Journal of Tea Science

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

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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.

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

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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.

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

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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.

Phylogenetic Analysis of NUDX1 Gene Involved in Geraniol Biosynthesis

ZHOU Hanchen, YANG Jihong, XU Yujie, WU Qiong, LEI Pandeng

Journal of Tea Science. 2022, 42(5): 638-648. doi:10.13305/j.cnki.jts.2022.05.001

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Geraniol is an acyclic monoterpene alcohol, which plays key roles in plant-environment interactions, such as pest repelling, antimicrobial activity, and pollinator attraction as well as the aroma traits for tea plants. It was reported that a cytosolic Nudix hydrolase (NUDX1) catalyzes geranyl pyrophosphate (GPP) into geranyl monophosphate (GP), followed by dephosphorylation with an endogenous phosphatase to produce geraniol. Two homologues of AtNUDX1 were found in tea genome (CsNUDX1-cyto and CsNUDX1-chlo) with different subcellular location. Searching the homologues of AtNUDX1 on Phytozome shows that fifty-eight plant species contain the homologues of AtNUDX1 (with identities>64%). However, no homologue of AtNUDX1 was found in the genomes of grass species, with the exception of Brachypodium distachyon. We thus detected AR2000-enzymed geraniol in fresh leaves of rice, wheat, maize, and tea plants. The results show that free geraniol was undetectable in fresh leaves of rice, wheat and maize, where as young shoots of four tea cultivars had high levels of geraniol (0.87-4.12 μg·g^-1). Two CsNUDX1 genes were highly expressed in young tea leaves and had a positive correlation (above 0.7) with the accumulation of geraniol. This study shows that NUDX1s are widely present in plant genome, which are closely related to the formation of geraniol.

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

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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.

Ameliorative Effect of Several Measures on Soil Physicochemical Properties and Microbial Community Structures in Acidified Tea Gardens

LI Yanchun, WANG Hang, LI Zhaowei, YE Jing, WANG Yixiang

Journal of Tea Science. 2022, 42(5): 661-671. doi:10.13305/j.cnki.jts.2022.05.009

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Acidification of tea garden soil is an important factor that restricts sustainable production of tea plants. Field plot experiments were conducted to study the effects of several improvement measures on acidified tea soils, which would provide scientific basis to improve the soil quality. The experiment involved several treatments: (1) pure chemical fertilizer (routine fertilization, NPK), (2) chemical fertilizer plus 10 t•hm^-2 biochar (NPK+BC10), (3) organic manure substituted 50% of chemical fertilizer (OM50), (4) organic manure substituted 50% of chemical fertilizer plus lime (OM50+Lime), (5) organic manure substituted 50% of chemical fertilizer plus 10 t•hm^-2 biochar (OM50+BC10), (6) organic manure substituted 50% of chemical fertilizer plus 20 t•hm^-2 biochar (OM50+BC20), and (7) organic manure substituted 50% of chemical fertilizer plus 40 t•hm^-2 biochar (OM50+BC40). After two years of continuous application, soil samples were taken to determine the soil acidity, the nutrient contents, and the microbial community. The microbial community structure was measured using phospholipid fatty acid (PLFA) and Biolog technology. Compared with NPK, soil pH were significantly increased by 1.10, 0.49 and 0.68 units, and base saturation were significantly increased by 114.01%, 55.92% and 58.62% in OM50+Lime, OM50+BC20, and OM50+BC40 treatments, respectively. Compared with NPK, soil organic carbon contents under OM50+BC10, OM50+BC20 and OM50+BC40 treatments were significantly increased by 29.68%, 41.04% and 59.37%, respectively. All treatments had no significant effect on soil nitrate nitrogen content, while the ammonium nitrogen contents under OM50, OM50+BC20 and OM50+BC40 treatments were significantly increased by 40.27%, 44.77% and 41.77% compared with NPK. NPK+BC10, OM50+BC10, OM50+BC20 and OM50+BC40 significantly increased soil microbial activity, species richness, diversity and homogeneity of microbial community. OM50+BC10, OM50+BC20 and OM50+BC40 treatments significantly reduced the ratios of fungi to bacteria, indicating that they increased the stability of soil ecosystem in the short term. The ratio of gram-negative bacteria to gram-positive bacteria under OM50+Lime treatment was significantly lower than that under NPK, which indicates that soil microorganism under OM50+Lime suffered the greater environmental stress than that under other treatments. In summary, OM50+Lime, OM50+BC20 and OM50+BC40 had obvious improvement effect on acidified tea garden soil, while OM50+BC20 and OM50+BC40 had better improvement effect on soil microbial community properties than OM50+Lime. Simultaneous considering ameliorative effect and cost of economy, OM50+BC20 was the best improvement scheme.

Effects of Organic Management Mode on Soil Fungal Community Structure and Functions in Tea Gardens

WANG Feng, CHEN Yuzhen, WU Zhidan, YOU Zhiming, YU Wenquan, YU Xiaomin, YANG Zhenbiao

Journal of Tea Science. 2022, 42(5): 672-688. doi:10.13305/j.cnki.jts.2022.05.008

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To study the soil fungal community compositions and functional groups under different management practices and slope positions, soil samples derived from the topsoil (0-20 cm) were collected from the upper, middle, and lower slope positions of conventional and organic tea gardens. High-throughput sequencing, functional predictions and the molecular ecological network analysis were performed to investigate the community structures, functional groups and ecological network of soil fungi, respectively. The two-way ANOVA including management practices and slope positions showed that the two-way interaction had no effect on the soil fungal community α-diversity. Regardless of the management practices and the slope positions, the predominant fungal phyla were Ascomycota, Basidiomycota and Mortierellomycota. Management practices did not change the compositions of dominant fungal species, but affected their relative abundance. Principal coordinate analysis (PCoA) shows that the soil fungal community structures differed significantly among different management practices. The community structures of soil fungi at different slope positions were noticeably different under the conventional planting pattern (P<0.05), but were similar under the organic planting pattern (P>0.05). The linear discriminant analysis effect size (LEfSe) analysis shows that 37 biomarkers were very sensitive to the changes in the management, with different management practices enriching for different fungal populations. The numbers of degree, clustering, edges, degree centrality and closeness centrality of the fungal interaction network under the organic planting pattern were all higher than those under the conventional planting pattern, indicating that the fungal networks were more complex in the organic tea garden. Saprotrophic fungi were the dominant fungal group across all tea gardens (66.67%~70.18%). The effects of the management practices on soil fungal functions were obvious. Compared to those under the conventional planting pattern, the average abundance of endophyte-litter saprotroph-soil saprotroph, wood saprotroph and animal pathogen-endophyte-plant pathogen-undefined saprotroph significantly increased, but the average abundance of undefined saprotroph, plant pathogen and animal pathogen-plant pathogen-undefined saprotroph remarkably decreased. The spearman correlation analysis and the redundancy analysis (RDA) show that soil total phosphorus, available phosphorus, total potassium, organic matter, cation exchange capacity and pH were the main factors affecting the abundance and diversity of the soil fungal community. Organic planting drastically changes the structure and the compositions of the soil fungal community, enhances fungal network complexity and stability, and thus is beneficial to maintain the sustainable ecosystem in tea garden soil.

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

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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.

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

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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.

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

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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.

Preparation of Nanoparticules with Chitosan Complexed β-lactoglobulin Loaded EGCG and their Effects on Blood Glucose in Diabetic Mice

CHEN Ke, WANG Yuanzhu, YANG Xiaoying, ZHANG Dongying, ZHU Qiangqiang

Journal of Tea Science. 2022, 42(5): 731-739. doi:10.13305/j.cnki.jts.2022.05.003

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As the main bioactive component in tea, EGCG has abundant physiological functions. However, its low stability makes it easy to be degraded and has low bioavailability. In this experiment, carboxymethyl chitosan (CMC), chitosan hydrochloride (CHC), and β-lactoglobulin (β-LG) were used as wall materials to encapsulate EGCG. The microscopic morphology of particles were observed through electron microscope microscopic morphological observation, structural characterization (measurement of particle size, Zeta potential). The entrapment efficiency and simulated gastrointestinal fluid release rate were determined by HPLC. Finally, the activities of nanoparticles were explored by measuring the effect of nanoparticles on blood glucose in diabetic mice. The result shows that the prepared CS-β-LG-EGCG nanoparticles had complete structures, particle size of 10-100 nm, and certain dispersibilities. The entrapment efficiency was greater than 50%, and it had a slow-release effect in intestinal and gastric juices. CS-β-LG-EGCG nanoparticles had no antagonistic effect with insulin. Compared with uncoated EGCG, the sustained-release effect of the particles can slow down the recovery of blood glucose.

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

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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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