Tea (Camellia sinensis) is an important perennial horticultural crop, but the genetic control of leaf angle, a key trait affecting plant architecture and harvesting efficiency, remains unclear. In this study, we measured leaf angles at different leaf positions and examined the anatomy of the bending region between the leaf midrib and the main stem across 12 tea cultivars. Hongyan 1(HY 1) with large leaf angles and Hongyan 4(HY 4) with small leaf angles were selected for transcriptome analysis. Differentially expressed genes were mainly enriched in hormone signaling, MAPK signaling, and phenylpropanoid biosynthesis pathways. Two NAC transcription factors, CsNAC083 and CsVND1, were prioritized as candidates, and their expression patterns were examined by qRT-PCR. Sequence and phylogenetic analyses suggested that CsNAC083 is associated with inhibition of xylem differentiation, while CsVND1 is related to xylem formation and lignin deposition. Both proteins localized to the nucleus and showed direct interaction in yeast. Heterologous expression in tobacco showed that CsNAC083 overexpression was associated with increased leaf bending by reducing xylem differentiation and lignin deposition, whereas CsVND1 enhanced lignification and promoted leaf erectness. Co-expression of CsVND1 partially alleviated the phenotypes caused by CsNAC083 overexpression. These findings reveal a regulatory mechanism linking vascular development to leaf angle formation in tea plants and provide a potential genetic basis for optimizing plant architecture in tea cultivation.

Anthocyanins, a ubiquitous class of water-soluble phytochemicals renowned for their chromatic diversity and potent bioactivity, are integral to the phenotypic and metabolic plasticity of higher plants. Using an integrative multi-omics approach that combines transcriptomic and metabolomic profiling, we identified anthocyanin synthase (CsANS1) as the key genetic determinant responsible for interspecific variation in anthocyanin accumulation among tea plants. Architectural comparison of promoter regions revealed a 192-bp variation insertion in the CsANS1 cis-regulatory region with potential functional significance. This insertion was strictly conserved in anthocyanin-rich (purple-leaf) cultivars, including both natural and hybrid genotypes, but entirely missing in anthocyanin-deficient (green-leaf) cultivars. Dual-luciferase assays confirmed that this insertion enhances promoter activity. Additionally, we delineated a tripartite regulatory axis comprising CsmiR156b, CsSPL9, and CsMYB75 which orchestrates the spatiotemporal modulation of CsANS1 expression and, consequently, anthocyanin biosynthesis. Collectively, these findings provide a mechanistic paradigm for anthocyanin polymorphism in tea plants, implicating both cis-regulatory evolution and transcriptional network synergy as pivotal drivers of phytochemical diversification.

The tea plant stands as a globally cherished nonalcoholic beverage crop, but the genetic underpinnings of important agronomic and metabolomic traits remain largely unexplored. Here we de novo deep resequenced 802 tea plants and their relative accessions globally. By integrating public Camellia accessions, we constructed a comprehensive genome-wide genetic variation map and annotated deleterious mutations for 1,325 accessions. Population genetic analyses provided insights into genetic divergence from its relatives, different evolutionary bottlenecks, interspecific introgression and conservation of wild relatives. Our findings suggest the pivotal role of southwest China as the origin of tea plants, revealing the genetic diversity and domestication status of ancient tea plants. Genome-wide association studies herein identified thousands of substantial associations with leaf shape and metabolite traits, pinpointing candidate genes for crucial agronomic and flavor traits. This study illuminates the tea plant's evolution and provides references for tea plant design breeding.

Although tea (Camellia sinensis)/soybean (Glycine max) intercropping is widely applied in tea gardens, the underlying mechanisms driving tea quality promotion remain largely unclear. This study explores the effects of intercropping on tea quality, soil nutrient availability, and soybean growth and analyzes their mutual relationship. Field experiments revealed that intercropping increased tea leaf water extracts, polyphenols, and amino acids by 4.36–8.99%, 14.76–15.23%, and 14.73–16.36%, respectively, across two growth stages. Furthermore, intercropping boosted organic matter, available nitrogen (N), phosphorus (P), and potassium (K) in the tea rhizosphere. Enzyme activities, including acid phosphatase, alkaline phosphatase, urease, and β-glucosidase, were also elevated in tea/soybean intercropping. In soybean, shoot and root biomass, weight and number of nodules, and N, P, and K content increased over cultivation time. Correlation analysis showed that tea water extracts and polyphenols were positively linked to soil available P and alkaline phosphatase activities. Soybean root and nodule growth were correlated with soil N and P activation and tea water extracts, indicating that soybean-mediated underground interactions drive mineral nutrient mobilization in rhizosphere, further improving tea quality. This study provides mechanistic insights into tea/soybean intercropping, offering practical implications for sustainable tea cultivation practices.

Camellia ptilophylla, a precious tea variant, has an inferior flavor, possibly related to the specificity of its amino acid composition. In this study, significantly different compositions of amino acids were revealed through systematic analysis of C. ptilophylla and conventional tea, with low theanine but high levels of an unknown amino acid-like substance found in the above-ground parts of C. ptilophylla. Through isolation and structural analysis, the unknown substance was identified for the first time as 4-amino-5-hydroxyvaleric acid (named camptinine). Structural and content correlation analysis suggested that it might be a metabolic product diverted from glutamate, which is related to the decomposition of theanine. Function evaluation showed camptinine had anti-anxiety effect by increasing brain 5-hydroxytryptamine, similar to the positive control of theanine and estazolam, with milder organ impact in mice. This study offers novel insights into tea plant amino acid metabolism, and offers theoretical support for C. ptilophylla product development.

Purple teas are gaining popularity due to their significant health benefits. This study analyzed flavonoid metabolites in the second leaves of three purple tea varieties with stable purple shoots-'Hongfei' (HF), 'Danfei' (DF), and 'Ziya 24' (ZY24)-using UPLC-MS/MS, with 'Yinghong 9' (YH9), a green tea, as the control. The most abundant anthocyanins were cyanidin-3-O-glucoside, cyanidin-O-syringic acid, and pelargonidin-3-O-glucoside in HF, while ZY24 and DF accumulated additional delphinidin and petunidin derivatives. DF also contained malvidin-3-O-galactoside. Furthermore, 22 significantly enriched non-anthocyanin flavonoids were identified as potential co-pigments contributing to the vibrant leaf coloration. These findings reveal key anthocyanin and flavonoid profiles responsible for the distinct purple hues in the tender shoots of different purple tea varieties.

In tea (Camellia sinensis), anthocyanins are important secondary metabolites that are linked to leaf color. Anthocyanin biosynthesis is a complex biological process, in which multiple genes including structural and regulatory genes are involved. Here, we describe the cloning and characterizing of a new R2R3-MYB transcription factor gene, CsRAB, isolated from purple tea variety ‘Hongfei’. Consistent with its predicted role as a transcription factor, the CsRAB protein localized to nuclei when expressed in onion (Allium cepa) epidermal cell. A dual-luciferase reporter assay demonstrated that CsRAB acts as a transcriptional activator in vivo. CsRAB overexpression in Arabidopsis seedlings led to higher expression levels of anthocyanin biosynthesis-related genes, and consequently, purple stems and higher anthocyanin contents were exhibited in overexpressing lines compared to wild type. The results indicated that CsRAB plays critical roles in positively regulating anthocyanins biosynthesis in tea plants.

The fresh leaves of Kucha No.6 with high theacrine as raw materials in different seasons were processed into green tea, white tea and black tea. The tea suitability of Kucha No.6 was comprehensively analyzed by sensory evaluation and main quality components. The sensory evaluation results showed that three types of Kucha No.6 tea all had different degrees of bitterness (green tea > white tea > black tea ). Among of them, green tea had a floral and bean fragrance, a mellow and bitter taste. White tea had a medical and floral fragrance, a mellow taste, and black tea had sweet and rich fragrance, mellow and refresh taste. Additionally, the results of main quality components analysis showed that the contents of some components related to bitterness, such as tea polyphenols, total catechins, EGCG, and EGC, were significantly higher in green and white tea than those in black tea. Furthermore, the contents of theacrine in three types of Kucha No.6 tea in spring were significantly higher than those in other two seasons. According to this study, Kucha No.6 containing high theacrine was more suitable for making black tea, not only because the high contents of theacrine, but also of the characteristics of sweet and rich fragrance, mellow and refresh taste. Although green tea and white tea made by Kucha No.6 had strong bitter taste, they were more suitable for promoting as further processed products because of their high contents of healthcare functional ingredients such as theacrine, EGCG, etc. This study provides more theoretical and practical basis for the further development and utilization of Kucha resources.

Fenghuang Dancong tea (FHDC), a famous oolong tea originating from Guangdong Province in China, is known for its rich and unique fragrance. Nevertheless, the identification of the key aroma compounds with the difference fragrance types of FHDC remains uncertain. In order to characteristic the volatile components in different fragrance types of FHDC, 10 well-known fragrance types of FHDC and Tieguanyin (TGY) as a control were analyzed by headspace solid-phase microextraction (HS-SPME) coupled with gas chromatography mass spectrometry (GC-MS). Results indicated that 172 volatile compounds were identified as common volatile compounds among all the tea samples. A total of 16 compounds were identified as key compounds that could be used to distinguish between FHDC and TGY. Among the 10 FHDC fragrance types, indole, hotrienol, benzyl nitrile, and jasmine lactone were found to be the most abundant compounds. Despite the presence of certain similarities in aroma components, each type exhibits unique fragrance characteristics as a result of variation in compound composition content and proportion. Furthermore, using statistical and odor activity value analysis, 20 aroma-active compounds were recognized as potential characteristic markers accountable for the diverse fragrance types of FHDC. This research enhances our comprehension of the various fragrance types of FHDC and provides reference values for their rapid identification in the market.

Guangdong black teas have diverse flavors and aromas. To explore the molecular basis of these aromas, we extracted and analyzed the volatile flavor compounds of 31 black tea samples from 7 districts (Yingde, Luokeng, Renhua, Meizhou, Chaozhou, Lianshan, and Heyuan) in Guangdong Province with headspace solid-phase microextraction (HS-SPME) coupled with gas chromatography–mass spectrometry (GC–MS). Then, 135 volatile flavor compounds (VFCs) were identified and grouped into 12 classes according to their chemical structure. Notably, alcohols accounted for 31.40–44.43% of total VFCs. The score plot of supervised partial least squares-discriminant analysis (PLS-DA) revealed good discrimination for most black tea samples. Additionally, 64 compounds with variable importance in projection > 1.0 were identified as differential odorants. Through an odor activity value analysis, eight volatile compounds were identified as the key active differential VFCs: linalool, methyl salicylate, phenylethyl alcohol, p-cresol, 3-methyl-butanoic acid, geraniol, benzaldehyde, and benzeneacetaldehyde. Thus, benzeneacetaldehyde and linalool in YJ-Yingde samples, benzaldehyde in Luokeng samples with an almond-like aroma, phenylethyl alcohol in the Heyuan samples, and p-cresol and 3-methyl-butanoic acid in the Chaozhou samples were the key volatile flavor compounds that could differentiate local black teas from other black teas. These findings will enrich the research in tea aroma chemistry and provide a method for identifying the origins of Guangdong black teas.

Tea is one of the world’s oldest crops and is cultivated to produce beverages with various flavours. Despite advances in sequencing technologies, the genetic mechanisms underlying key agronomic traits of tea remain unclear. In this study, we present a high-quality pangenome of 22 elite cultivars, representing broad genetic diversity in the species. Our analysis reveals that a recent long terminal repeat burst contributed nearly 20% of gene copies, introducing functional genetic variants that affect phenotypes such as leaf colour. Our graphical pangenome improves the efficiency of genome-wide association studies and allows the identification of key genes controlling bud flush timing. We also identified strong correlations between allelic variants and flavour-related chemistries. These findings deepen our understanding of the genetic basis of tea quality and provide valuable genomic resources to facilitate its genomics-assisted breeding.

Three purple tea varieties (lines), namely Hongye-1, Hongye-2, Danfei in different seasons as test materials, were made into green tea, white tea and black tea. And we assessed the suitability of purple tea varieties (lines) by tea quality analysis and sensory evaluation. The results showed that the contents of physical and chemical contents were higher in green teas and white teas than in black teas. The green teas had the highest physical and chemical contents, which had the average content of 4.24% to 4.69% in soluble sugar in three seasons; while the black teas were 3.54% to 3.96%. Amino acid contents in white teas were higher than in green teas and black teas, which was above 3.40% in white tea; while in black tea and green tea amino acid contents were about 3%. Green teas made with purple tea had the highest content of anthocyanins in summer, second in autumn and lowest in spring. Anthocyanin contents in green teas were 0.086% to 0.115% in summer. In addition to the trace anthocyanins detected in spring white tea, neither white tea nor black tea were detected with anthocyanins in different seasons. Sensory evaluation showed that the white teas made from the purple tea were rich in elegant floral or fruit aroma, with sweet and mellow tastes; the black tea had the characteristics of rich sweetness aroma, sweet and fresh taste; and the green tea retained more quality components, and had reddish violet soup color. Therefore, purple tea is more suitable to be made into black tea and white tea; and green tea can be popularized as a new special tea drink. This study provides a theoretical and practical basis for the further use of purple tea.

In order to study the composition of volatile aroma components in Fuliang black tea and screen the key aroma components, in this study, headspace-solid phase microextraction-gas chromatography-mass spectrometry (HS-SPME-GC-MS) was performed to identify the volatile components of Fuliang black tea, and the key aroma components were selected by the odor activity value (OAV) and principal component analysis (PCA). The 73 kinds of volatile components were isolated and identified in Fuliang black tea, including 16 alcohols, 12 esters, 11 hydrocarbons, 10 ketones, 9 aldehydes, 6 acids, 6 heterocycles and 3 phenols and their derivatives. The kinds and relative contents of alcohols were the highest, among which 44 kinds of volatile components had no significant difference among the three Fuliang black tea samples, and 29 kinds had significant difference (P<0.05). The OAV of 15 volatile components was not less than 1. Finally, 11 compounds were selected as the key aroma components of Fuliang black tea, including citral, benzyl alcohol, geraniol, α-lonone, trans-nerolidol, geranylacetone, phenylethanol, methyl salicylate, hexanal, linalool and 2-methylpyrazine. The results of this study provided a theoretical basis for analyzing the characteristic flavor quality of Fuliang black tea, clarifying its aroma precursors and quality oriented control.

Volatile flavor compounds in 112 black teas from seven countries were analyzed by untargeted metabolomics using headspace solid-phase microextraction and gas chromatography-mass spectrometry (HS-SPME/GC-MS). Multivariate statistical analysis and odor activity values (OAVs) were used to classify these samples and identify key odorants. A total of 140 volatile flavor compounds (VFCs), including 12 different groups, were identified, and alcohols were prevalent in China and India samples, accounting for 40.83% and 34.96% of the total VFCs, respectively. Eight volatile compounds with OAVs > 1 were identified as key active differential odorants in Chinese, Indian, and Sri Lankan samples, including linalool, pentanoic acid, methyl salicylate, hexanoic acid, 1-methyl-naphthalene, phenylethyl alcohol, geraniol, and β-ionone. Linalool, pentanoic acid, and hexanoic acid in Indian black teas, phenylethyl alcohol in Chinese black teas, and 1-methyl-naphthalene, β-ionone in Sri Lankan black teas could be used to discriminate different black tea groups. A total of 12-14 VFCs with OAVs > 1 were identified as key active aromatics in Chinese black tea sample. Linalool and benzeneacetaldehyde in Yingde (Guangdong) black tea, methyl salicylate in Taiwanese samples, and benzeneacetic acid in Anhui black tea could be used as biomarkers to distinguish them from other Chinese samples. Sensory evaluation results showed that most black teas presented the common sweet, floral odors, which were consistent with GC-MS analysis. These results will contribute to characterize the odor metabolome of black teas and provide biochemical basis for identifying the authenticity of different black teas. PRACTICAL APPLICATION: Linalool, pentanoic acid, and hexanoic acid in Indian black teas, phenylethyl alcohol in Chinese black teas, 1-methyl-naphthalene, β-ionone, and methyl salicylate in Sri Lankan black teas could be used to discriminate black teas from the three countries. Linalool and benzeneacetaldehyde in Yingde black teas, methyl salicylate in Taiwanese black teas, and benzeneacetic acid in Anhui black tea are the potential biomarkers to distinguish these teas from other Chinese black teas.

The characteristic secondary metabolites in tea (theanine, caffeine, and catechins) are important factors contributing to unique tea flavors. However, there has been relatively little research on molecular markers related to these metabolites. Thus, we conducted a genome-wide association analysis of the levels of these tea flavor-related metabolites in three seasons. The theanine, caffeine, and catechin levels in Population 1 comprising 191 tea plant germplasms were examined, which revealed that their heritability exceeded 0.5 in the analyzed seasons, with the following rank order (highest to lowest heritabilities): (+)-catechin > (−)-gallocatechin gallate > caffeine = (−)-epicatechin > (−)-epigallocatechin-3-gallate > theanine > (−)-epigallocatechin > (−)-epicatechin-3-gallate > catechin gallate > (+)-gallocatechin. The SNPs detected by amplified-fragment SNP and methylation sequencing divided Population 1 into three groups and seven subgroups. An association analysis yielded 307 SNP markers related to theanine, caffeine, and catechins that were common to all three seasons. Some of the markers were pleiotropic. The functional annotation of 180 key genes at the SNP loci revealed that FLS, UGT, MYB, and WD40 domain-containing proteins, as well as ATP-binding cassette transporters, may be important for catechin synthesis. KEGG and GO analyses indicated that these genes are associated with metabolic pathways and secondary metabolite biosynthesis. Moreover, in Population 2 (98 tea plant germplasm resources), 30 candidate SNPs were verified, including 17 SNPs that were significantly or extremely significantly associated with specific metabolite levels. These results will provide a foundation for future research on important flavor-related metabolites and may help accelerate the breeding of new tea varieties.

“Yinghong 9” is a widely cultivated large-leaf variety in South China, and the black tea made from it has a high aroma and strong sweet flavor. “Huangyu” is a light-sensitive tea variety with yellow leaves. It was cultivated from the bud-mutation of “Yinghong 9” and has a very low level of chlorophyll during young shoot development. Due to chlorophyll being involved in carbon fixation and assimilation, the changes in photosynthesis might potentially affect the accumulation of flavor metabolites, as well as the quality of “Huangyu” tea. Although “Huangyu” has a golden yellow color and high amino acid content, the mechanism underlying the formation of leaf color and drinking value remains unclear. The widely targeted metabolomics and GC-MS analysis were performed to reveal the differences of key metabolites in fresh and fermented leaves between “Yinghong 9” and “Huangyu.” The results showed that tea polyphenols, total chlorophyll, and carotenoids were more abundant in “Yinghong 9.” Targeted metabolomics analysis indicated that kaempferol-3-glycoside was more abundant in “Yinghong 9,” while “Huangyu” had a higher ratio of kaempferol-3-glucoside to kaempferol-3-galactoside. Compared with “Yinghong 9” fresh leaves, the contents of zeaxanthin and zeaxanthin palmitate were significantly higher in “Huangyu.” The contents of α-farnesene, β-cyclocitral, nerolidol, and trans-geranylacetone, which were from carotenoid degradation and involved in flowery-fruity-like flavor in “Huangyu” fermented leaves, were higher than those of “Yinghong 9.” Our results indicated that “Huangyu” was suitable for manufacturing non-fermented tea because of its yellow leaf and flowery-fruity-like compounds from carotenoid degradation.

Aroma is one of the key sensory attributes of tea. Quantitative volatile measurement is essential but technically challenging. Sample extraction is the first critical step for quantification. However, volatile extraction method has not been systematically optimized. The goal of this research was to establish a quantitative volatile measurement method in tea. For this end, solvent-assisted flavour evaporation method was used; the effects of the numbers of extraction, stirring, sample amounts, solid-liquid ratios and postharvest treatments on volatile isolation were compared. We demonstrated that stirring did not improve total volatile recovery; the number of volatiles detected was positively correlated with sample amounts and the solid-liquid ratio, excess sample amounts compromised the quantification accuracy of abundant volatiles; cryopreservation largely preserved the volatile contents and composition of fresh tea leaves. Based on these findings, volatile extraction method was optimized. The volatile compounds were qualitatively and quantitatively analysed by GC-MS and GC-FID, respectively; the FID relative response factor for individual volatile was calculated to calibrate individual peak area of tea volatile. By integrating these techniques, a quantitative volatile measurement method was established. As a proof of concept, the described method was applied to investigate the seasonal effects on fresh tea leaf volatile. The described method should also be applicable to other horticultural crop species.

我国华南地区分布较多古茶树及地方特异茶树种质,这些种质不仅是生物学研究的宝贵材料,同时也是优异茶树品种选育的基础.茶树种质异地保存可根据果实、枝条生长的具体情况,采用不同的方式进行保存,主要包括茶籽播种,穗条嫁接和扦插繁育技术,本文通过对这三种技术要点进行总结,有助于茶树种质资源的收集、保存及推广应用.

Characteristic aroma is a well-appreciated feature contributing to tea quality. Although extensive studies have been made to investigate aroma biosynthesis and gene expressions during tea making processes, it remains unclear whether the endogenous volatile biosynthesis during postharvest tea processing contributes to the aroma quality of made tea. To critically evaluate this question, we used the same batch of fresh tea leaves and produced three different types of tea with different degrees of fermentation (green tea, oolong tea, and black tea). Total volatiles were extracted by solvent-assisted-flavor evaporation, then quantified by gas chromatography-flame ionization detector combined with response factor correction for quantitative measurement. Compared with fresh tea leaves, the volatile profiles of the made teas were dramatically altered, with significant loss for the majority of endogenous volatiles and simultaneous gain for non-endogenous volatiles. By calculation of odor-activity values, the potential volatiles contributing to the aroma characteristics of each tea type were identified. Our data suggest that postharvest synthesis of endogenous volatiles did not contribute to the aroma quality of made tea.

为了探究宁红茶香气感官特征、挥发性化合物组成及其分子感官基础,采用定量描述分析(quantitative description analysis,QDA)与顶空固相微萃取-气质联用(headspace-solid phase microextraction-gas chromatography-mass spectrometry,HS-SPME-GC-MS)相结合,对8份典型宁红茶的香气特征及挥发性化合物进行分析,之后利用偏最小二乘法(partial least squares regression,PLSR)筛选对其香气特征具有重要贡献的挥发性成分.结果表明,宁红茶香气可由筛选出的8个香气术语及其定义进行表征,其香气特征以果香为主,甜香和花香为辅,其中花香和甜香相关性大,焙烤香和果香相关性大,辛香与清香相关性大.鉴定出74个共有挥发性成分,以醇类含量最高,酯类、酸类、醛类、酮类次之,各宁红样品之间的挥发性成分含量差异性较大.最终筛选出16个对宁红茶香气特征具有重要贡献的化合物,分别为香叶醇、反式-橙花叔醇、苯乙醇、苯甲醛、芳樟醇、α-紫罗酮、β-水芹烯、罗勒烯、β-紫罗酮、橙花醇、棕榈酸乙酯、3-糠醛、苯甲醇、己酸、反式-3-己烯酸和水杨酸甲酯.实验结果为进一步研究宁红茶香气物质前体、生化过程和品质定向调控提供了基础.