Journal of Tea Science

Innovation and Application of Control System for Pesticide Residues and Contaminants in Tea

CHEN Zongmao, LUO Fengjian, ZHOU Li, LOU Zhengyun, ZHENG Zuntao, ZHANG Xinzhong, ZHAO Ying, SUN Hezhi, YANG Mei, WANG Xinru

Journal of Tea Science. 2021, 41(1): 1-6. doi:10.13305/j.cnki.jts.2021.01.001

Abstract ( 967 )

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In the past 30 years, to solve three problems involved in quality and safety of tea, namely how to set the scientific maximum residue limits (MRLs) in tea, how to control the pesticide and contaminant residue, and how to improve detection method, the principal of “effective risk assessment” by using tea infusion was innovated. Based on that, the principal of global MRLs on tea was reconstructed. The key point in the control of pesticide residues and important contaminants was revealed, and the selection principal and application technology of pesticides were established. The in-situ and high-throughput analytical methods for pesticides and contaminants in tea were developed. The control system based on “MRLs fixation, residue control and recognition detection” was constructed and popularized. These work would promote the scientific and technological progress of the sustainable development of tea industry in China.

Inhibition of Active Compounds in Tea on Melanin Formation

WANG Wei, CHEN Lin, WANG Weiwei, ZHANG Jianyong, JIANG Heyuan

Journal of Tea Science. 2021, 41(1): 7-18. doi:10.13305/j.cnki.jts.20201209.002

Abstract ( 770 )

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Melanin is a kind of high molecular biological pigment. The color of skin is determined by the type and accumulation of melanin as well as the redistribution and degradation of melanosome. Solar ultraviolet radiation is the most common cause of melanin formation. Although melanin can protect skin cells from UV damage, the abnormal accumulation of melanin will lead to diseases related with melanin disorders. Therefore, the development of green, safe and efficient melanin inhibitors extracted from plants has become a research hotspot in recent years. Many studies have proved that extract or monomer compounds of tea could significantly inhibit (a) the activity of tyrosinase, (b) the growth, proliferation, infiltration and metastasis of melanocytes, (c) the occurrence of skin cancer. In this paper, the research progress of tea active compounds inhibiting melanin formation in acellular tyrosinase test system, cell test system, animal model and human skin was reviewed to fully explore the key active compounds, find a safe and efficient inhibitor of melanin synthesis and provide reference for the comprehensive utilization of tea products and increasing the added value of tea industry.

Advances of Magnesium Nutrition in Tea Plant

ZHANG Qunfeng, NI Kang, YI Xiaoyun, LIU Meiya, RUAN Jianyun

Journal of Tea Science. 2021, 41(1): 19-27. doi:10.13305/j.cnki.jts.20201209.001

Abstract ( 937 )

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Magnesium (Mg) is not only the central atom of chloroplast, but also participates in the biosynthesis of quality-related components (theanine) in tea plant. The impacts of Mg on tea quality and plant growth have been well established. However, Mg fertilizer is still not widely used in tea gardens of China, although Mg deficiency frequently occurs. This paper reviewed main studies of Mg nutrition in tea plant in the past 30 years, including the application of Mg nutrition in tea gardens, impact of Mg on tea quality, and interactions of Mg and other nutrients. In view of the shortage of Mg in tea garden soil, insufficient input of Mg fertilizer and unclear mechanism of Mg utilization in tea plant, prospect of research on Mg in the future were put forward.

Genome-wide Investigation and Expression Analysis of DNA Demethylase Genes in Tea Plant (Camellia Sinensis)

CHEN Yao, ZHANG Weifu, REN Hengze, XIONG Fei, ZHANG Haojie, YAO Lina, LIU ying, WANG Lu, WANG Xinchao, YANG Yajun, HAO Xinyuan

Journal of Tea Science. 2021, 41(1): 28-39. doi:10.13305/j.cnki.jts.2021.01.004

Abstract ( 634 )

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DNA demethylase (dMTase) is a bifunctional enzyme with activities of glycosylase and apyrimidic lysase during active demethylation. Based on the available genome data of tea plant, bioinformatics analysis was used to comprehensively identify DNA demethylases (CsdMTase) in tea plant. The genome-wide identification results show that the tea cultivar Shuchazao contains 4 CsdMTases. These CsdMTases could be divided into two branches (DME and ROS) with differences in gene length and intron number by phylogenetic and gene structure analysis. Further analysis shows that the physical and chemical properties of different CsdMTase proteins are similar, which contain the typical conserved domains of ENCO3c and RRM_DME and are located in the nucleus. The promoter regions of CsdMTases contain a large number of cis-acting components related to light response, plant hormone response, stress response and growth and development. The CsdMTase genes are expressed in all detected tissues with certain tissue specificity. The expressions of CsdMTases were significantly up-regulated under biotic stresses, including Colletotrichum camelliae, Pseudopestalotiopsis camelliae-sinensis and Ectropis oblique treatments. During winter dormancy, different expression patterns of CsdMTases were detected in mature leaves and overwintering buds of different cultivars. The expressions of CsDMEa and CsDMEb at different stages of flower bud development and seed germination were significantly induced. The results show that active DNA demethylation process mediated by CsdMTases plays a crucial role in regulating the stress responses, growth and development of tea plant, providing a theoretical basis for discovering the epigenetic regulation mechanism in tea plant.

Research of Theanine-related Genes Expressed in Etiolated Tea Plant (Camellia Sinensis)

JIN Ke, HUANG Jian'an, XIONG Ligui, LIU Shuoqian, QIN Xiaohong, PENG Jing, LI Yinhua, LI Juan

Journal of Tea Science. 2021, 41(1): 40-47. doi:10.13305/j.cnki.jts.2021.01.005

Abstract ( 528 )

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Etiolation is a common morphological variation in tea plants. In those mutants, the contents of the characteristic metabolites change greatly and amino acids are highly accumulated. Studying the reasons of these changes can help to reveal the relationship between leaf color variation and amino acid metabolism. In this study, an etiolated tea plant, which was found accidentally in Shimen area, was used as the research material. As a leaf-color mutant, it has three different colored leaves: yellow, green and yellow-green. The ultrastructure of the chloroplasts, the contents of characteristic metabolites, the expression levels of theanine-related genes (TS, CsGS1, CsGS2) and the correlation between the expression levels and theanine in different leaves were studied. The results show: (1) the chloroplast structure of the yellow leaves was abnormal, which mainly presented as the blurry structure of the thylakoid membrane. (2) the alkaloid contents reduced from yellow, green to yellow-green leaves with significant differences. (3) gallic acid and total catechin contents were the highest in green leaves, and there was no significant difference between the other two groups. The contents of multiple catechins increased as the leaves turned green, but the contents of EC were positively related to the etiolation. (4) the contents of amino acids and theanine increased as the leaves turned yellow. (5) TS and CsGS1 showed the highest expressions in green leaves but the lowest expressions in yellow-green leaves. While CsGS2 exhibited the highest expression in yellow leaves. (6) high theanine content was not related to the expressions of TS, CsGS1 and CsGS2. In summary, the chloroplast structure of etiolated tea plant is abnormal, the metabolism is affected, the amino acid decomposition is inhibited in the etiolated leaves, which result in the enrichment of amino acids.

Effects of Raw Materials from Different Tea Cultivars on Green Brick Tea Quality

YIN Yuxin, CHEN Yuqiong, JIAO Yuanfang, HAO Juan, YU Zhi, NI Dejiang

Journal of Tea Science. 2021, 41(1): 48-57. doi:10.13305/j.cnki.jts.2021.01.006

Abstract ( 782 )

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To explore the influence of tea leaves from different cultivars on the quality of Green brick tea, the leaves of 13 tea cultivars were used in this study. The sensory qualities of Green brick teas were evaluated according to the sensory evaluation. The main chemicals and aroma components were analyzed by chemical analysis and GC-MS method. The main components of Green brick teas made from different tea cultivars were significantly different. Among them, high contents of water extract, tea polyphenols, catechins, amino acids and soluble sugars of Green brick teas from Yingshuang, Oolong 2 and 4 were observed, but their contents in Green brick teas from Wuniuzao, Baiye 1, Fuding Dabaicha and E′cha 10 were relatively low. The latter also showed low ratio of phenol to ammonia and mellow taste. Aroma analysis shows that main aroma components were alcohols, aldehydes, ketones and alkenes, accounting for more than 85% of the total aroma. Green brick tea from Oolong 1 had the highest total aroma content and the lowest aroma similarity with other cultivars, with an outstanding aroma. Green brick tea from Oolong 4 had higher aroma similarity and better aroma coordination with other cultivars. Sensory quality analysis shows that the comprehensive qualities of Green brick teas from E′cha 10, Oolong 1 and 4 were the best, with a score of more than 88. Green brick tea from Baiye 1 had the lowest score. Green brick teas from Zhuyeqi, Echa 1 and Oolong cultivars had special fragrance. Green brick teas from oolong cultivars had the characteristics of abundant water extract, high ratio of polyphenols to amino acids, and special aroma. The Green brick teas from cultivars suitable for processing both green and black tea contained relatively high water extract and polyphenols, and good comprehensive quality. The Green brick teas from cultivars suitable for processing green tea only had mellow or neutral taste, suggesting the possibility to blending with other cultivars containing high polyphenols.

Effects of Exogenous 24-Epibrassinolide on Photosynthetic Characteristics of Tea Plants

WAN Qiwen, YANG Ni, LI Yimin, HAN Miaohua, LIN Shijia, TENG Ruimin, ZHUANG Jing

Journal of Tea Science. 2021, 41(1): 58-70. doi:10.13305/j.cnki.jts.2021.01.007

Abstract ( 511 )

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With tea plant cultivar ‘Zhongcha 108’ as the test material, the effects of spraying EBR with different concentrations (0.10, 0.30, 0.50mg·L^-1) on the chlorophyll content, stomatal aperture, photosynthetic gas exchange parameters and related gene expression of tea leaves were studied. The results show that spraying 0.10 and 0.30mg·L^-1EBR on leaves significantly increased the chlorophyll content of tea leaves on the first day after treatment. Compared with the control condition, chlorophyll content increased by 38.89% and 22.22%, respectively. On the third and fifth days after treatment, the stomatal aperture of tea leaves treated with 0.10 and 0.30mg·L^-1EBR increased significantly. On the first and fifth days after treatment, spraying EBR significantly increased the net photosynthetic rate of tea leaves. At the same time, EBR treatment could significantly up-regulate the expressions of genes involved in BR biosynthesis, chlorophyll biosynthesis, and carbon assimilation. These results indicate that exogenous EBR increased the chlorophyll content and stomata aperture of tea leaves by regulating the expression of related genes, which ultimately promoted the photosynthetic rate of tea plants.

Analysis and Evaluation of Purine Alkaloid Contents in Bitter Tea Germplasm Resources from Guangdong

LI Hongjian, QIN Dandan, JIANG Xiaohui, FANG Kaixing, WANG Qiushuang, PAN Chendong, LI Bo, WANG Qing, WU Hualing

Journal of Tea Science. 2021, 41(1): 71-79. doi:10.13305/j.cnki.jts.2021.01.008

Abstract ( 556 )

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The purine alkaloids of 13 bitter tea germplasms from Guangdong Province along with 28 representative cultivars (lines) from different tea producing areas in China were selected for analysis in this paper. The results indicate that genetic diversity index (H′) of purine alkaloids ranged from 0.78 to 1.94, while the coefficient of variation (CV) ranged from 34.89% to 191.19%. The samples could be divided into 6 groups based on cluster analysis: group Ⅰ, Ⅱ and Ⅲ were predominantly consisted of conventional cultivars with high caffeine content; group Ⅴ contained caffeine-free cultivars from Nankun Mountain, while all samples in group Ⅳ and Ⅵ were bitter tea with high theacrine content. A total of 10 purine alkaloid specific bitter tea resources were identified. Moreover, theacrine showed a gradually decrease trend with the increase of leaf positions but maintained a high level in mature leaves of bitter tea. Taken together, our research provided a basis for genetic improvement of functional tea cultivars with specific purine alkaloids in the future.

Crystallographic Study on the Complex of Catechins and Caffeine

DONG Yanru, CAO Yanyan, LU Jiachun, MEI Sifan, HE Run, CHEN Ping

Journal of Tea Science. 2021, 41(1): 80-89. doi:10.13305/j.cnki.jts.20201127.001

Abstract ( 731 )

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Through HPLC analysis, it was found that catechins and caffeine accounted for more than 88% of the total mass of green tea cream. The CATs-CAF, a simplified green tea cream system, was established by two ester catechins that with the highest content in green tea cream, and their corresponding non-ester catechins complexed with caffeine. The distribution ratio of 4 catechins in precipitate was that EC∶ECG∶EGC∶EGCG≈1∶2∶1∶2. Single crystals were prepared by complexing ECG and EC respectively with caffeine and observed under scanning electron microscopy to record their micro-morphology before and after complexation. Using X-ray single-crystal diffraction to analyze the stereochemical structure, the results show that two needle crystals were formed by intermolecular hydrogen bonding and face-to-face π-π stacking. EC formed O-H...O type hydrogen bonds with adjacent EC and CAF molecules, and π-π stacking occurred between the A ring of EC and the six-membered ring of CAF to form a 1∶1 complex of EC-CAF. While the ECG could form O-H...O and O-H...N type hydrogen bonds with adjacent ECG and CAF molecules, and the π-π stacking of ECG-CAF occurred among all aromatic rings to form a 2∶4 complex, in which the ring A and B of each ECG shared the six-membered ring of CAF separately with the ring B and A of the adjacent ECGs, while the D ring of ECG and the six-membered ring of CAF extended on the a axis in two arrangements.

Effect of Three Antibiotic Treatments on Bacterial Endosymbiont Community of Ectropis Grisescens Warren

WANG Zhibo, BAI Jiahe, ZHOU Xiaogui, GUO Huawei, XIAO Qiang

Journal of Tea Science. 2021, 41(1): 90-100. doi:10.13305/j.cnki.jts.20201130.001

Abstract ( 433 )

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In order to study the effects of three antibiotics on bacterial endosymbiont community of Ectropis grisescens, relative experiment was carried out with three antibiotics (tetracycline, cefalexin and rifampicin) at the concentration of 2.5 mg·mL^-1. Larvae of E. grisescens were fed the tea leaves with antibiotics for continuous 3 generations. Variation of endosymbiont community was studied using 16 S rDNA Illumina MiSeq technique. Besides, the Wolbachia of E. grisescens were detected basing on wsp gene. The results show that abundance and diversity of endosymbiont community in E. grisescens were increased and reduced, respectively under antibiotic treatments. The tetracycline and rifampicin could effectively remove Wolbachia from E. grisescens. Further, the population of E. grisescens without Wolbachia was established, which laid the foundation for the study on function of Wolbachia.

Screening, Identification and Culture Conditions of a High-virulent Isolate of Beauveria against Myllocerinus Aurolineatus

WANG Dingfeng, LI Liangde, LI Huiling, ZHANG Hui, WU Guangyuan

Journal of Tea Science. 2021, 41(1): 101-112. doi:10.13305/j.cnki.jts.2021.01.009

Abstract ( 542 )

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Myllocerinus aurolineatus (Coleoptera: Curculionidae) is one of the most important pests in tea plantation, and chemical control is the usual treatment method for this weevil at present. In order to explore alternative strategy for sustainable control of the weevil, dip method was employed to test the virulence of 12 isolates of Beauveria sp., which isolated from insects of Coleoptera. When inoculated with spore suspension (5.0×10⁷ spores·mL^-1), the strain Bbr1552 showed the highest virulence against the adults of M. aurolineatus, which caused the highest corrected mortality rates of 100%, shortest LT₅₀ of 4.49 d and highest cadaver rates of 69.44%. The LC₅₀ value was 1.55×10⁶ spores·mL^-1 on 7 d (25℃) after inoculation with Bbr1552. According to morphological identification and analysis of rDNA-ITS and Bloc sequences, the strain Bbr1552 was identified to be a B. brongniartii. Besides, the PPDA medium and 25℃ were the most optimal conditions for the colony growth and sporulation of the strain Bbr1552.

Correlation Analysis of Scenting Times and Aroma Components of Fuzhou Jasmine Tea

ZHANG Junjie, FU Tianlong, FU Tianfu, LIN Xingrong, GUO Chen, RAO Genghui, PENG Shanshan, FANG Cai

Journal of Tea Science. 2021, 41(1): 113-121. doi:10.13305/j.cnki.jts.2021.01.010

Abstract ( 695 )

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In this study, Fuzhou jasmine tea with different scenting times was taken to determine relative contents of aroma components by gas chromatography mass spectrometry. Based on jasmine tea flavor (JTF) index, the quality of jasmine tea was evaluated completely. The results show that the relative contents and types of aroma components improved gradually with the increasing of scenting times from one to five and one jacquard, and 77 aroma components were detected finally. The quality of five-scenting jasmine tea was significantly better than four-scenting jasmine tea. Although, the quality of five-scenting jasmine tea was less than that of jasmine tea scented for five times and one jacquard, there was no significant difference. Therefore, five scenting jasmine tea was the best comprehensively. This study provided a reference for aerosol optimizing and processing of jasmine tea.

Optimization of Culture Medium and Quality Analysis of Auricularia Auricula Cultivated by the By-product of Mee Tea

LEI Ting, SUN Feng, MA Xiubing, ZHANG Weihan, GUO Lina, WANG Rui, HAN Renjia, WU Hanping, WANG Yunsheng

Journal of Tea Science. 2021, 41(1): 122-131. doi:10.13305/j.cnki.jts.20201209.004

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Mee tea is the main export green tea in China, named after the eyebrow-like shape. The produce of Mee tea by-product (mainly including tea stalk) during the refining process cannot be avoided. How to make rational use of Mee tea by-product is a key question to improve the added value of Mee tea processing. In this paper, the main cultivated black fungus variety 'Hei 3' in southern Anhui was used as the material, and comprehensive evaluation indicators such as mycelial growth rate, bioavailability, average yield, and nutrient composition were used to study the replacement of sawdust with the by-product of Mee tea as a substrate for the cultivation of black fungus. The results show that the yield of black fungus in the culture medium containing 40% tea stalk was similar to that of the control, which was 59.57 g·stick^-1. While the contents of protein, polysaccharides and flavonoids were higher than those of the control, which increased by 6.29%, 12.95% and 74.17% respectively. The culture substrate with 40% Mee tea by-product was identified as the best culture substrate for the cultivation of black fungus. This study provided a feasible and high value-added way for the comprehensive utilization of Mee tea by-product.

Study on the Measurement of Tea Farmers’ Livelihood Resilience and Influencing Factors: A Case Study of Anxi County

JI Jinxiong, HONG Xiaoyan, ZHU Yongjie

Journal of Tea Science. 2021, 41(1): 132-142. doi:10.13305/j.cnki.jts.2021.01.011

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Based on the theory of livelihood resilience and the analysis framework of sustainable livelihoods, a tea farmer’s livelihood resilience measurement index system was constructed. Anxi County, Fujian Province was selected as the research area, and the comprehensive index method and multiple linear regression model were used to measure tea farmers’ livelihood resilience and identify its influencing factors. The results of the study show that the tea farmers’ livelihood resilience index from high to low is as follows: labor-oriented>agricultural-oriented>pure agricultural type. The overall trend is gradually weakening from non-agricultural income to pure agricultural income. There are significant differences in the three attribute dimensions of buffer capacity, self-organization capacity and learning capacity. Tea garden size, livelihood diversity, degree of non-agriculturalization, credit capacity, organizational participation, technical training quality, and family size have significant and positive effects on the resilience of tea farmers’ livelihoods. While traffic accessibility, age of the head of household, and labor burden have significantly negative effects on tea farmers’ livelihood resilience. Some suggestions were proposed as follows: strengthening the construction of ecological tea gardens, extending the tea industry chain, expanding the coverage of rural inclusive finance, expanding the main body of the new tea industry, and improving the effectiveness of tea farmer training.

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