Journal of Tea Science

Physiological and Molecular Mechanisms of Transmembrane Fluoride Uptake by Tea Roots

XU Jiajia, GUANG Min, SHI Shulin, GAO Hongjian

Journal of Tea Science. 2019, 39(4): 365-371. doi:10.13305/j.cnki.jts.2019.04.001

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Tea plant is a fluoride hyper-accumulator and most of fluoride is accumulated in the leaves. Drinking tea is an important way to absorb fluoride for human, which affects human health. Fluoride is usually absorbed from the soil by tea roots. However, the physiological and molecular mechanisms of transmembrane fluoride uptake by the tea roots were still poorly documented. Therefore, this paper reviewed the active and passive pathways of fluoride uptake by the roots of tea. The active transmembrane uptake fluoride process and molecular mechanism by H⁺-ATPase and Ca²⁺-ATPase, the role and microscopic process of ion channel and Al-F complexation by passive fluoride uptake were analyzed. The main influencing factors and control measures of fluoride accumulation in tea roots were also investigated. In order to reveal the molecular mechanism of transmembrane fluoride uptake, regulate the selective fluoride uptake in tea roots, and ensure the tea quality and safety for consumption, cloning, expression, and functional verification of transport proteins and genes related to fluoride transmembrane uptake in tea plant should receive more attention in future studies.

Perchlorate Contamination in Tea and Its Analytical Techniques

DENG Jiajun, PAN Hua, ZHANG Fusheng, ZHANG Li, CAO Fang, ZHANG Zhifang, CHEN Junsong

Journal of Tea Science. 2019, 39(4): 372-381. doi:10.13305/j.cnki.jts.2019.04.002

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Perchlorate in tea, as an emerging contaminant, poses a potential risk for food safety, human health and foreign trade, which has raised increasing concerns over the contamination of tea with perchlorate. In this paper, pollution sources, status and the main causes of pollution in tea of perchlorate were described. The analytical techniques of perchlorate in tea samples were also summarized. These data would provide references for studies of environmental transport behaviors, agri-food safety, human health risk and relevant standards of security in China.

Functional Analysis of Glutathione Peroxidase Encoding Gene CsGPX1 in Camellia sinensis

LIU Sai, LIU Shuoqian, LONG Jinhua, WU Dunchao, CHEN Yuhong, LIU Liping, LIU Zhonghua, TIAN Na

Journal of Tea Science. 2019, 39(4): 382-391. doi:10.13305/j.cnki.jts.2019.04.003

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To clarify function of glutathione peroxidase-encoding gene CsGPX1 in Camellia sinensis (L.) O. Kuntze, the full-length sequence of the coding region of CsGPX1 was obtained by transcriptome data of tea plant, and sequence analysis and function prediction were performed. Then, the CsGPX1 was overexpressed in tobacco. Subsequently, the difference in drought tolerance between wild-type and transgenic tobacco was compared to verify the function of CsGPX1. Sequence analysis indicates that CsGPX1 was 723 bp in length, encoding 240 amino acids. The Blast alignment reveals that the GPX showed more than 85% of identity in amino acid with GPX from Prunus persica. The amino acid sequence encoded by CsGPX1 has a conserved characteristic sequence of the GPX protein and a phospholipid hydrogen glutathione peroxidase (PHGPX) which is unique to other family members. The results of drought stress treatment show that the drought resistance of the over-expressing of CsGPX1 in tobacco lines was stronger than that of wild-type. The results of GPX enzyme activity assay show that the GPX enzyme activity of the transgenic plants was higher than that of the wild type plants. All of above results verify that the over-expression of CsGPX1 improved the drought tolerance of transgenic tobacco, suggesting that CsGPX1 might be related to the drought resistance in tea plants. This study could provide a new strategy to improve the drought resistance of tea plants, which would significantly reduce the management cost of tea plantation.

Genome-wide Identification and Expression Analysis of SRO Gene Family in Camellia sinensis

GUO Yongchun, WANG Pengjie, CHEN Di, ZHENG Yucheng, CHEN Xuejin, YE Naixing

Journal of Tea Science. 2019, 39(4): 392-402. doi:10.13305/j.cnki.jts.2019.04.004

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SROs (Similar to rcd one) are plant-specific gene families. In this study, 9 CsSRO gene family members were identified from tea tree genome by bioinformatics method and named as CsRCD1—4 and CsSRO1—5 respectively. All coding proteins of the 9 CsSRO genes have characteristic structural domains PARP and RST, and have similar conserved motifs. The CsSRO genes were divided into 3 groups based on phylogenetic tree analysis, with the group Ι containing CsRCD1—4, the group Ⅱ containing CsSRO1, CsSRO2 and the group Ⅲ containing CsSRO3—5. Gene structure analysis shows that this gene family contained 4 to 9 exons. Analysis of transcriptome data from 8 tea tree tissues shows that CsRCD1/CsRCD3/CsRCD4 might play an important role in different developmental stages of tea plants. Most CsSRO genes were highly expressed in roots and mature leaves. Upstream promoter region analysis found a large number of cis-acting elements closely related to plant development, hormones and stress response. Further expression analysis shows that 9 CsSRO genes were induced by drought and abscission acid treatments, suggesting CsSRO genes may be closely related to drought resistance.

Effects of Green, Black and Fu Brick Tea Aqueous Extracts on the Characteristics of Intestinal Microbiota during in vitro Fermentation

HOU Aixiang, YAN Daomin, SUN Jingwen, ZHENG Xu, LI Saidan, XIAO Runhua, BEI Shuang

Journal of Tea Science. 2019, 39(4): 403-414. doi:10.13305/j.cnki.jts.2019.04.005

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In order to demonstrate the interaction effect of different tea aqueous extracts and intestinal microorganisms, anaerobic fermentation in vitro by the intestinal bacteria from healthy college students’ feces were conducted in this study. Traditional culture techniques and gas chromatography technology were employed to study the changes of pH, short-chain fatty acids and intestinal microbes in different tea aqueous extracts (green, black and Fu brick tea) during 24 h of in vitro fermentation, and calculate the prebiotic index PI and B/E values (Bifidobacterium/Enterobacterium). The results show that the tea aqueous extracts significantly decreased the pH value compared with the blank control group, and the biggest drop was identified in the Fu brick tea group. Besides, the tea aqueous extracts significantly increased the production of short-chain fatty acids. Green tea had the largest increase in acetic acid, propionic acid, isobutyric acid, iso-pentanoic acid, pentanoic acid and total short-chain fatty acids, while Fu brick tea had the largest increase in butyric acid. All three kinds of tea aqueous extracts could affect the composition of intestinal microorganisms, promoted the growth of Bifidobacterium and inhibited the growth of Bacteroides, Enterobacterium and clostridium. Fu brick tea group had the largest promoting effect on Bifidobacterium, had the most obvious inhibiting effect on Enterobacterium and clostridium, and green tea group had the largest inhibiting effect on Bacteroides. However, both green and black tea groups could promote the growth of Lactobacillus, while Fu brick tea group showed inhibition of Lactobacillus growth. In addition, by analyzing PI value and B/E value, It was found that green, black and Fu brick teas had the function as probiotics. The largest PI value at the 4 h stage appeared in fu brick tea, while the largest PI value at the 8 h, 12 h and 24 h stages appeared in green tea. the largest B/E value throughout the fermentation process appeared in Fu brick tea group. This study provided basic data and scientific basis for the further expansion and promotion of different teas in the youth consumption market.

Hypoglycemic Effects of Black Tea and Fungus Fermented Black Brick Tea on Hyperglycemic Model Mice

ZHOU Yang, XIAO Wenjun, LIN Ling, YUAN Dongyin, PENG Yingqi, TAN Chunbo, ZHANG Qiang, GONG Zhihua

Journal of Tea Science. 2019, 39(4): 415-424. doi:10.13305/j.cnki.jts.2019.04.006

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Based on the successfully establishment of hyperglycemia model by intraperitoneal injection of streptozotocin, 90 KM male mice were randomly divided into the normal, model, black tea treated (high, medium, low doses), fungus fermented black brick tea treated (high, medium, low doses) and metformin hydrochloride (n=10/each group) groups, and were continuously administrated for 28 days to study the hypoglycemic effects of black tea and fungus fermented black brick tea processed from the same batch of fresh leaves. The results show that compared with the normal group, the weight, water, diet and blood glucose levels of the model group were significantly different (P<0.01). The blood glucose level of the model group reached the standard of hyperglycemic index and indicates that the model was successful. Compared with the model group, the high dose of black tea treated group and fungus fermented black brick tea treated groups’ liver index were significantly decreased (P<0.05) and the pancreas index were significantly enhanced (P<0.05). The total cholesterols of the middle and high doses of black tea treated groups and fungus fermented black brick tea treated groups were significantly decreased (P<0.05), while the activities of superoxide dismutase and catalase were significantly increased (P<0.05). The blood sugar, triglyceride and malondialdehyde levels of black tea treated groups and fungus fermented black brick tea treated groups were significantly decreased in a dose-dependent manner (P<0.05). Besides, glucose tolerance, activity of glutathione peroxidase, insulin levels were increased significantly in a dose-dependent manner (P<0.05). The damaged structure of pancreas were repaired in black tea treated and fungus fermented black brick tea treated groups. Except for the low-dose black tea treated group, the hepatic glycogen level were enhanced in other black tea treated groups (P<0.05). Compared with the black tea groups, the high-dose fungus fermented black brick tea was significantly superior to the high-dose black tea in improving insulin level, blood sugar level, oral glucose tolerance, malondialdehyde level and liver glycogen level (P<0.05). The middle and high dose groups of fungus fermented black brick tea were also significantly superior to the middle and high dose groups of black tea in increasing the activities of catalase, superoxide dismutase and glutathione peroxidase. The results prompt that both the black tea and fungus fermented black brick tea could reduce the blood glucose of hyperglycemic mice, and fungus fermented black brick tea had better effects than black tea. The underlying mechanism needs further investigation.

Fungicidal Activity Comparison and Synergetic Effect of Citronellol Optical Isomers Against Colletotrichum gloeosporioides

XIANG Xiaolong, YANG Wen, LIU Huifang, CHEN Yao, ZHOU Yufeng, HU Anlong

Journal of Tea Science. 2019, 39(4): 425-430. doi:10.13305/j.cnki.jts.2019.04.007

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In this study, the activities of dextral citronellol, rhodinol and their synergistic effect to the C. gloeosporioides was determined by method of mycelial growth rate, Horsfall and co-toxicity coefficient. The EC₅₀ of dextral citronellol and rhodinol were (113.27±0.95) mg·L^-1 and (119.87±0.20) mg·L^-1 respectively. The dextral citronellol and rhodinol were mixed according to the mass ratio. The result shows that the synergistic effect was the highest with the co-toxicity coefficient of 130.19 under the mass ratio of 1.6︰1 (dextral citronellol︰rhodinol). The co-toxicity coefficients were 120.57 and 121.42 when the mass ratio were 1︰1.4 and 1︰3.8, respectively. The results indicate that citronellol and its two optical isomers had high inhibiting activities against C. gloeosporioides, and the synergistic effect could be performed by mixing them within certain proportion.

Isolation, Screening and Identification of A Strain of Trichoderma Antagonizing Tea Anthracnose

ZHAO Xingli, ZHANG Jinfeng, ZHOU Yufeng, ZHAO Dailin, ZHANG Li, ZHOU Luona, TAO Gang

Journal of Tea Science. 2019, 39(4): 431-439. doi:10.13305/j.cnki.jts.2019.04.008

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To obtain antagonistic Trichoderma for biocontrol of tea anthracnose, the twenty-three Trichoderma strains were isolated from Camellia sinensis rhizosphere-soil by taking gradient dilution. Among them, the strain LS17110205 against tea anthracnose was screened by using dual-culture and inhibition zone assay. The results show that the inhibitory rate of LS17110205 against tea anthracnose was up to 76.96% and a large number of white hyphae and green spores were produced on the colony of tea anthracnose, which caused the tea anthracnose colony to shrink and became dark. The fermentation liquid of LS17110205 was effective against pathogen hyphae, and the inhibitory rate was 70.08%. The results show that the fermentation of the strain LS17110205 caused the tea anthracnose mycelia to shrink on the surface by scanning electron microscope analysis. LS17110205 was identified as Trichoderma asperelloides on the basis of the morphological characteristics and phylogenetic tree. The results provided theoretical basis in biocontrol of tea anthracnose.

Determination of Pymetrozine in Tea Products by Solid Phase Extraction-Ultra High Performance Liquid Chromatography-Tandem Mass Spectrometry

YU Huan, ZHOU Li, LIN Qin, YANG Jie, SUN Hezhi, WU Xudong, WANG Xinru, ZHANG Xinzhong, CHEN Zongmao, LUO Fengjian

Journal of Tea Science. 2019, 39(4): 440-446. doi:10.13305/j.cnki.jts.2019.04.009

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An analytical method for the determination of pymetrozine residues in tea products, including dry tea, matcha and instant tea powder, was established based on Cleanert PCX solid phase extraction-ultra high performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS). The residual pymetrozine in dry tea, matcha and instant tea powder was extracted by a mixture of methanol and water, cleaned up and concentrated by a Cleanert PCX SPE column, and separated on an Acquity BEH C₁₈ column. Pymetrozine level was detected by UPLC-MS/MS on multiple reaction monitoring (MRM) mode and quantified with external standard method. In the spiked range of 0.005-1.000 mg·kg^-1, the average recovery of pymetrozine was 77.0%-95.1%, and the relative standard deviation (RSD, n=5) ranged from 1.8%-6.9%. The limit of quantitation (LOQ) was 0.005 to 0.010 mg·kg^-1. The sensitivity, precision and recovery of the developed method meet the requirements for residual pesticides analysis in various tea products. The results of this study can provide an analytical method for the determination and risk assessment of pymetrozine in tea products.

Different Photosynthetic Responses of Camellia sinensis to Lushan Altitude Gradient

CHENG Dongmei, ZHANG Li, WEI Hongfei, JIANG Xinfeng, ZHOU Saixia, ZHANG Zhiyong, PENG Yansong

Journal of Tea Science. 2019, 39(4): 447-454. doi:10.13305/j.cnki.jts.2019.04.010

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To illustrate the photosynthetic response and photosystem Ⅱ (PSⅡ) photoinhibition of tea leaves to altitudinal gradient, native tea population of Camellia sinensis grown in the cloudy and misty Lushan Mount was measured in terms of photosynthetic gas exchange and chlorophyll fluorescence. Results show that the leaf thickness, maximum photosynthesis rate (Pnmax), maximum relative electron transport rate of PSⅡ [rETR(Ⅱ)]max, compensation irradiation (Ic), saturation irradiation (Isat), half saturation irradiation (Ik) and water usage efficiency (WUE) increased with the altitude increased. While vapor pressure deficit (VPD), stomatal conductance, transpiration rate, intercellular CO₂ and dark respiration rate (Rd) displayed an opposite trend. The maximum potential photochemical efficiency of PSⅡ (Fv/Fm) increased while the quantum yield of non-regulated energy dissipation of PSⅡ [Y(NO)] decreased with the altitude increased. The effective photochemical quantum yield of PSⅡ [Φ(Ⅱ)], photochemical quenching (qP) and relative electron transport rate of PSⅡ [rETR(Ⅱ)] all increased at higher altitudes. Overall, tea trees at lower altitudes exhibited decrease of photosynthetic performance compared to those at higher altitudes, due to photoinhibition of PSⅡ.

Dynamics of Scent Type and Aroma Components of Wuyi Dahongpao during the Preliminary Processing

WANG Fang, ZHANG Jianming, LI Bo, CHEN Baiwen, LIU Baoshun, ZHAN Shiquan, LIU Shizhang

Journal of Tea Science. 2019, 39(4): 455-463. doi:10.13305/j.cnki.jts.2019.04.011

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The aroma components of tea leaves of Wuyi Dahongpao during the preliminary processing were investigated by headspace solid phase microextraction/gas chromatography-mass spectrometry (GC-MS). The results show that compared to the fresh leaves, the aroma component contents of alkanes, aldehydes and ketones such as nonaldehyde, tetradecane, tridecane, dodecane, butyl-2-ethyl-1,2,3-propyltriester, di-tert-dodecyl disulfide and orange blossom tert acetate were decreased drastically during the preliminary processing, which were decreased by 72.4%, 91.8% and 63.6% in the raw made tea, respectively. The alcohol, ester and olefin aroma components such as nerolidol, alpha olefin, indole, phenylacetonitrile, phenylethyl alcohol, caproic acid ester, hexanoic acid-shun 3-hexene ester, hexanoic acid-2-hexene ester and benzoic acid ester, acid-3-hexene-1-ester, and benzoic acid 2-hexene ester were largely increased during the preliminary process. The alcohol, ester and olefin aroma components involved in the characteristic flavor of Dahongpao were increased by 215.5%, 70.8% and 682.6% in the raw made tea respectively.

Study on Physicochemical Characteristics of Matcha Powder with Different Particle Sizes

ZHANG Hui, WANG Huifang, LIU Yanyan, FAN Zhengrong, ZHANG Zhengzhu, LIU Zhengquan

Journal of Tea Science. 2019, 39(4): 464-473. doi:10.13305/j.cnki.jts.2019.04.012

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Taking the physicochemical characteristics as indicators, the tea was superfine grinding by a production type ball mill to obtain Matcha with medium particle size of 117.094, 60.176, 40.041, 30.646, 25.282, 21.090, 19.199 and 14.209 µm, and to explore the physicochemical characteristics of Matcha at different particle sizes. The results show that with the pulverization time prolonged, the particle size of the powder gradually decreased and the degree of cell breakage increased remarkably. However, the functional group structure of the main component of the tea powder did not change. When the particle size was refined to a certain extent, the specific surface area and surface energy increased, the particles were in an unstable energy state, and prone to adhesion and agglomeration. The bulk density of the powder reduced, which was related to the increase of the porosity of the powder. Due to the increased specific surface area of the tea sample, the internal substances of the powder exposed, so that the water content and total water content reduced. The brightness of tea powder gradually increased, and the greenness increased. With the pulverization time prolonged, the content of tea polyphenols, free amino acids and other substances increased first and then decreased, while the contents of ascorbic acid and EGCG tended to reduce. The above results show that the superfine grinding process had a significant impact on the physicochemical characteristics of Matcha.

Study on Primitive Morpheme in Sensory Terminology and Flavor Wheel Construction of Chinese Tea

ZHANG Yingbin, LIU Xu, LU Chengyin

Journal of Tea Science. 2019, 39(4): 474-483. doi:10.13305/j.cnki.jts.20190530.001

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The critical work of perfecting sensory terms is to further set the rules for the complex terms by extracting, classifying and defining primitive morphemes. Based on the standard GB/T 14487—2017 (Terms of tea sensory tests), a total of 137 primitive morphemes were extracted, including 48 appearance and brewed leaves terms, 17 color terms, 46 aroma terms, 13 flavor terms and 13 degree terms. These primitive morphemes were also defined in English and Japanese. Through the analysis of the composition and semantics of these terms, Chinese tea color wheel, taste wheel, aroma wheel and sensory attributes wheel were constructed depending on practical tea sensory evaluation experience.

Research on Screening Rate of Fresh Tea Leaves Classifier Based on EDEM

LI Bing, LI Weining, BAI Xuanbing, ZHANG Zhengzhu

Journal of Tea Science. 2019, 39(4): 484-494. doi:10.13305/j.cnki.jts.2019.04.013

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In order to improve the screening rate of fresh tea leaves classifier, the key technical parameters of 6CFJ-70 fresh tea leaves classifier were studied with machine picking fresh leaves of willow-Leaf tea plant. Solidworks 2014 was used to build the 3D model of fresh tea leaves classifier. Based on discrete element method, the simulation granular model and contact mechanics model of fresh tea leaves were established, and the key simulation technical parameters were set up. EDEM 2018 software was used to simulate the conical drum of fresh tea leaves. The movement of the conical drum was simulated numerically, and the key parameters affecting the screening rate were the rotational speed and inclination angle of the conical drum. In order to optimize the above parameters, a quadratic rotation orthogonal combination experiment with 2 factors and 5 levels was designed with screening rate as objective function. The quadratic regression model was obtained by response surface method and the related validation tests were carried out. The results show that the main factors affecting the classification efficiency of fresh leaves are the rotational speed of conical drum and the inclination of conical drum in turn. When the rotating speed of conical drum is 24 r·min^-1 and the inclination angle of conical drum is 6 degrees, the screening rate of fresh leaves is 81.7%, which has a good effect of fresh leaves classification. The research content of this paper can provide technical reference for the design and optimization of fresh tea leaves classifier.

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