Journal of Tea Science

Thinking on the Taxonomy of Camellia sect. Thea

YANG Shixiong

Journal of Tea Science. 2021, 41(4): 439-453. doi:10.13305/j.cnki.jts.2021.04.001

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Camellia sect. Thea, a group of high economic value, is extremely complicated in taxonomy because of the diversity and the continuity of interspecies morphological characters. There exist lots of controversies of current classification systems about sectional taxonomic circumscription and species definition. Here the taxonomic history of Sect. Thea was systematically reviewed. Some taxonomists’ views on the causes of the taxonomic confusion and how to improve the taxonomy were also presented.

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

Identification and Expression Analysis of Glucose-6-hosphate Dehydrogenase Gene (CsG6PDHs) in Camellia sinensis

WANG Yanding, WANG Huan, LI Nana, WANG Lu, HAO Xinyuan, WANG Yuchun, DING Changqing, YANG Yajun, WANG Xinchao, QIAN Wenjun

Journal of Tea Science. 2021, 41(4): 497-510. doi:10.13305/j.cnki.jts.20210622.002

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As a key rate-limiting enzyme in pentose phosphate pathway, glucose-6-phosphate dehydrogenase (G6PDH, EC1.1.1.49) plays an important role in plant growth and development, and also in responding to environmental stresses. However, the function of G6PDH in tea plants has not yet been reported. In our study, 3 G6PDH genes were cloned from tea plant, named as CsG6PDH1 (MW025829), CsG6PDH2 (MW025830) and CsG6PDH4 (MW025831), respectively. Phylogenetic analysis shows that CsG6PDH1 and CsG6PDH4 belong to plastid protein, while CsG6PDH2 belongs to cytoplasmic protein. Quantitative analysis shows that the expressions of CsG6PDHs varied in different tissues. Under cold or Colletotrichum infection treatments, the time course expressions of both CsG6PDH1 and CsG6PDH4 were gradually reduced. Besides, both CsG6PDH1 and CsG6PDH4 were induced by cold acclimation in different tea cultivars. In addition, the expressions of CsG6PDHs were up-regulated during bud dormancy and flush periods. Consequently, our results implicate that CsG6PDHs are widely participated in tea plant growth and development, and also involved in responding to abiotic and biotic stresses. This study provided a theoretical basis for in-depth study of the function of CsG6PDHs in tea plants.

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

Analysis of the Antennal Transcriptome and Olfactory-related Genes in the Agriophara rhombata

LONG Yaqin, LUO Ziwen, WANG Xuesong, LONG Lixue, YU Xiangshuai, LI Jinlong, QU Hao, WANG Yungang, CHEN Linbo

Journal of Tea Science. 2021, 41(4): 553-563. doi:10.13305/j.cnki.jts.20210316.001

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To identify the olfactory-related genes, the transcriptome analysis of the Agriophara rhombata was performed using Illumina HiSeq 4000. Through sequence alignment, 16 027 unigenes were annotated in NR databases. Totally 11 701 unigenes were annotated in GO database, which can be divided into 3 groups according to their functions: cellular component, molecular function and biological process. Totally 6 047 unigenes were further annotated and divided into 25 functional groups in KOG databases. KEGG pathway analysis shows that 12 009 unigenes were annotated into 283 metabolism pathways. According to the annotation information, 238 candidate olfactory-related genes were obtained including 108 odorant binding protein (OBP) genes, 55 odorant /olfactory receptor (OR) genes, 26 gustatory receptor (GR) genes, 25 ionotropic receptor (IR) genes, 11 chemosensory protein (CSP) genes, 4 sensory neuron membrane protein (SNMP) genes, 4 sensory perception (SP) genes , 4 chemosensory receptor (CR) genes and an odorant degrading enzyme (ODE) gene. It was found that 12 odorant binding protein genes, 9 odorant/olfactory receptor genes, 4 pheromone binding protein genes, 3 gustatory receptor genes, chemosensory protein gene and 1ionotropic receptor gene were differentially expressed in the antenna of Agriophara rhombata. In this study, the identification of candidate olfactory-related genes laid a molecular foundation for further studies on gene function and olfactory perception mechanism of the Agriophara rhombata.

Tea Yield Prediction in Zhejiang Province Based on Adaboost BP Model

CHEN Dongmei, HAN Wenyan, ZHOU Xianfeng, WU Kaihua, ZHANG Jingcheng

Journal of Tea Science. 2021, 41(4): 564-576. doi:10.13305/j.cnki.jts.2021.04.009

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The study proposed the tea yield prediction mechanism using the adaboost BP network model with the tea yield level factor and China meteorological forcing dataset in 59 counties of Zhejiang in 1999-2018. We extracted 11 factors including the planting area, the yearly average temperature, the average relative humidity from March to July in the sensitivity analysis. The tea yield prediction model was established then. The result shows that the adaboost BP method with the yield level factor could reach the correlation coefficient as 0.893 and the average of the relative error as 0.187 and the variance of the relative error as 0.316. When selecting history data, the prediction error was lower when the data was closer to the prediction years. Based on the proposed method, the distribution of the prediction error was made. The average relative errors were 18.32%, 16.73% and 22.69% in level 1 high production area, level 2 medium area and level 3 general production area, respectively. The proposed model could realize the tea yield prediction in the counties of Zhejiang Province and could be used in the management of tea production process.

The Sources and Determinants of Productivity Growth for Tea Growers: Evidence from Micro Data of 2011-2017

LYU Jianxing, CHEN Fuqiao, HU Linying, JIANG Aiqin

Journal of Tea Science. 2021, 41(4): 577-591. doi:10.13305/j.cnki.jts.2021.04.010

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Under the background of new economic normal and tea consumption returning to rationality, improving tea productivity has important practical significance for promoting the high-quality development of tea industry. Based on the micro data from 2011 to 2017, the stochastic frontier production function was used to analyze the growth and sources of total factor productivity (TFP) for tea growers, and the micro-pool data from 2013 to 2016 and “one-step” stochastic frontier production function were also used to analyze the technical efficiency and its determinants of tea growers, with particular attention to the impacts of different technology diffusion paths and technology adoption behavior on technical efficiency. The results show: (1) during the study period, the TFP of tea growers increased by an average of 2.71% per year and showed an increasing trend, but it has obvious regional characteristics of high in the West and low in the East. (2) The average annual rate of return to scale and technological progress of tea growers decreased by 0.25% and 1.50%, and their technological efficiency increased by 4.46%. It shows that the main driving force of TFP growth is the improvement of technological efficiency, while the rate of return to scale and technological progress hinder the growth, and both the East and the West show the same characteristics. (3) Through further analysis of the determinants of technical efficiency, the results show that the technical promotion and diffusion paths of tea growers' participation in cooperatives, training in disease and pest control techniques, and the government's early warning information of disease and pest could significantly improve technological efficiency. In addition, the adoption of technologies such as biological control and placement of stained swatches could also significantly improve technical efficiency. Whether they were large growers, exchange the information on disease and pest control experience with other growers, and whether insecticidal lamps were installed had no significant impacts. The conclusions are of great theoretical and practical significance to identify the growth and driving force of tea TFP, and to deeply understand growers' technology adoption behavior and diffusion mechanism.

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