Xyloglucan endotransglucosylase/hydrolases (XTHs) are key cell-wall-remodeling enzymes that mediate xyloglucan modification, cell expansion, and organ elongation, yet the composition and variation in the XTH gene family across tea accessions remain unclear. In this study, we systematically identified and comparatively analyzed the XTH gene family across the genomes of nine tea accessions, yielding 477 putative XTH genes. Phylogenetic, conserved-motif, protein-domain, and conserved catalytic-motif analyses indicated that the major structural features of tea XTH proteins are broadly conserved, whereas orthogroup-based presence-absence variation (PAV) analysis revealed core, variable, and accession-specific components within the family. Using transcriptomic expression profiles across eight tissues, we selected eight CsXTH genes for internode expression analysis. Reverse transcription quantitative PCR (RT-qPCR) showed that all eight genes were expressed at significantly higher levels in the third internode (I3) than in the second internode (I2) in 'Longjing 43' (LJ43), and CsXTH27 retained the same internode-associated expression pattern in 'Baihaozao' (BHZ) and 'Zhongcha 108' (ZC108), supporting its selection for functional analysis. Transient overexpression of CsXTH27 significantly increased the lengths of I2, I3, and I4, as well as the total length of I1-I4, compared with the empty-vector control. This phenotype was accompanied by significantly increased XTH protein content in stems and an apparent tendency toward larger pith parenchyma cell profiles. Overall, these findings reveal both structural conservation and accession-level variation in the tea XTH gene family and provide preliminary functional evidence linking CsXTH27 to shoot internode elongation.

IntroductionGibberellin oxidases (GAoxs) are key enzymes involved in maintaining gibberellin (GA) homeostasis and therefore play important roles in regulating plant architecture. However, the GAox genes associated with branch angle and internode elongation in tea plants (Camellia sinensis) remain largely uncharacterized.MethodsIn this study, 33 CsGAox genes were identified in the genome of the tea cultivar `Longjing 43' and classified into four subfamilies. Comparative genomic analysis across eight Camellia genomes was performed, and phenotypic measurements were integrated with endogenous GA quantification, transcriptome profiling, qRT-PCR analysis, and exogenous GA₃ treatment.ResultsWhole-genome or segmental duplication contributed substantially to the expansion of the CsGAox family, with duplicated gene pairs in `Longjing 43' predominantly undergoing purifying selection. The levels of GA₁, GA₉, and GA₂₀ were higher in the lateral buds of the draped cultivar than in those of the upright cultivars and were positively correlated with branch angle. CsGA20ox4.3 expression was positively associated with branch angle and the levels of those GAs, whereas CsGA2ox5.3 exhibited the opposite relationships. Exogenous GA₃ application significantly increased branch angle and was accompanied by the upregulation of CsGA20ox4.3 and CsGA20ox.un3 and the downregulation of CsGA2ox5.3. Integrated analyses across cultivars and developmental stages further showed that CsGA20ox4.3 and CsGA3ox3.3 were positively associated with internode elongation, whereasCsGA2ox1.1, CsGA2ox5.2, and CsGA2ox.un1 generally exhibited negative associations. DiscussionThese findings identify candidate CsGAox genes associated with branch angle and internode elongation, providing a basis for future functional studies and further evaluation in tea plant architecture breeding.

Exploiting mechanical picking of fresh leaves is an urgent task in the tea industry. The internode length of new shoots is one of the key traits determining the suitability of tea plants for mechanical picking. In this study, we explored the mechanisms regulating tea internode elongation through transcriptome sequencing and endogenous hormone analysis in two cultivars with different internode length. The results indicated that internode elongation is associated with the increased parenchyma cell diameter in the internode. One CsDELLA gene (CsDELLA2), three CsMYC transcription factors (TFs) (CsMYC1.2, CsMYC1.3, and CsAMS.2), two CsJAZ TFs (CsJAZ1 and CsJAZ3), and three secondary cell wall-related genes (CsEXP1, CsCESA1 and CsXTH1) have been identified as potential candidate genes. These results provide candidate genes for obtaining tea plants with longer internodes which are suitable for mechanical harvesting.

Drought stress severely constrains global tea production. Exogenous glycine betaine (GB) application significantly enhances drought tolerance in tea plants (Camellia sinensis), with a markedly stronger effect in drought-sensitive cultivars than in tolerant ones. Through genome-wide ALDH family analysis, we identified CsBADH as the sole functional betaine aldehyde dehydrogenase responsible for GB biosynthesis in tea, and recombinant enzyme assays confirmed its catalytic activity. Drought stress induced CsBADH expression, and its functional importance was confirmed through heterologous overexpression in Arabidopsis and tobacco, as well as through transient overexpression and antisense oligonucleotide-mediated silencing in tea plants. Collectively, these experiments demonstrated that CsBADH is required for drought-induced GB accumulation and tolerance. Mechanistically, CsBADH overexpression reduced oxidative damage and maintained cellular osmotic homeostasis, as evidenced by decreased malondialdehyde (MDA) accumulation, elevated proline content and peroxidase (POD) activity, and preserved photosynthetic efficiency (Fv/Fm). Importantly, foliar GB application did not significantly alter the catechin quality index (CQI) in fresh leaves, as determined by UPLC, nor did it adversely affect tea volatile profiles or organoleptic quality, as confirmed by electronic nose and sensory evaluations. Collectively, these findings establish CsBADH-mediated GB biosynthesis as a critical drought-tolerant mechanism in tea and support exogenous GB application as an effective, safe, and quality-preserving strategy to mitigate drought damage, particularly in drought-sensitive cultivars.

Tea blending technology is based on finished tea. Blending fresh leaves during processing has not been proposed and investigated anywhere. This study investigates the impact of blending fresh leaves from different varieties on the flavor quality of black tea. The main taste components, including catechins, theaflavins, and free amino acids, were analyzed using HPLC, while the volatile components were analyzed using GC-MS. The results show that adding fresh Jinguanyin or Jinxuan leaves to Fudingdabai can regulate the ratio of esterified to non-esterified catechins, increase the content of theaflavins and amino acids, and positively impact the strength and freshness of the black tea. The sensory evaluation results show that the taste scores of FJG (black tea made from the blend of fresh Fudingdabai and Jinguanyin tea leaves) (92.14 ± 0.41 b) and FJX (black tea made from the blend of fresh Fudingdabai and Jinxuan tea leaves) (93.80 ± 0.19 a) are significantly higher than those of Fudingdabai (90.05 ± 0.31 d), Jinguanyin (86.10 ± 0.45 e), and Jinxuan (91.03 ± 0.26 c). Furthermore, adding fresh Jinguanyin or Jinxuan leaves to Fudingdabai can also enhance the floral compounds in the black tea, specifically phenylacetaldehyde, linalool, benzyl alcohol, and oxidized linalool (linalool-type pyran), which make important contributions to the floral aroma of the black tea. Conclusions: Blending fresh leaves for processing can enhance the sensory quality of black tea. This work proposes new insights and methods to enhance black tea sensory quality via the blending of fresh tea leaves with different varieties during processing.

Cold stress significantly limits the growth and yield of tea plants (Camellia sinensis (L.) O. Kuntze), particularly in northern China, may lead to huge economic losses. Glycine betaine (GB), an osmotic regulator, is widely applied in crop resistance to abiotic stress. This study investigates the role of GB and its biosynthetic enzyme CsBADH in enhancing cold tolerance in tea plants. Two cultivars, 'Shuchazao' (cold-resistant) and 'Baiye 1' (cold-sensitive), were subjected to low temperature stress (0 degrees C). GB accumulation was measured, revealing that 'Shuchazao' exhibited 1.4-fold higher GB levels than 'Baiye 1 ', suggesting a link between higher GB accumulation and cold tolerance. Exogenous GB treatment improved cold resistance, especially in the cold-sensitive cultivar 'Baiye 1'. The CsBADH gene, a key enzyme in GB biosynthesis, was cloned and expressed in Escherichia coli, confirming its activity. Transgenic Arabidopsis thaliana, Nicotiana tabacum, and C. sinensis plants overexpressing CsBADH showed increased GB levels (1.5- to 2.4-fold), proline content, peroxidase (POD) activities, and enhanced cold tolerance, while silencing CsBADH decreased GB accumulation and cold resistance. These findings demonstrate that CsBADH plays a critical role in cold stress response by promoting GB accumulation, offering potential strategies for improving the resilience of tea and other leaf crops to cold stress.

Benzoates, particularly salicylic acid (SA) and its derivatives, play critical roles in plant immune responses and basal defense through hydroxylation and glycosylation. Anthracnose is one of the most common and devastating diseases in tea plants (Camellia sinensis). However, the role of SA and its derivatives in tea plant immunity and resistance to anthracnose remains largely unexplored. In the present study, we identified and characterized a glycosyltransferase, CsUGT74B5, which was significantly downregulated in tea seedlings upon anthracnose infection. CsUGT74B5 was preferentially expressed in mature leaves and stem, and responded rapidly to exogenous SA treatment. Phylogenetic analysis suggested CsUGT74B5 might possess the catalytic activity toward benzoates. Enzymatic assays and molecular docking demonstrated recombinant CsUGT74B5 specifically glycosylated at the ortho hydroxyl groups of SA and 2, 6-dihydroxybenzoic acid (2, 6-DHBA), but did not glycosylate 2, 3-DHBA, 2, 5-DHBA, or other substrates in vitro. Overexpression of CsUGT74B5 in Arabidopsis thaliana and tobacco (Nicotiana tabacum) reduced SA level while promoting the accumulation of SA 2-O-β-D-glucoside (SAG), further validating the in vivo function of CsUGT74B5. Moreover, transient overexpression of CsUGT74B5 in two tea plant cultivars increased their sensitivity to anthracnose and accelerated lesion development, which was attributed to decreased SA levels. Overall, our finding demonstrated that CsUGT74B5-mediated biosynthesis of SAG regulated tea plant immunity against anthracnose by fine-tuning free SA levels, providing new progress into the immunity response of tea plants.

To protect tea plant (Camellia sinensis (L.) O. Kuntze) from freezing injury, plastic greenhouse covering is widely used in northern tea areas of China. Currently, there was few researches about the effect of greenhouse covering on tea quality. Our results showed greenhouse covering increased tea yield, changed leaf phenotype and decreased green tea quality. Further analysis revealed greenhouse increased the content of soluble sugars and decreased the content of EGCG and 14 amino acids. Besides, there were 223 differential volatile components were identified in green tea produced by fresh leaves with plastic greenhouse covering (GT) and green tea produced by fresh leaves without plastic greenhouse covering (TT). 81 key aroma components were contributors to the bean-like aroma of TT. 98 key aroma components contributed to the clean aroma of GT. Based on these results, the flavor wheels were constructed, providing a visual presentation of flavor between TT and GT.

Plants would encounter various biotic and abiotic stresses during the growth and development. WRKY transcription factors (TFs) as plant-specific TFs, play an important role in responding to various adverse circumstances. Despite some advances were achieved in functional studies of WRKY TFs in tea plants, systematic analysis of the involvement of CsWRKY TFs when facing cold, salt, drought stresses and pathogen and insect attack was lacked. In present study, a total of 78 CsWRKY TFs were identified following the genomic and transcript databases. The expression patterns of CsWRKYs in various organs of tea plants and the expression profiles in response to biotic and abiotic stresses were investigated by examining representative RNA-seq data. Moreover, the effects of hormone treatments (SA and MeJA) on the transcription levels of WRKY TFs were also investigated. The phylogenetic tree of CsWRKY TFs from different species indicated the functional diversity of WRKY TFs was not closely related to their protein classification. Concurrently, CsWRKY70-2 TF was identified as a positive regulator in response to drought stress. This study provided solid and valuable information, helping us better understand the functional diversity of CsWRKY TFs, and laid the foundation for further research on the function of key WRKY genes in tea plants.

BACKGROUND:The tea plant (Camellia sinensis (L.) O. Kuntze) is one of the most economically important woody crops. Plastic greenhouse covering cultivation has been widely used in tea areas of northern China. Chlorophyll is not only the crucial pigment for green tea, but also plays an important role in the growth and development of tea plants. Currently, little is known about the effect of plastic greenhouse covering cultivation on chlorophyll in tea leaves.RESULTS:To investigate the effect of plastic greenhouse covering cultivation on chlorophyll in tea leaves, color difference values, chlorophyll contents, gene expression, enzyme activities and photosynthetic parameters were analyzed in our study. Sensory evaluation showed the color of appearance, liquor and infused leaves of greenhouse tea was greener than field tea. Color difference analysis for tea liquor revealed that the value of ∆L, ∆b and b/a of greenhouse tea was significantly higher than field tea. Significant increase in chlorophyll content, intracellular CO2, stomatal conductance, transpiration rate, and net photosynthetic rate was observed in greenhouse tea leaves. The gene expression and activities of chlorophyll-metabolism-related enzymes in tea leaves were also activated by greenhouse covering.CONCLUSION:The higher contents of chlorophyll a, chlorophyll b and total chlorophyll in greenhouse tea samples were primarily due to higher gene expression and activities of chlorophyll-metabolism-related enzymes especially, chlorophyll a synthetase (chlG), pheophorbide a oxygenase (PAO) and chlorophyllide a oxygenase (CAO) in tea leaves covered by greenhouse. In general, our results revealed the molecular basis of chlorophyll metabolism in tea leaves caused by plastic greenhouse covering cultivation, which had great significance in production of greenhouse tea.

该研究以曼地亚红豆杉鲜叶(T.media Fresh Leaves,TFL)为材料,通过杀青、揉捻、干燥制成红豆杉茶叶(T.media Tea,TT).运用超高效液相色谱串联质谱(UPLC-MS/MS)分析比较曼地亚红豆杉鲜叶加工前后的差异化合物.在TFL和TT中共鉴定到796种化合物,TFL中有777种化合物,TT中有768种化合物.根据PCA结合OPLS-DA筛选出差异化合物330种,其中氨基酸、脂质、黄酮、酚酸等255种化合物在TFL中含量高,有机酸等105种化合物在TT中含量高.TFL和TT的关键差异化合物有11种,包括柠康酸、3,5-二羟基-3-甲基戊酸、(2'S3'R)-5-(N,N二甲基-3'-苯基异丝氨酰)-红豆杉三烯A、1,3,5-苯三酚、澳大利亚紫杉碱、3-羟基吡啶、吡咯-2-羧酸在 TT 中含量较高;苯甲醛、橙皮素-7-O-葡萄糖苷、9-过氧-10E,12Z-十八碳二烯酸、木犀草素-7-O-(6''-咖啡酰)鼠李糖苷在TFL中含量较高.该研究将为红豆杉鲜叶的开发利用提供理论依据.

BACKGROUND:Chestnut-like aroma is one of the unique qualities of Chinese green tea and has become an important factor influencing consumer decisions. However, the chemical formation mechanism of chestnut-like aroma during green tea processing remains unclear. In this study, the dynamic changes of key components contributing to chestnut-like aroma and their precursors were analyzed in fresh leaves, fixation leaves, first baking tea leaves, and green tea.RESULTS:The thermal process had an important effect on volatile components in tea leaves, causing a significant decrease of alcohols and esters and a significant increase of ketones, acids, phenols, and sulfur compounds. Furthermore, 31 volatiles were identified as the key odorants responsible for chestnut-like aroma of green tea, including dimethyl sulfide, methyl isobutenyl ketone, 2-methylbutanal, 2,4-dimethylstyrene, d-limonene, methyl 2-methylvalerate, linalool, decanal, longifolene, phenylethyl alcohol, l-α-terpineol, jasmone, and so on. And the majority of these odorants were only formed in the drying stage. Additionally, isoleucine, theanine, methionine, and glucose were found to be involved in the formation of chestnut-like aroma of green tea.CONCLUSION:The drying process played a vital important role in the formation of chestnut-like aroma of green tea. © 2022 Society of Chemical Industry.

Taxaceae, is a class of dioecious and evergreen plant with substantial economic and ecology value. At present many phytochemical analyses have been performed in Taxus plants. And various biological constituents have been isolated from various Taxus species. However, the difference of compounds and antioxidant capacity of different tissues of T. media is not clear. In the present study, we investigated the metabolites and antioxidant activity of four tissues of T. media, including T. media bark (TB), T. media fresh leaves (TFL), T. media seeds (TS), T. media aril (TA). In total, 808 compounds, covering 11 subclasses, were identified by using UPLC-MS/MS. Paclitaxel, the most popular anticancer compound, was found to accumulate most in TS, followed by TB, TFL and TA in order. Further analysis found that 70 key differential metabolites with VIP > 1.0 and p < 0.05, covering 8 subclasses, were screened as the key differential metabolites in four tissues. The characteristic compounds of TFL mainly included flavonoids and tanninsis. Alkaloids and phenolic acids were major characteristic compounds of TS and TB respectively. Amino acids and derivatives, organic acids, saccharides and lipids were the major characteristic compounds of TA. Additionally, based on FRAP and ABTS method, TS and TFL exhibited higher antioxidant activity than TB and TA. There was significant difference in metabolite content among different tissues of T. media. TFL and TS had higher metabolites and antioxidant capacity than other tissues, indicating that TFL and TS were more suitable for the development and utilization of T. media in foods and drinks.

Salicylic acid (SA) is an important plant hormone and signal required for establishing resistance to diverse pathogens and plant diseases. The abundant polyphenols in tea plants also defend plants from biotic and abiotic stresses. However, whether exogenous SA would increase the resistance of tea plants to adversity and the relationship between SA and polyphenols are still poorly understood. Here, we carried out SA treatment on tea seedlings and performed transcriptome sequencing. SA treatment inhibited the phenylpropanoid and flavonoid metabolic pathways but promoted the lignin metabolic pathways. The increased accumulation of lignin in tea leaves after treating with SA indicated that lignin might coordinate SA, enhance, and improve plant defense and disease resistance. Simultaneously, an SA-inducible flavonoid glucosyltransferase (CsUGT0554) specifically involved in 7-OH site glycosylation was characterized in vitro. These results provided valuable information about the effects of SA on tea seedlings and the molecular basis for SA-mediated immune responses.

Matcha has a unique aroma of seaweed-like, which is popular with Chinese consumers. In order to effectively understand and use matcha for drinks and tea products, we roundly analyzed the variation of main quality components of 11 matcha samples from different regions in the Chinese market. Most of matcha samples had lower ratio of tea polyphenols to amino acids (RTA), and the RTA of 9 samples of matcha was less than 10, which is beneficial to the formation of fresh and mellow taste of matcha. The total volatile compounds concentrations by HS-SPME were 1563.59 ~ 2754.09 mg/L, among which terpenoids, esters and alcohols were the top three volatile components. The total volatile compounds concentrations by SAFE was 1009.21 ~ 1661.98 mg/L, among which terpenoids, heterocyclic compounds and esters ranked the top three. The 147 volatile components with high concentration (>1 mg/L) and no difference between samples are the common odorants to the 11 samples of matcha. The 108 distinct odorants had differences among the matcha samples, which were important substances leading to the different aroma characteristics. Hierarchical cluster analysis (HCA) and orthogonal partial least squares discriminant analysis (OPLS-DA) showed that 11 samples of matcha were well clustered according to different components. Japanese matcha (MT, MY, ML, MR, MJ) could be clustered into two categories. The aroma composition of Guizhou matcha (GM1, GM2) was similar to that of Japanese matcha, 45 volatile components (decanal, pyrazine, 3,5-diethyl-2-methyl-, 1-hexadecanol, etc. were its characteristic aroma components. The aroma characteristics of Shandong matcha and Japanese matcha (ML, MR, MJ) were similar, 15 volatile components (γ-terpinene, myrtenol, cis-3-hexenyl valerate, etc.) were its characteristic aroma components. While Jiangsu matcha and Zhejiang matcha have similar aroma characteristics due to 225 characteristic aroma components (coumarin, furan, 2-pentyl-, etc). In short, the difference of volatile components formed the regional flavor characteristics of matcha. This study clarified the compound basis of the flavor difference of matcha from different regions in the Chinese market, and provided a theoretical basis for the selection and application of matcha in drinks and tea products.

儿茶素类化合物,主要包括单体儿茶素和聚合态儿茶素,是茶树(Camellia sinensis)多酚主要组成部分,是绿茶"茶味"决定性成分.茶树儿茶素类化合物合成与积累具有显著的组织器官特异性,鲜叶中主要积累单体儿茶素,根中以积累聚合态儿茶素为主.类黄酮代谢途径下游的无色花青素还原酶(LAR)和花青素还原酶(ANR)是决定茶树儿茶素类化合物类型的关键酶类.本文主要综述了茶树儿茶素类化合物合成、积累、转录调控研究进展,重点关注LAR、ANR以及无色花青素双加氧酶(LODX)功能和基因转录调控的最新研究进展,并对儿茶素合成途径待解决问题提出了自己的观点.

This study investigates the volatile compounds of green tea produced with different leaves from spring, summer, and autumn in high−latitude region. A total of 95 volatile compounds were identified by gas chromatography–mass spectrometry (GC–MS). Spring, summer and autumn green tea contained 68, 72 and 82 volatile compounds, respectively. Principal component analysis (PCA), partial least squares−discrimination analysis (PLS−DA), and hierarchical cluster analysis (HCA) classified the samples and showed the difference. And 32 key characteristic components were screened out based on variable importance in the projection (VIP) values higher than 1.0. The characteristic volatile compounds of spring green tea including 18 components, such as geranylacetone, phenethyl alcohol, geraniol, β−ionone, jasmone, 1−octen−3−ol and longifolene. 13 components such as 2−methylfuran, indole, 1−octanol, D−limonene and ethanethiol were the key compounds in summer green tea. And 2,4,6−trimethylstyrene was the major differential volatile compounds in autumn green tea. The results increase our knowledge of green tea in different seasons and provide a theoretical basis for production control of green tea.

Brassinosteroid (BR), a kind of polyhydroxylated steroid hormone, plays an important role in physiological and biochemical processes in plants. Studies were mainly focused on BR signaling and its exogenous spraying to help enhance crop yields. Few research studies are centered on the accumulation pattern of BR and its mechanism. Yet, it is crucial to unlock the mystery of the function of BR and its cross action with other hormones. Tea (Camellia sinensis (L.) O. Kuntze) is one of the important economic crops in some countries, and new shoots are the raw materials for the preparation of various tea products. Different concentrations of exogenous BR were reported to have different effects on growth and development. New shoots of tea plants can thus be considered a valuable research object to study the accumulation pattern of BR. In this study, the quantity of five BR components (brassinolide, 28-norbrassinolide, 28-homobrassinolide, castasterone, and 28-norcastasterone) in different tissues of tea plants, including buds (Bud), different maturity of leaves (L1, L2), and stems (S1, S2) were determined by UPLC-MS/MS. A total of 15 cDNA libraries of the same tissue with three repetitions for each were constructed and sequenced. The BR-accumulation pattern and gene expression pattern were combined together for weighted gene co-expression network analysis (WGCNA). BR-accumulation-relative genes were then screened using two methods, based on the K.in value and BR biosynthetic pathway (ko00905), respectively. The result showed that photosynthesis-related genes and CYP450 family genes were actively involved and might play important roles in BR accumulation and/or its accumulation pattern. First and foremost, feedback inhibition was more likely to dominate the accumulation pattern of BR in the new shoots of tea plants. Moreover, three conserved miRNAs with their target transcriptional factors and target mRNAs had been figured out from negative correlation modules that might be strongly linked to the BR-accumulation pattern. Our study provided an experimental basis for the role of BR in tea plants. The excavation of genes related to the accumulation pattern of BR provided the possibility of cross-action studies on the regulation of BR biosynthesis and the study between BR and other hormones.