Auswahl der wissenschaftlichen Literatur zum Thema „Young tea cultivars“

Both UV and blue light have been reported to regulate the biosynthesis of flavonoids in tea plants; however, the respective contributions of the corresponding regions of sunlight are unclear. Additionally, different tea cultivars may respond differently to altered light conditions. We investigated the responses of different cultivars (‘Longjing 43’, ‘Zhongming 192’, ‘Wanghai 1’, ‘Jingning 1’ and ‘Zhonghuang 2’) to the shade treatments (black and colored nets) regarding the biosynthesis of flavonoids. For all cultivars, flavonol glycosides showed higher sensitivity to light conditions compared with catechins. The levels of total flavonol glycosides in the young shoots of different tea cultivars decreased with the shade percentages of polyethylene nets increasing from 70% to 95%. Myricetin glycosides and quercetin glycosides were more sensitive to light conditions than kaempferol glycosides. The principal component analysis (PCA) result indicated that shade treatment greatly impacted the profiles of flavonoids in different tea samples based on the cultivar characteristics. UV is the crucial region of sunlight enhancing flavonol glycoside biosynthesis in tea shoots, which is also slight impacted by light quality according to the results of the weighted correlation network analysis (WGCNA). This study clarified the contributions of different wavelength regions of sunlight in a field experiment, providing a potential direction for slightly bitter and astringent tea cultivar breeding and instructive guidance for practical field production of premium teas based on light regimes.

Albino tea plants are mutants that grow albino young leaves owing to lack of chlorophylls under certain environmental conditions. There are two types of albino tea plants grown in production, i.e., light- and temperature-sensitive albino tea cultivars. The former grows albino leaves in yellow color under intensive sunlight conditions and the later grows albino leaves with white mesophyll and greenish vein as the environmental temperature is below 20 °C. Both albino teas attract great attention because of their high levels of amino acids and the “umami” taste. There have been many studies focusing on the temperature-sensitive albino tea plants, whereas little attention has been given to the light-sensitive albino tea cultivars. The characteristics of the albino tea cultivars and the mechanism underlying them were reviewed in the present article based on the published literatures, including chemical compositions, morphological characteristics, and molecular genetic mechanism.

There is increasing interest in the production and consumption of tea (Camellia sinensis L.) processed from purple–leaved cultivar due to their high anthocyanin content and health benefits. However, how and why seasonal changes affect anthocyanin accumulation in young tea leaves still remains obscured. In this study, anthocyanin and abscisic acid (ABA) contents in young leaves of Zifuxing 1 (ZFX1), a cultivar with new shoots turning to purple in Wuyi Mountain, a key tea production region in China, were monitored over four seasons. Young leaves produced in September were highly purplish, which was accompanied with higher anthocyanin and ABA contents. Among the environmental factors, the light intensity in particular was closely correlated with anthocyanin and ABA contents. A shade experiment also indicated that anthocyanin content significantly decreased after 168 h growth under 75% shade, but ABA treatment under the shade conditions sustained anthocyanin content. To confirm the involvement of ABA in the modulation of anthocyanin accumulation, anthocyanin, carotenoids, chlorophyll, ABA, jasmonic acid (JA), and salicylic acid (SA) in the young leaves of four cultivars, including ZFX1, Zijuan (ZJ), wherein leaves are completely purple, Rougui (RG) and Fudingdabaicha (FDDB) wherein leaves are green, were analyzed, and antioxidant activities of the leaf extracts were tested. Results showed that ABA, not other tested hormones, was significantly correlated with anthocyanin accumulation in the purple–leaved cultivars. Cultivars with higher anthocyanin contents exhibited higher antioxidant activities. Subsequently, ZFX1 plants were grown under full sun and treated with ABA and fluridone (Flu), an ABA inhibitor. ABA treatment elevated anthocyanin level but decreased chlorophyll contents. The reverse was true to those treated with Flu. To pursue a better understanding of ABA involvement in anthocyanin accumulation, RNA–Seq was used to analyze transcript differences among ABA– or Flu–treated and untreated ZFX1 plants. Results indicated that the differentially expressed genes in ABA or Flu treatment were mainly ABA signal sensing and metabolism–related genes, anthocyanin accumulation-related genes, light–responsive genes, and key regulatory MYB transcription factors. Taking all the results into account, a model for anthocyanin accumulation in ZFX1 cultivar was proposed: high light intensity caused reactive oxygen stress, which triggered the biosynthesis of ABA; ABA interactions with transcription factors, such as MYB-enhanced anthocyanin biosynthesis limited chlorophyll and carotenoid accumulation; and transport of anthocyanin to vacuoles resulting in the young leaves of ZFX1 with purplish coloration. Further research is warranted to test this model.

The light-sensitive (LS) albino tea plant grows albinic shoots lacking chlorophylls (Chls) under high-light (HL) conditions, and the albinic shoots re-green under low light (LL) conditions. The albinic shoots contain a high level of amino acids and are preferential materials for processing quality green tea. The young plants of the albino tea cultivars are difficult to be cultivated owing to lacking Chls. The mechanisms of the tea leaf bleaching and re-greening are unknown. We detected the activity and composition of photosystem II (PSII) subunits in LS albino tea cultivar “Huangjinya” (HJY), with a normal green-leaf cultivar “Jinxuan” (JX) as control so as to find the relationship of PSII impairment to the albino phenotype in tea. The PSII of HJY is more vulnerable to HL-stress than JX. HL-induced degradation of PSII subunits CP43, CP47, PsbP, PsbR. and light-harvest chlorophyll–protein complexes led to the exposure and degradation of D1 and D2, in which partial fragments of the degraded subunits were crosslinked to form larger aggregates. Two copies of subunits PsbO, psbN, and Lhcb1 were expressed in response to HL stress. The cDNA sequencing of CP43 shows that there is no difference in sequences of PsbC cDNA and putative amino acids of CP43 between HJY and JX. The de novo synthesis and/or repair of PSII subunits is considered to be involved in the impairment of PSII complexes, and the latter played a predominant role in the albino phenotype in the LS albino tea plant.

Light intensity influences energy production by increasing photosynthetic carbon, while phosphorus plays an important role in forming the complex nucleic acid structure for the regulation of protein synthesis. These two factors contribute to gene expression, metabolism, and plant growth regulation. In particular, shading is an effective agronomic practice and is widely used to improve the quality of green tea. Genotypic differences between tea cultivars have been observed as a metabolic response to phosphorus deficiency. However, little is known about how the phosphorus supply mediates the effect of shading on metabolites and how plant cultivar gene expression affects green tea quality. We elucidated the responses of the green tea cultivar Longjing43 under three light intensity levels and two levels of phosphorus supply based on a metabolomic analysis by GC×GC-TOF/MS (Two-dimensional Gas Chromatography coupled to Time-of-Flight Mass Spectrometry) and UPLC-Q-TOF/MS (Ultra-Performance Liquid Chromatography-Quadrupole-Time of Flight Mass Spectrometry), a targeted analysis by HPLC (High Performance Liquid Chromatography), and a gene expression analysis by qRT-PCR. In young shoots, the phosphorus concentration increased in line with the phosphate supply, and elevated light intensities were positively correlated with catechins, especially with epigallocatechin of Longjing43. Moreover, when the phosphorus concentration was sufficient, total amino acids in young shoots were enhanced by moderate shading which did not occur under phosphorus deprivation. By metabolomic analysis, phenylalanine, tyrosine, and tryptophan biosynthesis (PTT) were enriched due to light and phosphorus effects. Under shaded conditions, SPX2 (Pi transport, stress, sensing, and signaling), SWEET3 (bidirectional sugar transporter), AAP (amino acid permeases), and GSTb (glutathione S-transferase b) shared the same analogous correlations with primary and secondary metabolite pathways. Taken together, phosphorus status is a crucial factor when shading is applied to increase green tea quality.

The data on the morphophysiological characteristics of young three-leaf shoots (flashes, the first collection wave) of Camellia sinensis L. cultivars Kolhida and Kimyn, cultivated in the conditions of Russia subtropics (Krasnodar region, Sochi), the accumulation of photosynthetic pigments (chlorophylls a and b), phenolic compounds, including flavanes, and antiradical activity of extracts obtained from them are presented. It has been shown that the Kolhida cultivar is characterized by the formation of larger leaves compared to those of the Kimyn cultivar, as well as a high accumulation of photosynthetic pigments in them. At the same time, in the leaves of both tea representatives, the total content of chlorophylls a and b was higher compared with the stems. A similar tendency is characteristic for the accumulation of the phenolic compounds sum and flavanes, whereas the number of proanthocyanidins (soluble and insoluble) in the stems exceeded that in the leaves by 2–3 times. Both cultures had the same ability to form all forms of phenolic compounds, which is consistent with the data on the activity of L- phenylalanine ammonia-lyase – the key enzyme of their metabolism. It was established that the antiradical activity of extracts obtained from tea leaves was, on average, 30–40% higher than that of the stems and correlated with the content of phenolic compounds in them.

Tea (Camellia sinensis) cultivars with green leaves are the most widely used for making tea. Recently, tea mutants with white or yellow young shoots have attracted increasing interest as raw materials for making “high-quality” tea products. Albino teas are generallycharacterized as having metabolites of relatively high amino acid content and lower catechin content. However, little is known about aroma compounds in albino tea leaves. Herein, we compared original normal leaves (green) and light-sensitive albino leaves (yellow) of cv. Yinghong No. 9. GC-MS was employed to analyze endogenous tea aroma compounds and related precursors. Quantitative real time PCR was used to measure expression levels of genes involved in biosyntheses of tea aromas.The total contents of most endogenous free tea aromas, including aroma fatty acid derivatives, aroma terpenes, and aroma phenylpropanoids/benzenoids, and their glycosidically bound aroma compounds, were lower in yellow leaves than in green leaves. The content of the key precursor geranyl diphosphate (GDP) and expression levels of key synthetic genes involved in the formation of linalool, a major aroma compound in cv. Yinghong No. 9, were investigated. Linalool content was lower in albino-induced yellow leaves, which was due to the lower GDP content compared with normal green leaves.

The qualities of tea (Camellia sinensis) are not clearly understood in terms of integrated leading molecular regulatory network mechanisms behind inorganic phosphate (Pi) limitation. Thus, the present work aims to elucidate transcription factor-dependent responses of quality-related metabolites and the expression of genes to phosphate (P) starvation. The tea plant organs were subjected to metabolomics analysis by GC×GC-TOF/MS and UPLC-Q-TOF/MS along with transcription factors and 13 metabolic genes by qRT-PCR. We found P starvation upregulated SPX2 and the change response of Pi is highly dependent on young shoots. This led to increased change in abundance of carbohydrates (fructose and glucose), amino acids in leaves (threonine and methionine), and root (phenylalanine, alanine, tryptophan, and tyrosine). Flavonoids and their glycosides accumulated in leaves and root exposed to P limitation was consistent with the upregulated expression of anthocyanidin reductase (EC 1.3.1.77), leucoanthocyanidin dioxygenase (EC 1.4.11.19) and glycosyltransferases (UGT78D1, UGT78D2 and UGT57L12). Despite the similar kinetics and high correlation response of Pi and SPX2 in young shoots, predominating theanine and other amino acids (serine, threonine, glutamate, valine, methionine, phenylalanine) and catechin (EGC, EGCG and CG) content displayed opposite changes in response to Pi limitation between Fengqing and Longjing-43 tea cultivars.

Theanine, a unique amino acid in Camellia sinensis, accounts for more than 50% of total free amino acids in tea and has a significant contribution to the quality of green tea. Previous research indicated that theanine is synthesized from glutamic acid (Glu) and ethylamine mainly in roots, and that theanine accumulation depends on the availability of ethylamine which is derived from alanine (Ala) decarboxylation catalyzed by alanine decarboxylase (AlaDC). However, the specific gene encoding AlaDC protein remains to be discovered in tea plants or in other species. To explore the gene of AlaDC in tea plants, the differences in theanine contents and gene expressions between pretreatment and posttreatment of long-time nitrogen starvation were analyzed in young roots of two tea cultivars. A novel gene annotated as serine decarboxylase (SDC) was noted for its expression levels, which showed high consistency with theanine content, and the expression was remarkably high in young roots under sufficient nitrogen condition. To verify its function, full-length complementary DNA (cDNA) of this candidate gene was cloned from young roots of tea seedlings, and the target protein was expressed and purified from Escherichia coli (E. coli). The enzymatic activity of the protein for Ala and Ser was measured in vitro using ultra-performance liquid chromatography coupled with mass spectrometry (UPLC-MS). The results illustrated that the target protein could catalyze the decarboxylation of Ala despite of its high similarity with SDC from other species. Therefore, this novel gene was identified as AlaDC and named CsAlaDC. Furthermore, the gene expression levels of CsAlaDC in different tissues of tea plants were also quantified with quantitative real-time PCR (qRT-PCR). The results suggest that transcription levels of CsAlaDC in root tissues are significantly higher than those in leaf tissues. That may explain why theanine biosynthesis preferentially occurs in the roots of tea plants. The expression of the gene was upregulated when nitrogen was present, suggesting that theanine biosynthesis is regulated by nitrogen supply and closely related to nitrogen metabolism for C. sinensis. The results of this study are significant supplements to the theanine biosynthetic pathway and provide evidence for the differential accumulation of theanine between C. sinensis and other species.

Tea is made from the young leaves of Camellia sinensis, an evergreen, outbreeding tree species. The replacing of seedling with clonal plantations and the use of small numbers of parental plants in breeding programs could cause a decrease in the genetic diversity. The Tea Research Foundation of Central Africa (TRFCA), in Malawi, started tea breeding in 1956. This program has provided new cultivars with increased quality and yield over the first 40 years. However, recently the progress seems to have reached a plateau, suggesting that the maximum potential of the original genetic base has been reached. This study aimed at the evaluation of the genetic diversity within TRFCA cultivars, Malawian seedling accessions and cultivars currently used in China using morphological and microsatellite markers. In the morphological trait analysis, 186 seedling accessions and six TRFCA cultivars were accessed using six morphological traits. The morphological data were scored using two scoring methods, the range scoring method and the mean scoring method. Although the mean scoring method could not discriminate between all the accessions, it is in better agreement with the classification of an expert tea breeder. The six TRFCA cultivars were well distributed among the seedling accessions from Malawi. However, the results of the morphological study were not conclusive since the sample size of the TRFCA cultivars was too small. Microsatellite analysis of 41 TRFCA cultivars, 233 seedling accessions and 22 China origin cultivars revealed only moderate levels of inbreeding. The genetic relationship shows the TRFCA cultivars and the China origin cultivars in their own clusters. The FST values indicated significant differences between the TRFCA and China origin cultivars with all other groups. The allelic richness and the heterozygosity of the TRFCA cultivars are on the low end of the ranges of the groups studied. The TRFCA cultivars may benefit from the introduction of genetically distant tea plants into the breeding program since the level of heterozygosity within this group is relatively low. A second aim of this study is the identification of Random Amplified Polymorphic DNA (RAPD) markers that associate with traits of interest. Primers (17) were selected from previously trait associate plant studies. This selection did not increase the association rate of the primers. The traits that were investigated include Heliopeltis resistance, drought and cold tolerance. One of the tested primers RAPD8, associates with 6 of 8 drought tolerant cultivars. Another RAPD primer previously identified by Mishra and Sen-Mandi (2004) associated with only 4 of 8 drought tolerant cultivars in this study. Neither of the two primers associated with the 8 drought susceptible cultivars. Together these two primers could discriminate all 8 drought tolerant cultivars from the 8 susceptible cultivars and could possibly be used to identify drought tolerant plants. This study contributes to the knowledge of the genetic diversity of tea which may contribute to the management of genetic diversity within tea. In addition a possible trait associated RAPD marker for drought was identified that could be used in the selection for drought tolerant cultivars. AFRIKAANS : Tee word van die jong blare van die Camellia sinensis plant gemaak. Camellia Sinensis is ‘n immergroen boom spesie. Tans word die meeste van die saailing plantasies met klone plantasies vervang wat ‘n negatiewe uitwerking op die genetiese diversiteit van tee het. Tee ontwikkelingsprogramme beïnvloed ook die diversiteit negatief omdat ‘n klein hoeveelheid ouer plante gebruik word. Die Tee Navorsings van Sentrale Afrika (TRFCA) is in Malawi geleë en spesialiseer vanaf 1956 in tee kultivar ontwikkeling. Die kwaliteit en die opbrengs van die vrygestelde kultivars het oor die eerste 40 jaar van die program verbeter. Die vordering in hierdie program is besig om ‘n plato te bereik. ‘n Moontlike verduideliking hiervoor kan wees dat die maksimum kapasitieit van die bestaande genetiese basis bereik is. Die eerste doelwit van hierdie studie is om die genetiese diversitiet van die TRFCA kultivars, geselekteerde saailinge van Malawi en kulticars wat tans in China gekweek word te evalueer deur morfologiese en mikrosateliet merkers te gebruik. In die morfologiese evaluasie is 186 geselekteerde saailinge en ses TRFCA kultivars met behulp van ses morfologiese karaktereineskappe geëvalueer. Die data is geëvalueer deur die gebruik van twee puntestelsels, ’n reeks puntestelsels en ‘n gemiddelde puntestelsel. Alhoewel die gemiddelde puntestelsel nie tussen al die plante kon onderskei nie, het dit ‘n beter groepering ten opsigte van sub-spesies (He was 0.6900) gegee. Die ses TRFCA kultivars is tussen die saailinge van Malawi versprei. Weens die klein hoeveelheid TRFCA kultivars is die gevolgtrekings van die morphologiese evaluasie nie betekenisvol nie. Mikrosateliet evaluasie is gedoen met 41 TRFCA kultivars, 233 geselekteerde saailinge en 22 Chinese kultivars. Gemiddelde vlakke van inteling is opgemerk. In die illustrasie van die genetiese verhouding tussen die plante is die TRFCA kultivars gegroepeer, so ook die Chinese kultivars. Die FST waardes toon betekenisvolle statisitiese verskille tussen TRFCA en die Chinese oorsprong kultivars en al die ander groepe. Die alleliese rykheid van die TRFCA kultivars was aan die onderpunt van die reeks. Hierdie resultate dui daarop dat die TRFCA ontwikkellingsprogram moontlik voordeel kan trek uit die byvoeging van ouer pante wat geneties divers is in die program. Dit mag ‘n positiewe uitwerking hê as gevolg van die ondergemiddelde vlak van die “heterozygosity” in die TRFCA kultivars. ‘n Tweede doelwit van die studie was die identifisering van moontlike “Random Amplified Polymorphic DNA” (RAPD) merkers wat met belangrike kenmerke geassosieer kan word. RAPD merkers (17) wat geïdentifiseer is in vorige kenmerkassosiasiestudies in ander gewassse is geselekteer. Die seleksie van hierdie merkers het nie die assosiasie persentasie verhoog nie. Die kenmerkke wat ondersoek is, was Heliopeltis weerstand, droogte toleransie en koue toleransie. Een van die merkers, RAPD8 assosieer met 6 van die 8 droogte toleransie kultivars. Die RAPD merker wat deur Mishra and Sen-Mandi (2004) geïdentifiseer is, assosieer met 4 van die 8 droogte toleransie kultivars. Beide die merkers assosieer met geen van die droogte sensitiewe kultivars nie. Gesamentlik kon die twee RAPD merkers al 8 van die droogte toleransie kultivars van die sensitiewe kultivars onderskei. Hierdie studie dra by tot die kennis van die genetiese diversitiet van tee wat kan lei to die beter bestuur wan die tee ontwikkelingsprogram. Veder is ‘n moontlike merker vir droogte toleransie geïdentifiseer wat gebruik kan word in die seleksie van moontlike droogte bestande kultivars.
Dissertation (MSc)--University of Pretoria, 2009.
Biochemistry
unrestricted

With the development of society, the rise of education level and the improvement of quality of life, young parents are increasingly willing to provide more abundant and comprehensive preschool education for their children, and preschool education products have gradually become a new trend. Our team will design a children's programming robot for preschool children, to establish programming thinking for children, increase pleasure of learning, and enhance parent-child interaction space. This design adopts the methods of questionnaire survey, user interview and literature retrieval to deeply understand the pain points of children's preschool education, the development status of domestic early childhood education products, and children's preferences, so as to determine the product use process, product function structure and product packaging. The design uses on-chip sensors and priority commands combined with ergonomics and perceptual engineering. Children can play arithmetic games through the combination of the main robot and the control panel, and parents can help children learn and play through mobile application. The product have the ability to cultivate and rich preschool children's scientific way of thinking and problem-solving ability，so that children can use scientific thinking to explain the phenomena and problems in the future, and they can get all-round learning and development at last. After the usability test, the interviewees and their parents believed that the design had certain educational effect.

"Philosophical games provide an innovative transformative structure in the learning process for all levels of formal education. The motivation is to provide elementary school teachers with an innovative methodology for Game-based-Learning of Philosophy/in Philosophy teaching. A combination and attentive collaboration of Philosophy, Art and games/ Game-based Learning provides new tools in approaching and solving the problems that education faces today. Since Game-based Learning constitutes a strong trend in technologically enhanced learning, is the, where/with the employment of gaming elements both in learning content and learning pathways, the proposed methodology leads to a series of novel applications about teaching philosophy that enable young agents to cultivate hypothetic-deductive and critical thinking with a positive attitude towards others and developing feelings of constructive antagonism. The teaching scenario proposed aims at cultivating hypothetic – deductive and critical thought/moreover, enhances the linguistic ability in the vocabulary of ancient Greek philosophy as well. The scenario is part of a game suite entitled “Entering the Socratic school” and targets 10–12-year-old children. It is easy to implement on any digital platform with open-source tools used by almost every teacher. The game elements rely on the structure of the learning content rather than on the digital tools themselves. The methodology consists in designing a concept map and defining the game narrative, the game levels and transitions between levels, the mechanics to be used, such as polls, badges, and leaderboards. Online activities include digital games such as quizzes and crossword puzzles, student generated comic stories, and a digital guide. They are complemented by physical activities involving movement and dialogue using fishbowl techniques and Socratic circles. The proposed teaching scenario will be implemented in the classroom in the following academic year and our work team applies interdisciplinary approaches inspired by at least three different fields of expertise."

What would cities look like if they were designed for the most vulnerable? This question proved fertile ground for a research-based pedagogy focused on one specifically vulnerable group—young children—disproportionately impacted by current social unrest, ecological degradation, and extreme urbanization; and yet seldomly the subject of architectural research or education except in limited typologies, e.g. schools and playgrounds—where they are segregated into. The two-semester research studio asked, what if instead of more or better spaces dedicated to children, the entire city was redesigned for them? Students examined the child’s experience in the contemporary city and the way design turns children’s vulnerability into a liability, especially in the context of urbanization and climate change. During the first of two semesters, students collaborated in transdisciplinary research resulting in a jointly-authored framework of evidence-based design principles: playfulness, safety, health, sustainability, and inclusivity; arguing how designing for children would make a better city for everyone. Drawing on ample evidence of how open and frequent access to immersive experiences in natural landscapes positively influence children’s cognitive, physical and emotional development; the course challenged whether these “natural experiences” are at odds with dense and compact urban development. This polemic generated a challenge for design research during the second semester: how to design “natural experiences” into everyday spaces of dense cities, beyond the centralized park? This was a point of departure for ten individual design investigations, that together illustrate the potential for a new constructed urban landscape. Projects focused in the city of Boston, including planning for inclusive housing, transportation, and coastal resilience; and hybrids of socio-ecological infrastructure and learning environments. This pedagogical analysis reveals how transdisciplinary research expands the definition of vulnerability, cultivates genuine empathy, and builds confidence in designers’ social agency; but also uncovers unique challenges and opportunities for architectural education and practice.