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Abstract: Cinnamyl alcohol dehydrogenase (CAD; EC 1.1.1.195) is considered to be a key enzyme in lignin biosynthesis, but little was known about CADs in tea plants (Camellia sinensis). A full-length cDNA sequence (CsCAD2) was isolated by suppressive subtractive hybridization (SSH) in Ectropis oblique feeding-induced tea plants, and another two full-length cDNA sequences (CsCAD1 and CsCAD3) were obtained from a transcriptome obtained by deep sequencing. However, they showed only 20–54% identities. Phylogenetic analysis revealed that they belonged to three different families. DNA gel blotting analysis revealed that two copies of CsCAD1 and CsCAD2 genes existed in tea genome, but CsCAD3 likely had only one copy. Recombinant proteins of these CsCADs were produced in Escherichia coli. The activity of purified recombinant CsCAD2 protein was up to 0.43μmolmin−1 mg−1. However, the other two recombinant proteins had lower activities, probably due to incomplete refolding. qRT-PCR analysis indicated that while CsCAD3 was strongly up-regulated in tea plants after E. oblique attack and mechanical damage, CsCAD1 and CsCAD2 showed only moderate or no changes in transcript levels. Treatment of defence-related hormones methyl jasmonate (MeJA) and salicylic acid (SA) elevated the expression of CsCAD1 and CsCAD2, but decreased the transcript abundance of CsCAD3. The transcript levels of CsCAD2 did not change after applying abscisic acid (ABA), whereas CsCAD1 and CsCAD3 were induced. These results suggested that these three CsCAD genes in tea plants may play a role in defense against insects and pathogens and adaptation to abiotic stresses and these genes likely have divergant functions. [Copyright &y& Elsevier]

Abstract: Theanine synthetase (TS) is an enzyme involved in theanine biosynthesis in tea plants. Recent studies have revealed that theanine biosynthesis, derived from nitrogen metabolism in tea (Camellia sinensis L.) plants, could be influenced by salt treatment. We have characterized CsTS at the molecular and biochemical level. The expression pattern of CsTS protein was examined by western blot using a self-prepared polyclonal antibody with high specificity and sensitivity. The effect of salt treatment on the levels of theanine synthesis was investigated in this study. Levels of theanine and the total free amino acids were gradually increased in shoots, and reached the maximum on the 8th day after treatment (DAT). The immunoblotting analysis suggested the accumulation of CsTS protein had increased gently up to 8 DAT, and subsequently declined, both in roots and shoots, which is one of the main evidences that resulted in the variation of theanine concentration under salt treatment. Together, these data revealed that theanine synthesis takes place both in root and shoot and CsTS accumulation is positively affected by salt treatment. [Copyright &y& Elsevier]

Abstract: Trigonelline is a major component in coffee seeds and may contribute to the bitter taste of the resultant beverage. To determine the trigonelline biosynthetic pathway in coffee fruits, we investigated the metabolic fate of [carboxyl-14C]nicotinic acid riboside and in situ activity of related enzymes. Exogenously supplied [carboxyl-14C]nicotinic acid riboside was rapidly converted to nicotinic acid mononucleotide and was utilized for NAD synthesis. Nicotinic acid riboside was also used for trigonelline synthesis, but this process took longer than NAD synthesis. These results indicate that an efficient nicotinic acid riboside salvage system functions in coffee fruits, and that trigonelline is synthesized mainly from nicotinic acid produced by the degradation of NAD. [Copyright &y& Elsevier]

Abstract: The distribution of phenolic compounds in young and developing leaves, stems, main and lateral roots and cotyledons of 8-week-old tea (Camellia sinensis) seedlings was investigated using HPLC-MS2. Fourteen compounds, flavan-3-ols, chlorogenic acids, and kaempferol-O-glycosides, were identified on the basis of their retention time, absorbance spectrum, and MS fragmentation pattern. The major phenolics were (−)-epigallocatechin-3-O-gallate and (−)-epicatechin-3-O-gallate, located principally in the green parts of the seedlings. Considerable amounts of radioactivity from [ring-14C]phenylalanine were incorporated in (−)-epicatechin, (−)-epigallocatechin, (−)-epicatechin-3-O-gallate and (−)-epigallocatechin-3-O-gallate, by tissues of young and developing leaves and stems. Expression of genes encoding enzymes involved in flavan-3-ol biosynthesis, CHS, CHI, F3H, F3′5′H, DFR, ANS, ANR and LAR was investigated. Transcripts of all genes, except LAR, were more abundant in leaves and stems than in roots and cotyledons. No significant difference was found in the amount of transcript of LAR. These findings indicate that in tea seedlings flavan-3-ols are produced by a naringenin-chalcone→naringenin→dihydrokaempferol pathway. Dihydrokaempferol is a branch point in the synthesis of (−)-epigallocatechin-3-O-gallate and other flavan-3-ols which can be formed by routes beginning with either a flavonoid 3′-hydroxylase mediated conversion of the flavonol to dihydroquercetin or a flavonoid 3′,5′-hydroxylase-catalysed conversion to dihydromyricetin with subsequent steps involving sequential reactions catalysed by dihydroflavanol 4-reductase, anthocyanidin synthase, anthocyanidin reductase and flavan-3-ol gallate synthase. [Copyright &y& Elsevier]

Abstract: To determine whether caffeine biosynthesis is controlled by the availability of purine precursors and/or methyl-donors, we examined the effect of some purine compounds on purine alkaloid accumulation, using tea callus cultures. No stimulation of caffeine biosynthesis was observed when the calli were cultured with 0.5mM adenosine, guanosine or hypoxanthine for 3 weeks. However, 0.5mM paraxanthine doubled the caffeine level relative to controls. Adenosine stimulated the growth of callus and reduced the caffeine concentration 3 months after inoculation. These results indicate that methylation of xanthosine by 7-methylxanthosine synthase is the most plausible rate-limiting step of caffeine biosynthesis; the supply of non-methylated purine precursors or availability of S-adenosyl-l-methionine are not the principal controlling factors of caffeine biosynthesis. Adenosine salvage to adenine nucleotide synthesis may contribute to the growth of tea calli, but not to caffeine biosynthesis. [Copyright &y& Elsevier]

Abstract: Theanine (γ-glutamylethylamide) is the most abundant free amino acid in tea seedlings, and is distributed in cotyledons, shoots and roots. Theanine was synthesised from 15N-labelled (NH4)2SO4, glutamic acid and alanine and from 14C-labelled ethylamine in all parts of seedlings. When (15NH4)2SO4 was supplied to intact seedlings in liquid culture, incorporation of 15N into theanine in roots was greater than in shoots. Incorporation into theanine was negligible in cotyledons, but theanine synthesis in roots and shoots was reduced in seedlings with cotyledons detached. Expression of theanine synthetase genes (TS1 and TS2) was found in all organs, but the transcript level was significantly lower in cotyledons. These results suggest that theanine can be synthesised from glutamic acid and ethylamine derived from alanine in all parts of tea seedlings. However, supplied NH3 exogenously to intact seedlings was converted to theanine mainly in roots. Amino acids stored in cotyledons may also be utilised for theanine synthesis in all parts of seedlings. [Copyright &y& Elsevier]

Abstract: ATP sulfurylase, the first enzyme in the sulfate assimilation pathway of plants, catalyzes the formation of adenosine phosphosulfate from ATP and sulfate. Here we report the cloning of two cDNAs encoding ATP sulfurylase (APS1 and APS2) from Camellia sinensis. They were isolated by RT-PCR and RACE-PCR reactions. The expression of APS1 and APS2 are correlated with the presence of ATP sulfurylase enzyme activity in cell extracts. APS1 is a 1415-bp cDNA with an open reading frame predicted to encode a 360-amino acid, 40.5kD protein; APS2 is a 1706-bp cDNA with an open reading frame to encode a 465-amino acid, 51.8kD protein. The predicted amino acid sequences of APS1 and APS2 have high similarity to ATP sulfurylases of Medicago truncatula and Solanum tuberosum, with 86% and 84% identity respectively. However, they share only 59.6% identity with each other. The enzyme extracts prepared from recombinant Escherichia coli containing Camellia sinensis APS genes had significant enzyme activity. [Copyright &y& Elsevier]

Abstract: The theanine content of the leaves of 27 species or varieties of Theaceae plants was investigated. Theanine was present in 21 species or varieties, but in much lower amounts (<0.2 μmol/g fresh weight) than the quantity detected in Camellia sinensis var. sinensis. The major free amino acids in leaves of four species belonging to the genera Schima and Eurya, were glutamic acid, aspartic acid, glutamine, asparagine, alanine and proline and content of these amino acids is similar to or higher than theanine. Accumulation of free amino acids in these plants was generally lower than in C. sinensis var. sinensis. The biosynthetic activity of theanine, assessed by the incorporation of radioactivity from [14C]ethylamine, was detected in seedlings of two species of Schima. The theanine biosynthetic activity in roots was higher than that of leaves. [Copyright &y& Elsevier]

Abstract: The metabolic fate of [carbonyl-14C]nicotinamide was surveyed in leaf disks of seven mangrove species, Bruguiera gymnorrhiza, Rhizophora stylosa, Kandelia obovata, Sonneratia alba, Pemphis acidula, Lumnitzera racemosa and Avicennia marina, with and without 250mM NaCl. Uptake of [14C]nicotinamide by leaf disks was stimulated by 250mM NaCl in K. candel, R. stylosa, A. marina and L. racemosa. [Carbonyl-14C]nicotinamide was converted to nicotinic acid and was utilised for the synthesis of nucleotides and nicotinic acid conjugates. Formation of nicotinic acid by the deaminase reaction was rapid; there was little accumulation of nicotinamide in the disks 3h after administration. Radioactivity from [carbonyl-14C]nicotinamide was incorporated into pyridine nucleotides (mainly NAD and NADP) in all mangrove leaves, and the rates varied from 2% (in L. racemosa) to 15% (S. alba) of the total radioactivity taken up. NaCl generally reduced nicotinic acid salvage for NAD and NADP. In all mangrove leaf disks, the most heavily labelled compounds (up to 70% of total radioactivity) were trigonelline (N-methylnicotinic acid) and/or nicotinic acid N-glucoside. Trigonelline was formed in all mangrove plants, but N-glucoside synthesis was found only in leaves of A. marina and K. obovata. In A. marina, incorporation of radioactivity into N-glucoside (51%) was much greater than incorporation into trigonelline (2%). In general, NaCl stimulates the synthesis of these pyridine conjugates. The rate of decarboxylation of nicotinic acid in roots of A. marina seedlings was much greater than for the corresponding reaction observed in leaves. [Copyright &y& Elsevier]

[Display omitted] • Over-fired drying can significantly improve the quality of LAGP tea. • LC–MS, HPLC and GC–MS revealed the taste and aroma compounds due to TSD and PLD. • A total of 5 compounds related to taste were selected by DOT > 1. • Concentrations of volatiles were 45.46% higher after PLD treatment. Lu'an Guapian (LAGP) tea, a representative Chinese roasted green tea, undergoes significant changes in taste and aroma during over-fired drying. However, limited studies have been conducted on these effects. This study employed metabolomics and sensory histology techniques to analyze non-volatile and volatile compounds the second drying and pulley liquefied gas drying (PLD) samples. The results revealed that after PLD, the samples exhibited lower umami, bitterness, and astringency; whereas floral, sweet, roasted, cooked corn-like, and cooked chestnut-like aromas became stronger. Among them, the content of (−)-epigallocatechin gallate, glutamic acid, and theogallin, which were closely related to taste, decreased by 4.5 %, 12.3 %, and 10.4 %, respectively. Eight key aroma components were identified as the main contributors to the sample aroma changes: (E)- β -ionone, dimethyl sulfide, (E,E)-2,4-heptadienal, geraniol, linalool, benzeneacetaldehyde, 2-ethyl-3,5-dimethylpyrazine, and hexanal. This study provides a theoretical basis for enhancing the quality of LAGP teas. [ABSTRACT FROM AUTHOR]

Global warming has multifarious effects on crop growth and productivity. Nonetheless, the effects of moderate-high temperatures and melatonin on tea yield and quality remain unclear. In this study, we found that melatonin, a universal growth stimulatory molecule, not only promotes photosynthesis and biomass accumulation in tea plants (Camellia sinensis L.) but also improves tea quality under sub high temperature (SHT). SHT increased the dry biomass and photosynthesis by 40.8% and 28.1%, respectively, and exogenous melatonin caused a further improvement. Moreover, SHT increased the total polyphenol concentrations and decreased the free amino acid concentrations, leading to a significant increase (68.2%) in polyphenol to free amino acid ratio. However, melatonin decreased the polyphenol to free amino acid ratio by delicately improving the concentrations of polyphenols and amino acids. Consistent with the total polyphenol, melatonin increased the concentrations of (-)-catechin, (-)-gallocatechin (GC), and (-)-epigallocatechin-3-gallate (EGCG) in tea leaves. The qRT-PCR analysis revealed that melatonin increased the transcript levels of catechins biosynthesis genes, such as CsCHS, CsCH1, CsF3H, CsDFR, CsANS, CsLAR , and CsANR under SHT. Meanwhile, the theanine concentration was decreased by SHT, which was attributed to the attenuated expression of CsGS, CsGOGAT, CsGDH , and CsTS1. Nonetheless, melatonin significantly increased those transcripts and the content of theanine under SHT. Melatonin also increased the caffeine content by inducing the expression of CsTIDH, CssAMS , and CsTCS1. These results suggest that melatonin could positively alter tea growth and quality by modulating the photosynthesis and biosynthesis of polyphenols, amino acids, and caffeine in tea leaves under SHT. [ABSTRACT FROM AUTHOR]

• Increase of roasting raised odor attributes of fried, crispy rice, smoky-burnt. • The change in odor attributes is related to the content of heterocyclic compounds. • Metabolites such as amino acids and catechins contribute to forming taste of LYT. • Variations in non-volatiles and volatiles among different LYTs were elaborated. Roasting is essential for processing large-leaf yellow tea (LYT). However, the effect of the roasting on the metabolic and sensory profiles of LYT remains unknown. Herein, the metabolomics and sensory quality of LYT at five roasting degrees were evaluated by liquid/gas chromatography mass spectrometry and quantitative descriptive analysis. A higher degree of roasting resulted in a significantly stronger crispy rice, fried rice, and smoky-burnt aroma (p < 0.05), which is closely associated with heterocyclic compound accumulation (concentrations: 6.47 ± 0.27 – 1065.00 ± 5.58 µg/g). Amino acids, catechins, flavonoid glycosides and N -ethyl-2-pyrrolidone-substituted flavan-3-ol varied with roasting degree. The enhancement of crispy-rice and burnt flavor coupled with the reduction of bitterness and astringency. Correlations analysis revealed the essential compounds responsible for roasting degree, including 2,3-diethyl-5-methylpyrazine, hexanal, isoleucine, N -ethyl-2-pyrrolidone-substituted flavan-3-ol (EPSF), and others. These findings provide a theoretical basis for improving the specific flavors of LYT. [ABSTRACT FROM AUTHOR]

[Display omitted] • Over-fired drying methods affect the aroma quality of Lu'an Guapian (LAGP). • (E)- β -ionone is the most crucial aroma active compound in LAGP. • Pulley charcoal drying significantly enhanced the floral and fruity aroma of LAGP. Over-fired drying, a crucial process in the production of Lu'an Guapian (LAGP) tea, greatly enriches the tea's aroma. In this study, the aroma compounds of LAGP tea processed through pulley charcoal drying (PCD), roller drying (RD), roller-conveyor drying (RCD), and hot air drying (HD) were analyzed using gas chromatography–mass spectrometry. A subsequent analysis of aroma extraction dilution analysis and odor activity values revealed that (E)- β -ionone, dimethyl sulfide, (E,E)-2,4-heptadienal, geraniol, linalool, benzeneacetaldehyde, coumarin, 2-ethyl-3,5-dimethyl-pyrazine, indole, hexanal, (Z)-jasmone, and (Z)-3-hexen-1-ol were the key contributors to the samples' aroma variation. Moreover, a quantitative descriptive analysis and aroma recombination and omission experiments analysis revealed that (E)- β -ionone is the most critical contributor to the formation of floral aroma in tea processed using PCD, whereas (E,E)-2,4-heptadienal is responsible for the more pronounced fresh aroma in tea processed using HD. In addition, 2-ethyl-3,5-dimethyl-pyrazine contributes to the formation of a roasted aroma in tea processed using RD and RCD. The study results provide a theoretical basis for choosing the processing method, especially for drying, to obtain high-quality LAGP tea. [ABSTRACT FROM AUTHOR]

Objectives: Dysregulation of immune cells in the tumor microenvironment is a hallmark of head and neck squamous cell carcinoma (HNSCC). Increased infiltration of pDCs has been reported in the microenvironment of HNSCC. However, the precise immunological role of pDC and the therapeutic effects of pDC depletion in HNSCC need to be further investigated.Materials and Methods: CD317 antibodies were applied for depleting pDCs in an immunocompetent transgenic HNSCC mouse model. Tumor volume was monitored. Flow cytometric analysis was conducted for studying the immune profile changes after pDC depletion. In addition, immunohistochemical staining was carried out in a human HNSCC tissue microarray for detecting the infiltration of pDCs. We also analyzed the survival implication of pDCs and its correlation with other immune related markers in human HNSCC.Results: pDC depletion in the transgenic HNSCC mouse model significantly delayed tumor growth. After pDCs were depleted, T cells were markedly revitalized, and the proportions of regulatory T cells (Tregs) and monocytic myeloid-derived suppressor cells (MDSCs) were decreased. In human HNSCC microenvironment, pDC infiltration was upregulated and its high infiltration conferred a poor prognosis. Moreover, pDC infiltration was closely correlated with the expression of Foxp-3, PD-1, TIM-3, and LAG-3.Conclusion: Our findings demonstrated that pDCs play a negative immunomodulatory role in HNSCC and may present as a target for effective immunotherapy. [ABSTRACT FROM AUTHOR]

Abstract Expression of the family with sequence similarity 3 member C (FAM3C) is necessary for the epithelial-mesenchymal transition (EMT). However, the expression level and clinicopathological significance of FAM3C in oral squamous cell carcinoma (OSCC) has not been thoroughly elucidated to date. We performed immunohistochemical staining on human OSCC specimens with FAM3C, co-inhibitory immune checkpoints, EMT markers, and cancer stem cells (CSCs) markers to analyze the expression levels and clinicopathological features of FAM3C in OSCC. There were 210 primary OSCC specimens, 69 oral epithelial dysplasia and 42 normal oral mucosae in our human OSCC tissue microarrays cohort. We observed that FAM3C expression was upregulated in OSCC compared with normal mucosa and epithelial dysplasia (P < 0.001). Moreover, patients with higher FAM3C expression levels had a worse prognosis than those with lower expression levels (P < 0.05). Also, FAM3C expression was positively correlated with the immune checkpoints PD-L1, VISTA, and B7-H4, the EMT marker Slug and the CSC markers SOX2 and ALDH1. In conclusion, these findings suggested that overexpression of FAM3C in human OSCC may predict a poor prognosis for OSCC patients. [ABSTRACT FROM AUTHOR]

Phenolic compounds, such as flavanols, flavones, flavonols, anthocyanins, and phenolic acids, contribute to a plant’s adaptation to their ecological niches. These compounds serve as attractants of organisms beneficial to the plants or as defence against other biotic and abiotic factors during the plant evolution. In this paper, the accumulation patterns of phenolic compounds in the eight evergreen woody core eudicots indicated divergent and convergent evolution of plant secondary metabolites. The results indicated some phenolic acids and flavonols were distributed in all the studied eight evergreen woody plants, within Oleaceae, Theaceae, Caprifoliaceae and Celastraceae, with different accumulation profiles. The flavan-3-ols, monomeric catechins, and polymeric proanthocyanidins, were undetectable in Osmanthus fragrans , Ligustrum lucidum, and Fraxinus mariesii of Oleaceae, but highly accumulated in the other five species, especially in Camellia sinensis of Theaceae. It indicated Camellia sinensis evolved great ecological adaptive capacity to prevent herbivores, insect pests, and microbial pathogens. [ABSTRACT FROM AUTHOR]

[Display omitted] • IDA was composed of phenylboronic acids, pyrocatechol violet, and alizarin red S. • TP, TC, and EGCG were key quality indicators of black tea fermentation. • SVM model achieved accurate qualitative evaluation of fermentation degrees. • SCARS-SVR model achieved accurate prediction of TP, TC, and EGCG. • In-situ quality monitoring of black tea fermentation was realized. Herein, a new indicator-displacement array (IDA) sensor was developed for the quality evaluation of black tea fermentation. On the principle of the reversible covalent binding of phenylboronic acid and catechol, phenylboronic acids were selected as acceptors for targeted binding to polyphenols. Pyrocatechol violet and alizarin red S were used as indicators of the reaction. The IDA sensors have sensitive differential responses to fermented tea samples, achieving an assessment of the fermentation degree with accuracies of 80.39–88.00% by support vector machine (SVM). In addition, the key polyphenol components of the fermentation process were accurately predicted by the IDA and SVM regression with ratio of prediction to deviation values of 1.55–1.72, 2.03–2.21, and 2.03–2.08 for total polyphenols, total catechins, and epigallocatechin-3-O-gallate, respectively. In conclusion, the developed IDA sensor is capable of the in-situ quality monitoring of black tea fermentation, with the advantages being cost-effectiveness, sensitivity, and rapidity. [ABSTRACT FROM AUTHOR]

Fixation is the key step of green tea processing, usually with moisture content as the quality evaluation indicator. Near-infrared (NIR) spectroscopy has been widely used in tea moisture detection but is mostly realized in the laboratory, and online detection in tea processing is limited. This study explores the possibility of calibration transfer from lab-based hyperspectral imaging (HSI) to online NIR to enable the rapid detection of moisture during the fixation step. Raw spectral data were preprocessed, and direct standardization (DS) and partial least-squares regression (PLS) were used for data calibration and modeling, respectively. The results showed that there were observable differences in the spectral data of the same sample obtained by different instruments. The prediction model based on HSI failed to be transferred directly to the online NIR and has a large root mean square error of prediction (RMSEP) value. Spectral preprocessing with a standard normal variate (SNV) transformation reduced the differences between the instruments. When 40 standard samples were used, the established transferable SNV-DS-PLS model based on HSI achieved the optimal prediction performance with a correlation coefficient of prediction (Rp), RMSEP, and ratio of prediction to deviation (RPD) of 0.94, 2.24%, and 2.76, respectively, for the 50 validated tea samples obtained from online NIR. In conclusion, the model transfer across instruments was successfully realized, and tea moisture detection was brought from the laboratory to the tea factory, which provided a reference model for online moisture detection for other agricultural products. • Calibration transfer from HSI to online NIR for tea processing was optimized. • Online detection of moisture during green tea fixation was achieved. • Model built based on HSI fails to be transferred directly to the online NIR. • Transferable SNV-DS-PLS model gave the optimal performance for moisture. [ABSTRACT FROM AUTHOR]

• Data of fermented tea samples was collected at-line by an industrial camera. • Catechins, theaflavins and chlorophylls were chosen as key quality indicators. • Correlations between color variables and quality indicators were established. • Spatial and temporal distribution of indicators was mapped and visualized. Fermentation is a key black tea processing step and makes an important contribution to quality formation. Current approaches to fermentation monitoring are costly or laboratory-based. Here, we first evaluated the potential of at-line computer vision for detecting fermentation quality in a tea factory. A self-built industrial camera was used to collect tea samples at various fermentation durations. The correlations of color variables that were extracted from the images with key quality indicators in the tea samples were verified. Subsequently, partial least-squares regression models based on the color variables showed high prediction accuracy with residual prediction deviation values of 4.13, 3.53, and 3.39 for catechins, theaflavins and chlorophylls, respectively. Finally, the spatial and temporal distributions of indicators during fermentation were mapped to visualize the fermentation quality. This study realized low-cost, at-line and real-time detection for black tea fermentation, which provides technical support for the industrial and intelligent production of black tea. [ABSTRACT FROM AUTHOR]

• Different withering methods affect the aroma quality of Keemun black tea. • Sun withering significantly enhanced the floral and fruity of Keemun black tea. • Methional, geraniol and linalool are the most active-aroma in Keemum black tea. • A more comprehensive profile of Keemun aroma was obtained. Withering is a key process that affects the aroma of Keemun black tea (KBT). In this study, the aroma composition of KBT through natural withering, sun withering, and warm-air withering was analysed using gas chromatography–mass spectrometry. The results revealed significant differences in the three samples. Gas chromatography–olfactometry and aroma extract dilution analysis were performed with screening through a relative odour activity value (rOAV) > 1. In total, 11 aroma-active compounds (geraniol, (Z)-4-heptenal, 1-octen-3-ol, (E)- β -ionone, 3-methylbutanal, linalool, β -damascenone, (E , E)-2,4-decadienal, methional, (E , E)-2,4-nonadienal, and (E)-2-nonenal) were found to be responsible for the differences in aroma caused by different withering methods. Linalool (rOAV, 161) and geraniol (rOAV, 785) were responsible for the higher flowery and fruity aromas when sun withering was applied, whereas methional (rOAV, 124) contributed to the intense roasty aroma when warm-air withering was employed. Moreover, our results were verified by quantitative descriptive analysis and addition experiments. [ABSTRACT FROM AUTHOR]

[Display omitted] • We evaluated the genes involved in catechins biosynthesis in C. sinensis. • In total, 47,717 unigenes were obtained from two cultivars of C. sinensis. • KEGG database analysis identified 13 key enzymes involved in catechins biosynthesis. • The structures of LAR and ANR were spatially modeled. • Our findings established a basis for further studies of catechins biosynthesis. Camellia sinensis (L.) O. Kuntze is used to produce tea, a beverage consumed worldwide. Catechins are major medically active components of C. sinensis and can be used clinically to treat hyperglycaemia, hypertension, and cancer. In this study, we aimed to identify the genes involved in catechins biosynthesis. To this end, we analysed transcriptome data from two different cultivars of C. sinensis using DNBSEQ technology. In total, 47,717 unigenes were obtained from two cultivars of C. sinensis , of which 9429 were predicted as new unigenes. In our analyses of the Kyoto Encyclopedia of Genes and Genomes database, 212 unigenes encoding 13 key enzymes involved in catechins biosynthesis were identified; the structures of leucoanthocyanidin reductase and anthocyanidin reductase were spatially modelled. Some of these key enzymes were verified by real-time quantitative polymerase chain reaction, and multiple genes encoding plant resistance proteins or transcription factors were identified and analysed. Furthermore, two microRNAs involved in the regulation of catechins biosynthesis were explored. Differentially expressed genes involved in the flavonoid biosynthesis pathway were identified from pairwise comparisons of genes from different cultivars of tea plants. Overall, our findings expanded the number of publicly available transcript datasets for this valuable plant species and identified candidate genes related to the biosynthesis of C. sinensis catechins, thereby establishing a foundation for further in-depth studies of catechins biosynthesis in varieties or cultivars of C. sinensis. [ABSTRACT FROM AUTHOR]

• An ecologically insensitive variegated tea plant was studied in this research. • The component, tissue structure, gene and protein expressions were analyzed. • Reduced catechins and increased amino acids were found in variegated tea leaves. • Related genes and proteins were down-regulated in flavonoid biosynthetic pathway. • The high expression of CLH1, showed an active chlorophyll degradation in variegated leaves. Globally, tea plant (Camellia sinensis (L.) O. Kuntze) is a crucial commercial crop. In this study, a variegated tea plant identified in Huangshan, China. The variegated and residual normal leaves were used as the research material. The variegated leaves of the plant were ecologically insensitive. The components, tissue structure, gene expression patterns, and protein expression profiles of the variegated tea plant were analyzed. Ultrastructural analysis of the variegated leaves revealed that the chloroplasts of the leaves were abnormally developed, with no obvious thylakoids. Compared with normal leaves, the albino leaves had lower total catechins content and higher total free amino acid content. Through RNA sequencing and proteomic analysis, chlorophyll biosynthesis and degradation, photosynthesis, chloroplast development, and flavonoid biosynthesis of the variegated leaves were affected. The less chlorophyll content in the variegated tea leaves could probably attributed to the destruction of chloroplast structure. Besides, the relatively high expression and enzyme activity of CLH, showed an active chlorophyll degradation; the lower expression of Lhcb1, Lhcb3 ; and POR in chlorophyll synthesis, might be related to the low chlorophyll in variegated leaves. In terms of flavonoid biosynthesis, expression of the related genes was down-regulated and the target protein content of ANR, CHI) was also reduced. These results may provide insight into the catechins mechanism of such variegated phenotypes. [ABSTRACT FROM AUTHOR]

• Low-cost, portable instruments were used to evaluate the tea processing quality. • A satisfactory classification rate (89.19%) was achieved using data fusion. • Quantitative model showed high prediction performance for the theaflavin content. • Our results provide templates for at-line monitoring of tea processing quality. Intelligent identification of black tea fermentation quality is becoming a bottleneck to industrial automation. This study presents at-line rapid detection of black tea fermentation quality at industrial scale based on low-cost micro-near-infrared spectroscopy (NIRS) and laboratory-made computer vision system (CVS). High-performance liquid chromatography and a spectrophotometer were used for determining the content of catechins and theaflavins, and the color of tea samples, respectively. Hierarchical cluster analysis combined with sensory evaluation was used to group samples through different fermentation degrees. A principal component analysis–support vector machine (SVM) model was developed to discriminate the black tea fermentation degree using color, spectral, and data fusion information; high accuracy (calibration = 95.89%, prediction = 89.19%) was achieved using mid-level data fusion. In addition, SVM model for theaflavins content prediction was established. The results indicated that the micro-NIRS combined with CVS proved a portable and low-cost tool for evaluating the black tea fermentation quality. [ABSTRACT FROM AUTHOR]

[Display omitted] • Pu'er tea (RPT) volatiles were identified by metabolomics and molecular sensory science. • Potential markers of RPTs stored in dry-cold and wet-hot environments were found. • Markers may explain the corresponding floral, sweet, fruit and woody, stale aromas. The aroma profile of raw pu'er tea (RPT) depends on its storage duration (2–10 years) and storage conditions (wet-hot or dry-cold environment). We analyzed the major odorants of RPT samples by performing metabolomic analysis and by using the molecular sensory science approach. Under dry-cold storage conditions, tea leaves had more carotenoid derivatives, glycoside-derived volatiles, and phenolic volatiles, resulting in "fresh," "floral," and "sweet" aroma. Under wet-hot storage conditions, tea leaves had more methoxybenzenes, which contributed considerably to their "stale" and "woody" aroma. We identified 11 and 4 compounds as the odor markers of RPTs when stored in dry-cold and wet-hot environments, respectively. Our findings provide a scientific basis for optimal storage that yields the desired aroma profile. [ABSTRACT FROM AUTHOR]