20 December 2014, Volume 34 Issue 6

    

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  Research Progress of N- methyltransferases Involved in Caffeine Biosynthesis

  YAN Changyu, REN Qiujing, CHEN Xiaofang, LI Bin, CHEN Zhongzheng

  Journal of Tea Science. 2014, 34(6): 531-540. https://doi.org/10.13305/j.cnki.jts.2014.06.013

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  Caffeine is one of the main quality and functional components in beverage such as tea, coffee, etc. At present, a xanthosine→7-methylxanthosine→7-methylxanthine→theobromine→caffeine pathway is supported as the major route to caffeine, and it is synthesized through three methylation reactions by N- methyltransferase and a nucleosidase reaction by nucleoside hydrolase. N- methyltransferases(NMTs) are important enzymes in caffeine synthesis process. In this paper, the profile of caffeine in plant and the pathway of caffeine synthesis were introduced, and the research progress on the enzymology properties, gene cloning and expression, the relationship of gene function and structure of NMTs involved in caffeine biosynthesis were mainly reviewed. Finally, the research emphasis in the field for the future was discussed and prospected.
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  Research of Resistance Mechanism to Ectropis oblique by Tea Plant

  WANG Dan, CHEN Liang

  Journal of Tea Science. 2014, 34(6): 541-547. https://doi.org/10.13305/j.cnki.jts.2014.06.014

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  Ectropis oblique (Prout) seriously damages tea plant and reduces tea quality. It is well documented that different tea cultivars [Camellia sinensis (L.) O. Kuntze] have diverse and complicated responds to the feeding stress caused by E. oblique. So to investigate the mechanisms of resistance to E. oblique by tea plant is of great importance for identifying resistance level of tea cultivars, exploring tolerant genetic resources against insects and creating new insect-resistance materials. The damage situation caused by E. oblique was firstly described, then the new achievements related to resistance mechanism to E. oblique by tea plant were summarized, and some problems in this field were pointed out, and the current research trends and prospects were analyzed.
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  Design and Test for Hydraulic System of Self-propelled Tea Plucker

  HAN Yu, XIAO Hongru, QIN Guangming, CHEN Dongsheng, SONG Zhiyu, DING Wenqin, MEI Song

  Journal of Tea Science. 2014, 34(6): 548-556. https://doi.org/10.13305/j.cnki.jts.2014.06.015

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  To design a simple, reasonable and robust hydraulic system for self-propelled tea plucker, this paper designed the hydraulic system firstly based on analyzing the actions and operating environment of self-propelled tea Plucker, and then conducted a functional-simulation to whole system with Sim Hydraulic, including traveling simulating and plucking simulating. And also the prototype test was carried out. The system consists mainly of three subsystems: two closed travel loops, whose system pressure is 17.6 MPa, encompass separately a variable pump and a constant-displacement motor with a volumetric speed-control scheme; an open loop, whose pressure is 10 MPa, comprises a constant-displacement pump and a constant-displacement motor used for plucking. The disparity between simulating results and the design values of the system pressure was 2.78% and 0.91% respectively, the difference between test values and design values was 4.82% and 14.3%. All in all, both the simulation and the test were basically in accorded with the design, which indicates the well function of the designed hydraulic system meets well the needs of self-propelled tea plucking machine.
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  The Temperature PID Control System of Dryer and Its Application on Dahongpao Baking

  WEI Shiqin, JIN Xinyi, HUANG Jiachun, HAO Zhilong, OUYANG Jingsheng, LIN Jie

  Journal of Tea Science. 2014, 34(6): 557-564. https://doi.org/10.13305/j.cnki.jts.2014.06.016

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  This paper described the structure and principle of the temperature PID control system of dryer, and Dahongpao refined baked application experiment was carried out. The results showed that: When the set temperature is 180℃, the average air temperature is controlled at 181.9℃ by the PID system, and the average air temperature controlled by manual is 188.9℃, the baking temperature controlled by PID control system is more stable than manual control, and coal saving rate is about 22.97%-26.83%. In the two different quality levels of Dahongpao, tea polyphenols in the tea drying controlled by the PID and the manual are reached significant level, the amino acid of first-class Dahongpao reached very significant level, the amino acid and soluble sugar of secondary class Dahongpao reached significant level. The average tea quality scores under temperature PID control is higher than that of manual control.
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  Distribution Characteristics of the Polycyclic Aromatic Hydrocarbon Compounds in Tea Fresh Leaves

  HU Linling, LIU Zunying, LIU Qiuling, FENG Jinyu, LONG Jinhua, XIAO Wenjun

  Journal of Tea Science. 2014, 34(6): 565-571. https://doi.org/10.13305/j.cnki.jts.2014.06.017

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  The distribution characteristics of 16 Polycyclic Aromatic Hydrocarbon(PAHs) in different fresh tea leaves of different tea cultivars in different seasons were analyzed by using HPLC. Results showed that Zhenghedabaicha has lowest concentration of 16 PAHs and lowest standard deviation between Zhenghedabai, Taoyuandaye and Xiangfeicui, the average content is 126.92 μg·kg^-1, the standard deviation is 17.59 μg·kg^-1, the concentration of 16 PAHs and standard deviation in different part of tea leaves is expressed as: the bud< the second leaf< the fourth leaf< the sixth leaf, the PAHs′ concentration in bud is 119.13 μg·kg^-1, standard deviation is 14.36 μg·kg^-1. The concentration of 16 PAHs in different seasons is expressed as autumn<spring<summer in one year. The concentration of PAHs in autumn is 112.75 μg·kg^-1, standard deviation is 11.97 μg·kg^-1, 16 PAHs in fresh tea leaves are mainly composed of 2, 3 rings, account for about 80%. The proportion of 4-6 rings PAHs is lower.
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  A Method for Determination of Total Organic Acids in Tea Plant with Automatic Potentiometic Titration

  ZHU Xujun, YANG Pingping, XU Renkou, WANG Yuhua, LI Xinghui

  Journal of Tea Science. 2014, 34(6): 572-576. https://doi.org/10.13305/j.cnki.jts.2014.06.018

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  A method for determination of total organic acids in tea plant by automatic potentiometic titrator was established in this study. And the content of total organic acids in bud, young leaf, mature leaf and withered leaf were determined by this method. The results showed that after extracting by ethanol, concentrated under reduced pressure, the concentrated solution was alkalized and acidified, then detected with automatic potentiometic titrator, the samples were spiked at the level of 2.0-45.0 mg·g^-1, and the recovery of organic acids range from 96.0%-99.6% with RSD less than 5.7%. This simple and sensitive method meets with the analytical requirement to total organic acids in tea. The content of total organic acids in bud, young leaf, mature leaf and withered leaf was 44.9, 20.1, 21.1 and 1.99 mg·g^-1 respectively.
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  Cloning and Sequence Analysis of CsAP2 Gene from Tea Plant[Camellia sinensis (L.) O. Kuntz]

  FANG Chenggang, XIA Lifei, CHEN Linbo, TIAN Yiping, BAO Yunxiu, SHANG Weiqiong

  Journal of Tea Science. 2014, 34(6): 577-582. https://doi.org/10.13305/j.cnki.jts.2014.06.019

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  The cDNA-AFLP was applied to identify genes expressed differentially between young and mature leaves of tea plant (Camellia sinensis var. assamica, cultivar Zijuan). A cDNA fragment, TDF encoding a APETALA2 was isolated, and containing a complete coding sequence cDNA was cloned by RACE, which encodes a polypeptide of 518 amino acids including two conserved AP2 domains, named CsAP2, sequence alignment showed that CsAP2 protein shared high identity with other plants. APETALA2 gene cloning provided foundation for studying flower development in tea plant.
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  Gene Cloning and Expression Analysis of HMGR in Tea Plant Roots

  LI Yuanhua, LU Jianliang, FAN Fangyuan, SHI Yutao

  Journal of Tea Science. 2014, 34(6): 583-590. https://doi.org/10.13305/j.cnki.jts.2014.06.020

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  By using SSH, the differences in gene expression of root system from Fuding Dabai tea infected by VA mycorrhiza were analyzed and diversity sequences were obtained. The sequence alignment showed that the mentioned sequence contain 3-hydroxy-3-methylglutaryl coenzyme A reductase named HMGR. HGMR full-length sequence was obtained by using RACE. The length of HGMR gene is 2 420 bp, with 1 773 bp ORF (163^rd-1935^th), and the sequence encoded 590 amino acids. Bioinformatics indicated that the HGMR protein’s molecular weight is about 63.5 kD, IEP is 6.8, which located in mitochondria or endoplasmic reticulum membrane. The study also showed expression degree of HGMR is distinct in different cultivars, while it responded obviously to biological and non-biological stress.
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  Effects of Tea Pruning Materials and Tea Polyphenols on Organic Acids Secretion and Mineral Uptake in Tea Plant

  PANG Xin, WANG Yuhua, WANG Weidong, YIN Ying, SHU Zaifa, CHEN Xuan, LI Xinghui

  Journal of Tea Science. 2014, 34(6): 591-600. https://doi.org/10.13305/j.cnki.jts.2014.06.021

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  The effects of aqueous solution of tea pruning materials and tea polyphenols on tea plant [Camellia sinensis (L.)] growth and the mechanisms were investigated using hydroponic culture in this paper. The plants were harvested and root exudates were collected after growing periods of 15, 35, 55, 75 and 95 d. The contents of organic acids in the secretes from roots were determined using a HPLC equipped with C₁₈ column after passed through cation and anion exchange resin and concentrated. Besides, the dry weight, tea polyphenols and mineral uptake were analyzed. The results showed that tea polyphenols added in nutrient solution inhibited the uptake of Ca, Mg, Fe, Mn, Zn and growth rate and induced citric and succinic acids efflux from roots. However, the aqueous solution of tea pruning materials added in nutrient solution promoted the uptake of K, Ca, Mg, Fe, Mn, Zn, Al and growth rate and at the meantime induced oxalic, malic, citric and succinic acids efflux from roots. Besides, the aqueous solution of tea pruning materials also lowered pH of collection solution, which were closely linked with organic acids secretion changes, hinting tea pruning materials may result in soil acidification.
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  Molecular Phylogenetic Analysis of Tea Green Leafhopper (Empoasca vitis) Based on mtDNA COI Sequences

  FU Jianyu, LI Le, YUAN Zhijun, TANG Meijun, XIAO Qiang

  Journal of Tea Science. 2014, 34(6): 601-608. https://doi.org/10.13305/j.cnki.jts.2014.06.022

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  The mtDNA COI genes of 84 samples from 12 populations of tea green leafhopper Empoasca vitis (Göthe) and 62 samples from three leafhopper outgroups of Empoasca flavescens, Erythroneura apicalis and Erythroneura sudra were cloned and sequenced, and their genetic structure and phylogeny were bioinformatically analyzed. Results showed that the genetic distances among 12 tea green leafhopper populations were 0.5%-1.2%, which were all less than the species boundary of 2%, and the obvious genetic differentiation was not elemonstrated. The ML phylogmetic tree also showed that E. vitis was no priority within-population. The genetic distances between E. vitis and other outgroup leafhopper were 14.8%-24.5%, and E. flavescens showed the closest relationship with E. vitis while E. sudra was the most distant species to E. vitis. The phylogenetic tree based on ML method also showed the leafhoppers from tea and grape were one group while peach leafhopper was another divergent group. The genetic distance and phylogenetic relationship of tea leafhopper were revealed by using mtDNA COI biomarker, which provided the foundation for exploring its origin and adaptive mechanism in tea plantation.
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  Classification and Identification of Different Aromatics in Tea Made from Different Cultivar of Fenghuang Dancong

  ZHOU Chunjuan, ZHUANG Donghong, GUO Shoujun, ZHU Hui, MA Ruijun, WU Qinghan

  Journal of Tea Science. 2014, 34(6): 609-616. https://doi.org/10.13305/j.cnki.jts.2014.06.023

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  The volatile compositions of 17 kinds of Fenghuang Dancong Tea with different aromatics were analyzed using a combination of simultaneous distillation extraction and gas chromatography-mass spectrometry (SDE-GC/MS), then compared with their ancestor, narcissus series tea, and the non-narcissus series tea. The results showed that according to the aroma pattern similar to or higher than the rate of 95% , they are classified into seven aroma patterns: Huangzhi aroma(gardenia Magnolia fragrance), Xingren aroma(almond fragrance), Milan aroma (honey-orchid fragrance), Zhilan aroma(iris orchid fragrance), Yulan aroma(magnolia fragrance), Juduozai whose aroma pattern was not identified and Gong aroma. The similarity are different not only between each aromatics and varieties, but also between each aromatics and their original variety. By analyzing the difference in the aroma components of different Fenghuang Dancong tea with same aroma pattern, it showed that Dancong tea with different aroma pattern has content differences on the common components, and each also has its characteristic components. For example, the isoeugenol in the Dancong tea with Zhilan aroma, α-cadinol in the Huangzhi aroma, torreyol, β-ionone and caryophyllene in the Milan aroma and the 4-terpenol in the Juduozai Dancong tea, and methyl anthranilate of the Gong aroma. These components may be the characteristic aroma composition in the respective Fenghuang Dancong tea, and can be used as one of the important basis in the aroma pattern classification in the Fenghuang Dancong tea.
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  Comparison of Parents Identification for Tea Variety Based on SSR, SRAP and ISSR Markers

  LIU Zhen, ZHAO Yang, YANG Peidi, CHENG Yang, NING Jing, YANG Yang

  Journal of Tea Science. 2014, 34(6): 617-624. https://doi.org/10.13305/j.cnki.jts.2014.06.024

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  To identify male parent of Xiangbolv 2 and to provide a reference for the choice of DNA marker in the study of relationship analysis, SSR, SRAP and ISSR were used to identify the male parent of Xiangbolv 2 among 5 possible tea varieties. Percentage of polymorphic bands (PPB), polymorphic information content (PIC), diversity index (DI), resolving power (Rp), marker index (MI) and other indicators were used to compare the marker efficiencies of SSR, SRAP and ISSR. Totally 83 (2.86 per primer) alleles were identified by 29 pairs of SSR primers. The average PPB, PIC, DI, Rp, MI were 77.01%, 0.55, 0.29, 1.31, 0.95 respectively. Meanwhile, 139 (8.18 per primer) alleles were amplified by 17 pairs of SRAP, with the average PPB, PIC, DI, Rp, MI of 71.70%, 0.84, 0.15, 3.65, 3.59 respectively. 90 (9.00 per primer) alleles were detected by 10 ISSR primer, with the average PPB, PIC, DI, Rp, MI of 69.76%, 0.85, 0.15, 4.21, 4.71 respectively. MI, Rp and PIC showed the same trend among SSR, SRAP and ISSR, with the highest value of ISSR, followed by SRAP and SSR, the PPB and DI showed the opposite trend. These results indicated that ISSR and SRAP markers had high marker efficiency, and SSR markers had extensive polymorphism. Similarity coefficients among 7 accessions were different by different 3 DNA markers, but Xiangbolv 2, Xiangbolv and Fuding Dabaicha were gathered together irrespective of DNA markers, indicating that Xiangbolv might be the male parent of Xiangbolv 2.