Intrinsic tensile ductility in strain hardening multiprincipal element metallic glass.

Traditional metallic glasses (MGs), based on one or two principal elements, are notoriously known for their lack of tensile ductility at room temperature. Here, we developed a multiprincipal element MG (MPEMG), which exhibits a gigapascal yield strength, significant strain hardening that almost doubles its yield strength, and 2% uniform tensile ductility at room temperature. These remarkable properties stem from the heterogeneous amorphous structure of our MPEMG, which is composed of atoms with significant size mismatch but similar atomic fractions. In sharp contrast to traditional MGs, shear banding in our glass triggers local elemental segregation and subsequent ordering, which transforms shear softening to hardening, hence resulting in shear-band self-halting and extensive plastic flows. Our findings reveal a promising pathway to design stronger, more ductile glasses that can be applied in a wide range of technological fields.

Tea green leafhopper infestations affect tea plant growth by altering the synthesis of brassinolide.

Tea green leafhoppers are insects widely distributed in major tea-growing areas. At present, less attention has been paid to the study on effect of tea green leafhopper infestation on tea growth phenotype. In this study, tea green leafhoppers were used to treat tea branches in laboratory and co-treated with brassinolide (BL), the highest bioactivity of brassinosteroids (BRs), in tea garden. The results showed that the expression of genes related to BRs synthesis was inhibited and BL content was reduced in tea shoots after infestation by tea green leafhoppers. In addition, area of each leaf position, length and diameter of internodes, and the biomass of the tender shoots of tea plant were decreased after infestation by tea green leafhoppers. The number of trichomes, leaf thickness, palisade tissue thickness and cuticle thickness of tea shoots were increased after tea green leafhoppers infestation. BL spraying could partially recover the phenotypic changes of tea branches caused by tea green leafhoppers infestation. Further studies showed that tea green leafhoppers infestation may regulate the expression of CsDWF4 (a key gene for BL synthesis) through transcription factors CsFP1 and CsTCP1a, which finally affect the BL content. Moreover, BL was applied to inhibit the tea green leafhoppers infestation on tea shoots. In conclusion, our study revealed the effect of plant hormone BL-mediated tea green leafhoppers infestation on the growth phenotype of tea plants.

Differential alterations of CXCR3, CXCR5 and CX3CR1 in patients with immune thrombocytopenia.

As a versatile element for maintaining homeostasis, the chemokine system has been reported to be implicated in the pathogenesis of immune thrombocytopenia (ITP). However, research pertaining to chemokine receptors and related ligands in adult ITP is still limited. The states of several typical chemokine receptors and cognate ligands in the circulation were comparatively assessed through various methodologies. Multiple variable analyses of correlation matrixes were conducted to characterize the correlation signatures of various chemokine receptors or candidate ligands with platelet counts. Our data illustrated a significant decrease in relative CXCR3 expression and elevated plasma levels of CXCL4, 9-11, 13, and CCL3 chemokines in ITP patients with varied platelet counts. Flow cytometry assays revealed eminently diminished CXCR3 levels on T and B lymphocytes and increased CXCR5 on cytotoxic T cell (Tc) subsets in ITP patients with certain platelet counts. Meanwhile, circulating CX3CR1 levels were markedly higher on T cells with a concomitant increase in plasma CX3CL1 level in ITP patients, highlighting the importance of aberrant alterations of the CX3CR1-CX3CL1 axis in ITP pathogenesis. Spearman's correlation analyses revealed a strong positive association of peripheral CXCL4 mRNA level, and negative correlations of plasma CXCL4 concentration and certain chemokine receptors with platelet counts, which might serve as a potential biomarker of platelet destruction in ITP development. Overall, these results indicate that the differential expression patterns and distinct activation states of peripheral chemokine network, and the subsequent expansion of circulating CXCR5+ Tc cells and CX3CR1+ T cells, may be a hallmark during ITP progression, which ultimately contributes to thrombocytopenia in ITP patients.

Dual single atomic Ni sites constructing Janus hollow graphene for boosting electrochemical sensing of glucose.

Single atom catalysts (SACs) have attracted attention due to their excellent catalysis activity under specific reactions and conditions. However, the low density of SACs greatly limits catalytic performance. The three-dimensional graphene hollow nanospheres (GHSs) with very thin shell structure can be used as excellent carrier materials. Not only can its outer surface be used to anchor metal single atoms, but its inner surface can also provide rich sites. Here, a novel step-by-step assembly strategy is reported to anchor nickel single atoms (Ni SAs) on the inner and outer surfaces of GHSs (Ni SAs/GHSs/Ni SAs), which significantly increases the loading capacity of Ni SAs (4.8 wt%). Compared to conventional materials that only anchor Ni SAs to the outer surface of the carrier (Ni SAs/GHSs), Ni SAs/GHSs/Ni SAs exhibits significantly higher electrocatalytic activity toward glucose oxidation in alkaline media. The sensitivity of Ni SAs/GHSs/Ni SAs/GCE is nearly five times higher than that of Ni SAs/GHSs/GCE. Moreover, the sensor based on Ni SAs/GHSs/Ni SAs can detect glucose in a wide concentration range of 0.8 µM-1.1244 mM with a low detection limit of 0.19 µM (S/N = 3). This study not only provides an effective sensing material for glucose detection, but also opens a new avenue to construct high-density metal SACs.

Ultrastrong yet Ductile 2D Titanium Nanomaterial for On-Skin Conformal Triboelectric Sensing.

Conventional titanium (e.g., bulk or thin films) is well-known for its relatively high mechanical strength, excellent corrosion resistance, and superior biocompatibility, which are suitable for biomedical engineering and wearable devices. However, the strength of conventional titanium often trades off its ductility, and their use in wearable devices has not been explored yet. In this work, we fabricated a series of large-sized 2D titanium nanomaterials with the method of polymer surface buckling enabled exfoliation (PSBEE), which possess a unique heterogeneous nanostructure containing nanosized titanium, titanium oxide, and MXene-like phases. As a result, these 2D titaniums exhibit both superb mechanical strength (6-13 GPa) and remarkable ductility (25-35%) at room temperature, outperforming all other titanium-based materials reported so far. More interestingly, we demonstrate that the 2D titanium nanomaterials also showed good performance in triboelectric sensing and can be used to fabricate self-powered, on-skin conformal triboelectric sensors with good mechanical reliability.

Strategies for studying in vivo biochemical formation pathways and multilevel distributions of quality or function-related specialized metabolites in tea (Camellia sinensis).

Tea (Camellia sinensis) contains bioactive metabolites such as catechins, amino acids, caffeine, and aroma compounds that contribute to characteristic tea function and flavor. Therefore, studies on biochemical formation pathways and occurrences of these characteristic specialized metabolites in tea plants are important, providing essential information for the regulation and improvement of tea quality and function. Owing to the lack of a stable genetic transformation system, obtaining direct in vivo evidence of the formation of characteristic tea specialized metabolites is difficult. Herein, we review potential strategies for studying in vivo biochemical formation pathways and multilevel distributions of specialized metabolites in tea. At the individual plant level, stable isotope-labeled precursor tracing is an approach to discovering the pathways of some specialized metabolites specifically occurring in tea and elucidating the formation of tea specialized metabolites in response to stresses. At the within-tissue level, imaging mass spectrometry can be used to investigate the in situ localization of characteristic specialized metabolites within tea tissue without sample destruction. At the cellular or subcellular level, nonaqueous fractionation is a feasible method for characterizing the distributions of nonvolatile metabolites in subcellular organs. These approaches will help explain the characteristic scientific problems in tea secondary metabolism and provide more precise information to improve tea quality or function. HighlightsMultilevel distributions of metabolites in tea are important for tea quality improvement.Stable isotope-labeled precursor tracing method can be used to study formations of tea metabolites at individual plant level.Imaging mass spectrometry can be used to investigate the in situ localization of metabolites within tea tissue.Nonaqueous fractionation is a feasible method for characterizing the distributions of metabolites in subcellular organs.

Nonaqueous fractionation and overexpression of fluorescent-tagged enzymes reveals the subcellular sites of L-theanine biosynthesis in tea.

l-Theanine is a specialized metabolite in the tea (Camellia sinensis) plant which can constitute over 50% of the total amino acids. This makes an important contribution to tea functionality and quality, but the subcellular location and mechanism of biosynthesis of l-theanine are unclear. Here, we identified five distinct genes potentially capable of synthesizing l-theanine in tea. Using a nonaqueous fractionation method, we determined the subcellular distribution of l-theanine in tea shoots and roots and used transient expression in Nicotiana or Arabidopsis to investigate in vivo functions of l-theanine synthetase and also to determine the subcellular localization of fluorescent-tagged proteins by confocal laser scanning microscopy. In tea root tissue, the cytosol was the main site of l-theanine biosynthesis, and cytosol-located CsTSI was the key l-theanine synthase. In tea shoot tissue, l-theanine biosynthesis occurred mainly in the cytosol and chloroplasts and CsGS1.1 and CsGS2 were most likely the key l-theanine synthases. In addition, l-theanine content and distribution were affected by light in leaf tissue. These results enhance our knowledge of biochemistry and molecular biology of the biosynthesis of functional tea compounds.

Low temperature synergistically promotes wounding-induced indole accumulation by INDUCER OF CBF EXPRESSION-mediated alterations of jasmonic acid signaling in Camellia sinensis.

Plants have to cope with various environmental stress factors which significantly impact plant physiology and secondary metabolism. Individual stresses, such as low temperature, are known to activate plant volatile compounds as a defense. However, less is known about the effect of multiple stresses on plant volatile formation. Here, the effect of dual stresses (wounding and low temperature) on volatile compounds in tea (Camellia sinensis) plants and the underlying signalling mechanisms were investigated. Indole, an insect resistance volatile, was maintained at a higher content and for a longer time under dual stresses compared with wounding alone. CsMYC2a, a jasmonate (JA)-responsive transcription factor, was the major regulator of CsTSB2, a gene encoding a tryptophan synthase ß-subunit essential for indole synthesis. During the recovery phase after tea wounding, low temperature helped to maintain a higher JA level. Further study showed that CsICE2 interacted directly with CsJAZ2 to relieve inhibition of CsMYC2a, thereby promoting JA biosynthesis and downstream expression of the responsive gene CsTSB2 ultimately enhancing indole biosynthesis. These findings shed light on the role of low temperature in promoting plant damage responses and advance knowledge of the molecular mechanisms by which multiple stresses coordinately regulate plant responses to the biotic and abiotic environment.

Understanding different regulatory mechanisms of proteinaceous and non-proteinaceous amino acid formation in tea (Camellia sinensis) provides new insights into the safe and effective alteration of tea flavor and function.

Amino acids are the main contributors to tea (Camellia sinensis) flavor and function. Tea leaves contain not only proteinaceous amino acids but also specialized non-proteinaceous amino acids such as L-theanine and γ-aminobutyric acid (GABA). Here, we review different regulatory mechanisms of proteinaceous and non-proteinaceous amino acid formation in tea. The key findings were: (1) High accumulations of proteinaceous amino acids mainly result from protein degradation, which occurs in each tea stage, including preharvest, postharvest, manufacturing, and deep processing; (2) L-Theanine is the most represented non-proteinaceous amino acid that contributes to tea taste and function. Its accumulation is influenced more by the variety than by exogenous factors; and (3) GABA is the second most represented non-proteinaceous amino acid that contributes to tea function. Its formation, and resulting accumulation, are responses to stress. The combination of anoxic stress and mechanical damage are essential for a high GABA accumulation. An understanding of the biosynthesis, metabolism, and regulatory mechanisms of the proteinaceous and non-proteinaceous amino acids during the whole process from raw materials to tea products is necessary to safely and effectively alter tea flavor and function.

Synthesis of porous Co3S4 for enhanced voltammetric nonenzymatic determination of glucose.

Porous Co3S4 was synthesized by a two-step hydrothermal method, and its morphology and structure were characterized by transmission electron microscopy and X-ray diffraction. Electrochemical investigations showed that a glassy carbon electrode modified with Co3S4 exhibits high electrocatalytic activity toward glucose in 0.2 M NaOH solution. Figures of merit for this sensor include (i) a wide linear range (2.0 µM to 1.1 mM), (ii) a working potential near 0.52 V (vs. Ag/AgCl), (iii) high sensitivity (346.7 µA mM-1 cm-2), and (iv) a 0.17 µM detection limit. Graphical abstractPorous Co3S4 was explored as electrocatalyst for glucose oxidation. It exhibits distinctly higher electrocatalytic activity toward glucose oxidation than Co3O4.

Metabolism of Gallic Acid and Its Distributions in Tea (Camellia sinensis) Plants at the Tissue and Subcellular Levels.

In tea (Camellia sinensis) plants, polyphenols are the representative metabolites and play important roles during their growth. Among tea polyphenols, catechins are extensively studied, while very little attention has been paid to other polyphenols such as gallic acid (GA) that occur in tea leaves with relatively high content. In this study, GA was able to be transformed into methyl gallate (MG), suggesting that GA is not only a precursor of catechins, but also can be transformed into other metabolites in tea plants. GA content in tea leaves was higher than MG content-regardless of the cultivar, plucking month or leaf position. These two metabolites occurred with higher amounts in tender leaves. Using nonaqueous fractionation techniques, it was found that GA and MG were abundantly accumulated in peroxisome. In addition, GA and MG were found to have strong antifungal activity against two main tea plant diseases, Colletotrichum camelliae and Pseudopestalotiopsis camelliae-sinensis. The information will advance our understanding on formation and biologic functions of polyphenols in tea plants and also provide a good reference for studying in vivo occurrence of specialized metabolites in economic plants.

Understanding the biosyntheses and stress response mechanisms of aroma compounds in tea (Camellia sinensis) to safely and effectively improve tea aroma.

Metabolite formation is a biochemical and physiological feature of plants developed as an environmental response during the evolutionary process. These metabolites help defend plants against environmental stresses, but are also important quality components in crops. Utilizing the stress response to improve natural quality components in plants has attracted increasing research interest. Tea, which is processed by the tender shoots or leaves of tea plant (Camellia sinensis (L.) O. Kuntze), is the second most popular beverage worldwide after water. Aroma is an important factor affecting tea character and quality. The defense responses of tea leaves against various stresses during preharvest (tea growth process) and postharvest (tea manufacturing) processing can result in aroma formation. Herein, we summarize recent investigations into the biosyntheses of several characteristic aroma compounds prevalent in teas and derived from volatile fatty acid derivatives, terpenes, and phenylpropanoids/benzenoids. Several key aroma synthetic genes from tea leaves have been isolated, cloned, sequenced, and functionally characterized. Biotic stress (such as tea green leafhopper attack) and abiotic stress (such as light, temperature, and wounding) could enhance the expression of aroma synthetic genes, resulting in the abundant accumulation of characteristic aroma compounds in tea leaves. Understanding the specific relationships between characteristic aroma compounds and stresses is key to improving tea quality safely and effectively.

Formation of α-Farnesene in Tea (Camellia sinensis) Leaves Induced by Herbivore-Derived Wounding and Its Effect on Neighboring Tea Plants.

Herbivore-induced plant volatiles (HIPVs) play important ecological roles in defense against stresses. In contrast to model plants, reports on HIPV formation and function in crops are limited. Tea (Camellia sinensis) is an important crop in China. α-Farnesene is a common HIPV produced in tea plants in response to different herbivore attacks. In this study, a C. sinensis α-farnesene synthase (CsAFS) was isolated, cloned, sequenced, and functionally characterized. The CsAFS recombinant protein produced in Escherichia coli was able to transform farnesyl diphosphate (FPP) into α-farnesene and also convert geranyl diphosphate (GPP) to ß-ocimene in vitro. Furthermore, transient expression analysis in Nicotiana benthamiana plants indicated that CsAFS was located in the cytoplasm and could convert FPP to α-farnesene in plants. Wounding, to simulate herbivore damage, activated jasmonic acid (JA) formation, which significantly enhanced the CsAFS expression level and α-farnesene content. This suggested that herbivore-derived wounding induced α-farnesene formation in tea leaves. Furthermore, the emitted α-farnesene might act as a signal to activate antibacterial-related factors in neighboring undamaged tea leaves. This research advances our understanding of the formation and signaling roles of common HIPVs in crops such as tea plants.

Influence of Chloroplast Defects on Formation of Jasmonic Acid and Characteristic Aroma Compounds in Tea (Camellia sinensis) Leaves Exposed to Postharvest Stresses.

Characteristic aroma formation in tea (Camellia sinensis) leaves during the oolong tea manufacturing process might result from the defense responses of tea leaves against these various stresses, which involves upregulation of the upstream signal phytohormones related to leaf chloroplasts, such as jasmonic acid (JA). Whether chloroplast changes affect the formation of JA and characteristic aroma compounds in tea leaves exposed to stresses is unknown. In tea germplasms, albino-induced yellow tea leaves have defects in chloroplast ultrastructure and composition. Herein, we have compared the differential responses of phytohormone and characteristic aroma compound formation in normal green and albino-induced yellow tea leaves exposed to continuous wounding stress, which is the main stress in oolong tea manufacture. In contrast to single wounding stress (from picking, as a control), continuous wounding stress can upregulate the expression of CsMYC2, a key transcription factor of JA signaling, and activate the synthesis of JA and characteristic aroma compounds in both normal tea leaves (normal chloroplasts) and albino tea leaves (chloroplast defects). Chloroplast defects had no significant effect on the expression levels of CsMYC2 and JA synthesis-related genes in response to continuous wounding stress, but reduced the increase in JA content in response to continuous wounding stress. Furthermore, chloroplast defects reduced the increase in volatile fatty acid derivatives, including jasmine lactone and green leaf volatile contents, in response to continuous wounding stress. Overall, the formation of metabolites derived from fatty acids, such as JA, jasmine lactone, and green leaf volatiles in tea leaves, in response to continuous wounding stress, was affected by chloroplast defects. This information will improve understanding of the relationship of the stress responses of JA and aroma compound formation with chloroplast changes in tea.

Molecular detection and genetic characterizations of Cryptosporidium spp. in farmed foxes, minks, and raccoon dogs in northeastern China.

Cryptosporidium spp. are common intestinal protozoa causing diarrhea in humans and a variety of animal species. With the recent development of fur industry, a large number of fur animals are farmed worldwide, especially in China. The existence of identical Cryptosporidium species/genotypes in humans and fur animals suggests zoonotic potential. In order to assess the presence of zoonotic Cryptosporidium species and/or genotypes in farmed fur animals, 367 fecal specimens were collected from 213 foxes, 114 minks and 40 raccoon dogs farmed in Heilongjiang, Jilin, and Liaoning provinces, northeastern China, during the period from June 2014 to October 2016. By PCR and sequencing of the partial small subunit (SSU) rRNA gene of Cryptosporidium, 20 of 367 (5.4%) animal samples were found to be infected, corresponding to 12 of 213 fox samples (5.6%) and 8 of 114 mink samples (7.0%) screened. Three Cryptosporidium species/genotypes were identified: C. canis (n = 17), C. meleagridis (n = 1) and Cryptosporidium mink genotype (n = 2). Two host-adapted C. canis types (C. canis dog genotype and C. canis fox genotype) were found. By PCR and sequencing of the partial 60 kDa glycoprotein (gp60) encoding gene, one mink genotype isolate was successfully subtyped as XcA5G1R1. The three Cryptosporidium species/genotypes identified in this study have been previously reported in humans suggesting that fur animals infected with Cryptosporidium spp. may pose a risk of zoonotic transmission of cryptosporidiosis, especially for the people working in fur animal farming and processing industry.

Differential Accumulation of Anthocyanins in Dendrobium officinale Stems with Red and Green Peels.

Dendrobium officinale stems, including red and green stems, are widely used as a dietary supplement to develop nutraceutical beverages and food products. However, there is no detailed information on pigment composition of red and green stems. Here, we investigated the content and composition of pigments in red and green stems by Ultra-performance liquid chromatography quadrupole time-of-flight mass spectrometry and assessed the differential accumulation of anthocyanins at the molecular level. The color of peels in red stems was caused by the presence of anthocyanins in epidermal cells unlike the peels of green stems. The glucoside derivatives delphinidin and cyanidin are responsible for the red color. Within the D. officinale anthocyanidin biosynthetic pathway, DoANS and DoUFGT, coding for anthocyanidin synthase and UDP-glucose flavonoid-3-O-glucosyltransferase, respectively, are critical regulatory genes related to the differential accumulation of anthocyanidin. These findings provide a more complete profile of pigments, especially anthocyanin, in D. officinale stems, and lay a foundation for producing functional foods.

Formation and Change of Chloroplast-Located Plant Metabolites in Response to Light Conditions.

Photosynthesis is the central energy conversion process for plant metabolism and occurs within mature chloroplasts. Chloroplasts are also the site of various metabolic reactions involving amino acids, lipids, starch, and sulfur, as well as where the production of some hormones takes place. Light is one of the most important environmental factors, acting as an essential energy source for plants, but also as an external signal influencing their growth and development. Plants experience large fluctuations in the intensity and spectral quality of light, and many attempts have been made to improve or modify plant metabolites by treating them with different light qualities (artificial lighting) or intensities. In this review, we discuss how changes in light intensity and wavelength affect the formation of chloroplast-located metabolites in plants.

Functional Characterization of An Allene Oxide Synthase Involved in Biosynthesis of Jasmonic Acid and Its Influence on Metabolite Profiles and Ethylene Formation in Tea (Camellia sinensis) Flowers.

Jasmonic acid (JA) is reportedly involved in the interaction between insects and the vegetative parts of horticultural crops; less attention has, however, been paid to its involvement in the interaction between insects and the floral parts of horticultural crops. Previously, we investigated the allene oxide synthase 2 (AOS2) gene that was found to be the only JA synthesis gene upregulated in tea (Camellia sinensis) flowers exposed to insect (Thrips hawaiiensis (Morgan)) attacks. In our present study, transient expression analysis in Nicotiana benthamiana plants confirmed that CsAOS2 functioned in JA synthesis and was located in the chloroplast membrane. In contrast to tea leaves, the metabolite profiles of tea flowers were not significantly affected by 10 h JA (2.5 mM) treatment as determined using ultra-performance liquid chromatography/quadrupole time-of-flight mass spectrometry, and gas chromatography-mass spectrometry. Moreover, JA treatment did not significantly influence ethylene formation in tea flowers. These results suggest that JA in tea flowers may have different functions from JA in tea leaves and other flowers.

Differential Accumulation of Aroma Compounds in Normal Green and Albino-Induced Yellow Tea (Camellia sinensis) Leaves.

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.

Occurrence of Functional Molecules in the Flowers of Tea (Camellia sinensis) Plants: Evidence for a Second Resource.

Tea (Camellia sinensis) is an important crop, and its leaves are used to make the most widely consumed beverage, aside from water. People have been using leaves from tea plants to make teas for a long time. However, less attention has been paid to the flowers of tea plants, which is a waste of an abundant resource. In the past 15 years, researchers have attempted to discover, identify, and evaluate functional molecules from tea flowers, and have made insightful and useful discoveries. Here, we summarize the recent investigations into these functional molecules in tea flowers, including functional molecules similar to those in tea leaves, as well as the preponderant functional molecules in tea flowers. Tea flowers contain representative metabolites similar to those of tea leaves, such as catechins, flavonols, caffeine, and amino acids. The preponderant functional molecules in tea flowers include saponins, polysaccharides, aromatic compounds, spermidine derivatives, and functional proteins. We also review the safety and biological functions of tea flowers. Tea flower extracts are proposed to be of no toxicological concern based on evidence from the evaluation of mutagenicity, and acute and subchronic toxicity in rats. The presence of many functional metabolites in tea flowers indicates that tea flowers possess diverse biological functions, which are mostly related to catechins, polysaccharides, and saponins. Finally, we discuss the potential for, and challenges facing, future applications of tea flowers as a second resource from tea plants.