category Ⅲ: Huang Guanyin, Qilan, middle resistant (MR), category Ⅳ: Baimudan, Huangdan, Dahongpao, Meizhan, Zijuan, Shuixian, resistant (R). Combined with correlation analysis, the total number of M. onukii was highly significantly and positively correlated with the anthocyanin content and GCG content of 11 tea cultivars (P<0.01), and significantly and positively correlated with upper cuticle thickness/leaf thickness and lower cuticle thickness/leaf thickness (P<0.05). However, it was significantly and negatively correlated with free amino acids, palisade tissue thickness, upper epidermis thickness and upper epidermis thickness/leaf thickness (P<0.05). There was a significantly negative correlation between leaf length and the total number of D. minowai Priesner (P<0.05), and the total number of M. onukii was significantly and negatively correlated with the total number of D. minowai Priesner (P<0.05). After comprehensive evaluation, the tea cultivars of Dahongpao and Huangguanyin have certain resistance to M. onukii and D. minowai Priesner, which are worthy of promotion. Meanwhile, there was a phenomenon that M. onukii and D. minowai Priesner alternately damage the tea plants in the same period.

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Genetic Diversity Analysis of Tea Genetic Resources in Sanjiang, Guangxi

MENG Rongjun, CHEN Liang, XU Yuan, LIN Wei, ZHOU Qiwei, XIE Yilin, LAI Dingqing, LAI Jiaye

Journal of Tea Science 2023, 43 (2): 147-158. DOI: 10.13305/j.cnki.jts.2023.02.009

Abstract （302）

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In order to clarify the genetic diversity of tea genetic resources in Sanjiang, Guangxi, two marker techniques, simple inter-repeat sequence amplification (ISSR) and correlated sequence amplification polymorphism (SRAP) were used to analyze the genetic diversity of 72 local tea genetic resources and five introduced cultivars in Sanjiang region. The results of both marker techniques show high levels of genetic diversity (H=0.30, I=0.44), high genetic differentiation between populations (Gst=0.056) and gene flow (Nm=8.64). The genetic variation observed within populations was much higher than that between populations. The cluster analysis shows that most of the tea genetic resources in Sanjiang were clustered into one group and the introduced cultivars were clustered into the other, which was consistent with the results of PCoA. This study provided evidence at the molecular level for the protection and utilization of tea germplasmin Sanjiang.

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Research and Application of Intelligent Identification of Empoasca onukii Based on Machine Vision

BIAN Lei, HE Xudong, JI Huihua, CAI Xiaoming, LUO Zongxiu, CHEN Huacai, CHEN Zongmao

Journal of Tea Science 2022, 42 (3): 376-386. DOI: 10.13305/j.cnki.jts.20220506.001

Abstract （297）

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Deep learning has been widely used in intelligent identification in the progress of real-time monitoring of crop pests. Based on the identification model of tea leafhopper, Empoasca onukii, the application of deep learning in field leafhopper recognition was introduced to improve the precision of field population investigation of E. onukii. In this paper, a method of identification and count of E. onukii in tea garden was designed. Firstly, yellow sticky card was used to attract tea leafhoppers, and images of cards were collected by camera and uploaded to the web server. Then, target detection algorithm deployed by the server was used to identify and count the leafhoppers in the images. Through algorithm screening, YOLOv3 was determined as the recognition algorithm, and the improved soft-NMS was used to replace the original NMS. K-means clustering method was used to calculate the size of the new prior frame, so as to improve the speed and precision of YOLOv3. The results show that the average precision of the optimized algorithm could reach more than 95.35% comparing with the real number of leafhoppers on the sticky card. Therefore, the combination of the sticky card trapping, target recognition algorithm and internet of things technology could realize the real-time monitoring of population for E. onukii, which could provide a reference for other insects with color preference and integrated pest management in tea gardens.

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