As a significant economic crop in China, the flavor quality of tea plays a crucial role in determining its economic value and serves as a key factor in the competitive advantage of the high-quality development of the tea industry. Tea plants inoculated with the endophyte Luteibacter sp. CsE7 can significantly improve their nitrogen fixation, flavor and quality of tea products, leading to increased utilization efficiency and economic value of summer-autumn tea products. This study examined the effects of endophyte CsE7 on the total nitrogen content, growth status, and quality-related compounds of tea plants. The nitrogen fixation and plant-growth-promoting (PGP) activities of CsE7 were assessed to determine its effectiveness as a bacterium that supports nitrogen fixation and enhances plant growth. Through genomic and transcriptomic analyses of CsE7, two key nitrogenase proteins, CsENifB1 and CsENifB2, were identified as primary contributors to its nitrogen-fixation capability. The investigation of PGP traits revealed that CsE7 enhances plant growth by producing phytohormones, aiding siderophore biosynthesis, and synthesizing 1-aminocyclopropane-1-carboxylate (ACC) deaminase. Based on the evaluation results of tea shoots treated with CsE7 through irrigation inoculation, it was observed that CsE7 significantly increased the weight of hundred-bud samples, and enhanced axillary bud development, and stem elongation. Inoculation with CsE7 enhanced free amino acids and theanine levels in tea shoots, enriching the taste profile while maintaining the polyphenol-to-amino acid ratio. In conclusion, Luteibacter sp. CsE7 demonstrated notable nitrogen fixation and growth-promoting capabilities, thereby enhancing the quality of tea shoots. These findings highlight its potential significance for the summer-autumn tea industry and offer a novel perspective for enhancing tea flavor quality.

Cold tolerance and tea quality are essential for profitable tea cultivation, yet the genetic interplay between them remains elusive. Here, we systematically evaluated cold tolerance and quantified 12 key tea quality-related metabolites over two consecutive years of 108 geographically diverse tea accessions in China. Multi-trait genome-wide association mapping identified a central hub regulator, COLD AND CATECHINS REGULATOR 1 (CCR1), significantly associated with cold tolerance and catechins biosynthesis in tea plants. Functional analysis demonstrated that CsCCR1 positively regulates cold tolerance and catechins accumulation in tea plants, and that a missense variation (A-to-C) in CsCCR1 significantly enhances cold tolerance and catechins accumulation. Exogenous application of catechins (EGCG/EGC/EC) could also significantly alleviate cold-induced oxidative damage through ROS scavenging. We demonstrated that CsCCR1, activated by upstream regulators CsLUX and CsKUA1, directly activates catechin biosynthetic genes (CsCHS1, CsFLS1, CsSCPL4, CsSCPL5) and a novel cold-responsive gene CsELIP1. Furthermore, CsCCR1 physically interacts with CsCBF1/3 to form a transcriptional activation complex that synergistically amplifies expression of these downstream targets, thereby simultaneously modulating cold tolerance and catechins biosynthesis. Our findings underscore the importance of CsCCR1 in linking cold tolerance with quality formation of tea plants, offering targets for breeding elite tea cultivars with superior cold resistance and quality.

Tea quality is highly affected by seasonal changes which involve a complex interplay of environmental factors. Understanding how the seasonal factors affect metabolic pathways of altered-ploidy genotypes can provide insights into optimizing cultivation and processing practices to ensure consistent and high-quality tea production. In this study, we investigated the response of three genotypes of tea in four seasons (May, June, July, August). We used the HPLC and RNAseq approaches with InterPro and STRING tools for construction of DEGs-networks to reveal protein interactions. The results showed, that the seasonal factor more strongly affected catechins, caffeine and L-theanine levels than the genotype factor. Strong enrichment of phenylpropanoid pathway and stress responsive pathways was observed in August as compared to May. Among three genotypes, triploid #619 was less affected by season as compared to both aneuploid #582 and diploid cv. Kolkhida. According to GO and KEGG, the greater enrichment of the signalling pathways, amino acid and flavonol biosynthesis were observed in #619 and #582 as compared to cv. Kolkhida which showed greater enrichment of the abiotic stress response pathway. Future research should focus on validating these findings through functional studies and exploring the broader ecological implications of these adaptive responses in tea cultivation systems.

Withering is a crucial step in white tea processing that significantly impacts the final product quality. Traditional solar withering, despite its effectiveness, suffers from inconsistency due to variable weather and spectral composition, resulting in unstable quality. Although artificial light sources have emerged as a controllable alternative for white tea withering, the role of spectral characteristics in quality formation during withering remains unclear. To address this gap, the present study investigated the effects of light quality on the withering of Sangzhi white tea (SWT). The results showed that RL (red light) significantly promoted the accumulation of theanine, reaching 27.6 mg/g, and reduced the ratio of tea polyphenols to amino acids, thereby enhancing the sweet and mellow taste of the tea. In contrast, far-red light (FRL) uniquely increased the contents of benzaldehyde (59.9 +/- 2.5 mu g/g), geraniol (51.4 +/- 11.3 mu g/g), and trans-beta-ionone (3.6 +/- 0.6 mu g/g), intensifying floral and fruity aromas. Yellow light (YL) improved soluble sugar content and texture, while blue light (BL) exerted intermediate effects. Multivariate analyses (PCA and PLS-DA) further confirmed that light quality is a critical determinant of flavor composition, as evidenced by the distinct clustering patterns of metabolic profiles. Notably, RL and FRL treatments significantly promoted the quality formation of SWT, as evidenced by enhanced flavor compounds and desirable sensory characteristics. These findings not only elucidate the photoregulatory mechanisms underlying tea quality formation but also establish a novel framework for precision processing. By integrating spectral optimization with metabolic insights, this work provides actionable strategies to stabilize and enhance the sensory attributes of SWT. This addresses academic and industrial demands for standardized, high-quality production.

Abstract The albino leaves of cold-sensitive tea plants exhibited a marked reduction in chlorophyll content. However, the underlying regulatory mechanism remains elusive. In this study, we determined lower chlorophyll levels in tender leaves of cold-sensitive ‘Baiye 1’ compared to green leaves during the spring. Comparative transcriptome analyses identified the chlorophyll biosynthesis gene CsPORA, which was significantly downregulated in albino leaves. Functional assays confirmed that CsPORA positively regulates chlorophyll content. Electrophoretic mobility shift assay, yeast one-hybrid, dual-luciferase, and GUS staining results demonstrated that CsNAC87 binds to the promoter of CsPORA and suppresses its expression. Additionally, CsZAT12 physically interacts with CsNAC87 to enhance the repression. Overexpression of either CsZAT12 or CsNAC87 negatively regulated chlorophyll accumulation in tea plants and tobacco leaves, while co-transformation of CsZAT12 and CsNAC87 intensified the albino phenotype in tobacco leaves. Low temperature treatment of ‘Baiye 1’ triggered the marked upregulation of CsNAC87 and CsZAT12, leading to dramatical downregulation of CsPORA and leaf albinism. Collectively, our study reveals a novel cold-responsive CsZAT12-CsNAC87 module that negatively regulates chlorophyll synthesis by repressing CsPORA, providing new insights into chlorophyll metabolism in albino leaves of cold-sensitive tea cultivars.

Fluoride (F) is a nonessential but potentially harmful element for plants, especially when present in excess. The tea plant is known for its ability to hyperaccumulate F from the soil and eventually accumulates in the leaves; however, how the tea plant transports F to the leaves remains unclear. Here, we found that Se can significantly decrease the transport efficiency of F from root to leaf. Therefore, RNA-Sequencing was performed on tea roots cotreated with selenite and fluoride, and then we isolated a plasma membrane-localized F transporter CsNPF2.3 from tea plant roots and examined its role in transport of F in tea plants. The results showed that CsNPF2.3 exhibited F transport activity when heterologously expressed in yeast. Expression pattern analysis revealed that CsNPF2.3 is expressed in epidermal cells, cortex cells, and xylem parenchyma cells in roots. Overexpression of CsNPF2.3 in tea roots significantly increased F content in the root, stem, and leaf, and enhanced the transport efficiency of F from root to leaf. Furthermore, in nine tea cultivars, CsNPF2.3 expression in the root was significantly positively correlated with F content in the leaf and root, and the transport efficiency of F from root to leaf. Altogether, these findings suggest that CsNPF2.3 was involved in uptake and transport of F in tea plants.

Theanine, a tea plant (Camellia sinensis)-specific non-proteinogenic amino acid, is one of the most important components conferring the taste quality and health benefits of tea. It is primarily synthesized in roots of tea plants and transported to new shoots, where it is mainly distributed to the young stem; however, tea is predominantly produced from young leaves. To promote more theanine allocation to young leaves, the molecular mechanism underlying theanine distribution between stems and leaves requires elucidation. In this study, we found the ratios of stem-to-leaf theanine content in the new shoots of 11 tea plant cultivars ranged from 3.8 to 8.8. Analyses on transcriptome and gene expression demonstrated that the expression of CATIONIC AMINO ACID TRANSPORTER1 (CsCAT1), an amino acid transporter-encoding gene, was highly correlated with the ratios of theanine content in the stem and leaf (r = 0.97, P < 0.0001). Further analyses indicated that CsCAT1 localizes in the plasma membrane and has theanine transport activity. Moreover, CsCAT1 was predominantly expressed in the vascular ray cells in the stem. Finally, we found that repression of CsCAT1 increased theanine content in young leaves and the ratio of leaf-to-stem theanine content. These results indicate that CsCAT1 modulates theanine distribution between stem and leaf and provides a target for increasing theanine content in young leaves of tea plants.

Currently, the field of tea plant biology is rapidly advancing, with numerous significant scientific inquiries being raised and investigated. Meanwhile, a substantial number of functional genes have been reported. However, due to the lack of certain in vivo validation techniques, much of the expression information for these functional genes is at the tissue level in tea plants and remains unclear at the cell-type level. In this study, an in situ PCR method for detecting gene expression heterogeneity in tea plant root cells is presented. A detailed description of the procedure and precautions involved in this method is provided and suggestions offered for addressing potential experimental challenges. Finally, the expression patterns of CsGL3, CsCAT2, and CsAAP4 in tea plant root cells were taken as examples. The present results showed that CsGL3 was predominantly expressed in root epidermal cells, while CsCAT2 shows strong expression in pericycle and cortex. The expression of CsAAP4 was not detected in root cells. These findings are consistent with previous reports, indicating that this method is feasible for the detection of gene expression patterns in tea plant root cells.

Tea plant (Camellia sinensis) accumulates abundant secondary metabolites under cold stress, some of which are thought to play important roles in enhancing cold tolerance. To explore novel secondary metabolites involved in cold tolerance, we conducted an untargeted metabolomics analysis of tea plants under cold stress treatment. This revealed a novel acylated flavonoid, kaempferol-3-O-(6″-p-coumaroyl)-glucoside (KCG), in which accumulation positively correlated with stress severity. The compound was purified and structurally characterized using nuclear magnetic resonance (NMR) spectroscopy. Exogenous application of this flavonoid significantly improved cold tolerance in tea plants, indicating its role as a defensive metabolite. Transcriptome sequencing identified candidate acyltransferases, with tea hydroxycinnamoyl transferase (CsHCT) emerging as a key biosynthetic gene. In vitro assays confirmed that recombinant CsHCT catalyzes the formation of KCG from kaempferol-3-O-glucoside and p-coumaroyl-CoA. Overexpression of CsHCT in tea seedlings and Arabidopsis thaliana resulted in markedly elevated levels of this flavonoid and cold resistance of these plants, validating its in vivo role. Our findings elucidate the biosynthesis of acylated flavonoids in tea plants and highlight CsHCT as a genetic target for enhancing cold resistance. This study provides foundational insights for advancing cold-resistant tea breeding programs.

Gray blight is a serious foliar disease that significantly threatens tea plant cultivation. Although dynamic histone methylation was reported in regulating plant immunity, the specific roles of this epigenetic modification in tea plant disease resistance have yet to be fully elucidated. This study demonstrates that the protein arginine methyltransferase CsPRMT5, which catalyzes the symmetric dimethylation of histone H4R3 (H4R3sme2), is involved in the tea plant response to gray blight. Transcription of CsPRMT5 and the level of histone H4R3 methylation in tea were downregulated following infection by the fungal pathogen Pseudopestalotiopsis (Ps). A negative correlation was observed between the resistance of tea plants to Ps and the expression level of CsPRMT5 across various cultivars. Downregulation of CsPRMT5 expression led to reduced H4R3sme2 levels, elevated expression of defense-related genes, and lower reactive oxygen species (ROS) production after Ps infection, thus enhancing pathogen resistance of tea. Furthermore, complementation of Atprmt5 mutant with CsPRMT5 restored the susceptibility to Ps infection in Arabidopsis. Chromatin Immunoprecipitation Sequencing (ChIP-seq)and Chromatin Immunoprecipitation quantitative PCR (ChIP-qPCR) analyses revealed that CsPRMT5 binds to defense-related genes, including CsMAPK3, and regulates their expression through H4R3sme2 modification. Collectively, the results indicate that CsPRMT5 negatively regulates the immune response to pathogens through repressing CsMAPK3 expression in tea plants.

High temperatures significantly affect tea yield and quality. Arginine methylation is crucial for plant growth and environmental adaptation. However, its role in regulating plant responses to high temperatures remains unclear. In this study, we identified an important Type II arginine methyltransferase, PRMT5, in tea plants and confirmed its methyltransferase activity both in vivo and in vitro. Our findings revealed that CsPRMT5-mediated symmetric dimethylation of histone H4R3 (H4R3sme2) was markedly reduced under high-temperature conditions in tea plants. Both the inhibitor and gene-silencing approaches led to decreased levels of H4R3sme2 modification, resulting in alterations in theanine and catechins. We employed a genome-wide approach to analyze the RNA sequencing (RNA-seq) of tea plants subjected to ambient high temperatures, PRMT5 inhibitors, and PRMT5 silencing, along with H4R3sme2 and CsPRMT5 chromatin immunoprecipitation sequencing (ChIP-seq). Comparative analysis of these datasets indicated that genes regulated by H4R3sme2 were predominantly enriched within the reactive oxygen species (ROS), calcium ion, and hormone signalling pathways under elevated temperature conditions. Furthermore, we validated CsCDPK9 as a target gene regulated by H4R3sme2 and found that silencing CsCDPK9 resulted in increased theanine content and decreased catechin content at high temperatures. Our findings suggest that CsPRMT5-mediated H4R3sme2 plays a pivotal role in the growth of tea plants, as well as in their adaptability to fluctuations in ambient temperatures. This study provides new insights into breeding strategies aimed at developing crops that are better equipped to withstand environmental changes induced by climate change.

Theanine is a core secondary metabolite responsible for the sensory qualities and health benefits of tea. Theanine levels are high in new tea plant (Camellia sinensis) shoots that arise during early spring, but then significantly decrease in late spring, causing a rapid decline in the quality of green tea processed from the late-spring harvest. However, the molecular mechanisms underlying this seasonal decrease in theanine levels remain unknown. In a previous genetic screen, we identified the YFR045W yeast mutant that displayed a hypersensitivity to theanine feeding due to enhanced theanine accumulation. YFR045W encodes a putative mitochondrial carrier and was designated Theanine Hypersensitive 1 (THS1). Expression of CsTHS1, the functional homolog of THS1 in tea plants, rescued this yeast mutant phenotype. Importantly, CsTHS1 expression is induced in late-spring new shoots, and CsTHS1 exhibits a high affinity for theanine. Yeast mitochondria expressing CsTHS1 demonstrate increased theanine transport activity, and recombinant CsTHS1 proteo-liposomes can also transport theanine. Additionally, CsTHS1 overexpression or repression in new tea shoots significantly decreased or increased theanine accumulation, respectively. Our findings establish a relationship between CsTHS1-mediated theanine transport into mitochondria and the observed reduction in theanine accumulation in the late-spring new tea shoots. Our study supports a mechanism whereby CsTHS1 mediates theanine entry into mitochondria for degradation by the mitochondria-localized γ-glutamyl transpeptidase (CsGGT2).

Detection of extracellular DNA (exDNA) released by invasive pathogens is crucial for understanding biotic stress in plants but remains challenging due to the lack of practical sensing tools. This study introduces a fluorescent nanosensor for remote, noninvasive detection of exDNA in plant tissues. Comprising GelGreen and polyethylenimine-modified silica nanoparticles, the nanosensor forms a self-reporting nanoplatform that simultaneously captures exDNA and generates signals. DNA-induced cross-linking causes nanosensor aggregation, producing detectable fluorescence measurable by confocal microscopy and flow cytometry with sensitivity at ng mL-1 levels. After injection, the nanosensors reside in the apoplastic space, capturing exDNA over extended periods and providing stable fluorescence signals. The study also demonstrates that invasive bacteria trigger nanosensor aggregation in plant leaves via bacterial surface DNA, rapidly activating the nanosensors. This underscores the role of exDNA in pathogen infections and highlights the potential of this nanosensor for advancing plant nanotechnology and pathophysiological research.

Plant secondary metabolites are critical quality-conferring compositions of plant-derived beverages, medicines, and industrial materials. The accumulations of secondary metabolites are highly variable among seasons; however, the underlying regulatory mechanism remains unclear, especially in epigenetic regulation. Here, we used tea plants to explore an important epigenetic mark DNA methylation (5mC)-mediated regulation of plant secondary metabolism in different seasons. Multiple omics analyses were performed on spring and summer new shoots. The results showed that flavonoids and theanine metabolism dominated in the metabolic response to seasons in the new shoots. In summer new shoots, the genes encoding DNA methyltransferases and demethylases were up-regulated, and the global CG and CHG methylation reduced and CHH methylation increased. 5mC methylation in promoter and gene body regions influenced the seasonal response of gene expression; the amplitude of 5mC methylation was highly correlated with that of gene transcriptions. These differentially methylated genes included those encoding enzymes and transcription factors which play important roles in flavonoid and theanine metabolic pathways. The regulatory role of 5mC methylation was further verified by applying a DNA methylation inhibitor. These findings highlight that dynamic DNA methylation plays an important role in seasonal-dependent secondary metabolism and provide new insights for improving tea quality.

Cold stress declines the quality and yield of tea, yet the molecular basis underlying cold tolerance of tea plants (Camellia sinensis) remains largely unknown. Here, we identified a circadian rhythm component LUX ARRHYTHMO (LUX) that potentially regulates cold tolerance of tea plants through a genome-wide association study and transcriptomic analysis. The expression of CsLUX phased with sunrise and sunset and was strongly induced by cold stress. Genetic assays indicated that CsLUX is a positive regulator of freezing tolerance in tea plants. CsLUX was directly activated by CsCBF1 and repressed the expression level of CsLOX2, which regulates the cold tolerance of tea plants through dynamically modulating jasmonic acid content. Furthermore, we showed that the CsLUX-CsJAZ1 complex attenuated the physical interaction of CsJAZ1 with CsICE1, liberating CsICE1 with transcriptional activities to withstand cold stress. Notably, a single-nucleotide variation of C-to-A in the coding region of CsLUX was functionally validated as the potential elite haplotype for cold response, which provided valuable molecular markers for future cold resistance breeding in tea plants.

Theanine metabolism is a necessary biological process during the planting and production of tea that determines tea quality. There is currently little knowledge about the transcriptional regulation of theanine metabolism in tea plants. In this study, we demonstrated that γ-glutamyl-transpeptidase CsGGT4, as a homologous protein of the theanine hydrolase CsGGT2, exhibited a higher theanine synthesis catalytic efficiency. Homology modeling and molecular docking showed that differential protein structures between CsGGT2 and CsGGT4 implied their different biological functions in tea plants. Theanine content correlated significantly with the expression of CsGGT2, CsGGT4 and the transcription factor CsMYB73 in tea shoots from different seasons. Additionally, CsMYB73 was confirmed to act as a nucleus-localized transcription factor (TF), directly interacts with the CsGGT2 and CsGGT4 promoters, serving as an activator of CsGGT2 and a suppressor of CsGGT4. Consequently, this leads to a negative association with theanine accumulation in tea shoots. Furthermore, the continuous increase in CsMYB73 produced a significantly increase in CsGGT2 expression and inhibited CsGGT4 expression. The present study reveals that the degradation of theanine has been observed to increase, concomitantly with the inhibition of theanine synthesis, resulting in a significant decline in the accumulation of theanine in tea shoots during the process of seasonal greening in ‘Huangkui’ leaves. This study contributes to the broader comprehension of the intricate transcriptional regulatory hierarchy that governs the metabolism of theanine in tea shoots, offering novel approaches for managing tea plantations and enhancing tea quality.

Root-synthesized secondary metabolites are critical quality-conferring compounds of foods, plant-derived medicines, and beverages. However, information at a single-cell level on root-specific secondary metabolism remains largely unexplored. L-theanine, an important quality component of tea, is primarily synthesized in roots, from which it is then transported to new shoots of tea plant. In this study, we present a single-cell RNA sequencing (scRNA-seq)-derived map for the tea plant root, which enabled cell-type-specific analysis of glutamate and ethylamine (two precursors of theanine biosynthesis) metabolism, and theanine biosynthesis, storage, and transport. Our findings support a model in which the theanine biosynthesis pathway occurs via multicellular compartmentation and does not require high co-expression levels of transcription factors and their target genes within the same cell cluster. This study provides novel insights into theanine metabolism and regulation, at the single-cell level, and offers an example for studying root-specific secondary metabolism in other plant systems.

Ethylamine (EA), the precursor of theanine biosynthesis, is synthesized from alanine decarboxylation by alanine decarboxylase (AlaDC) in tea plants. AlaDC evolves from serine decarboxylase (SerDC) through neofunctionalization and has lower catalytic activity. However, lacking structure information hinders the understanding of the evolution of substrate specificity and catalytic activity. In this study, we solved the X-ray crystal structures of AlaDC from Camellia sinensis (CsAlaDC) and SerDC from Arabidopsis thaliana (AtSerDC). Tyr 341 of AtSerDC or the corresponding Tyr 336 of CsAlaDC is essential for their enzymatic activity. Tyr 111 of AtSerDC and the corresponding Phe 106 of CsAlaDC determine their substrate specificity. Both CsAlaDC and AtSerDC have a distinctive zinc finger and have not been identified in any other Group II PLP-dependent amino acid decarboxylases. Based on the structural comparisons, we conducted a mutation screen of CsAlaDC. The results indicated that the mutation of L110F or P114A in the CsAlaDC dimerization interface significantly improved the catalytic activity by 110% and 59%, respectively. Combining a double mutant of CsAlaDC L110F/P114A with theanine synthetase increased theanine production 672% in an in vitro system. This study provides the structural basis for the substrate selectivity and catalytic activity of CsAlaDC and AtSerDC and provides a route to more efficient biosynthesis of theanine.

Tea seedlings (Camellia sinensis) have a well-developed root system with a strong taproot and lateral roots. Compared with ordinary cuttings, tea has stronger vitality and environmental adaptability, thus facilitating the promotion of good varieties. However, there is less of detailed research on the rooting and germination process of tea seeds. In this study, matrix-assisted laser desorption ionization time-of-flight-mass spectrometry was used to conduct non-targeted spatial mass spectrometry imaging of the main organs during growth of tea seedlings. A total of 1234 compounds were identified, which could be divided into 24 classes. Among them, theanine, as the most prominent nitrogen compound, was synthesized rapidly at the early stage of embryo germination, accounting for >90% of the total free amino acids in the radicle, and it was then transferred to each meristem region through the mesocolumnar sheath, indicating that theanine-based nitrogen flow plays a decisive role in organ formation during the development of tea seedlings. Nutrients stored in the cotyledon were rapidly hydrolyzed to dextrin and 3-phosphoglyceraldehyde at the early stages of germination, and subsequently converted to other forms that provided carbon and energy for development, such as raffinose and d-galactose (glucose), which were mainly distributed in the growing zones of the root apex and the apical meristems of the stem. This study provides a new perspective on the synthesis and metabolism of substances during the development of tea seedlings and contributes to a better understanding of the biological characteristics of tea varieties.

Tea is one of the most popular non-alcoholic beverages, while tea plant is also an important cash crop in the world. Somatic embryogenesis (SE) is a powerful tool for producing large scale vegetative propagation, but the unestablished SE regeneration system greatly impedes the mass production of tea seedlings, and thereby affecting the development of tea industry. In this study, we established a high -efficiency direct SE system in tea including somatic embryo initiation, maturation and germination. Somatic embryo initiation was affected by tea cultivars, explant age and plant growth regulator. Cotyledons of tea seeds at 270 days after flowering had the highest globular embryos induction efficiency as explant. Somatic embryos were induced well in embryos initiation medium adding 1 mg/L NAA and 0.5 mg/L 6 -BA. The optimum induction rate from globular embryos to cotyledonary embryos was 12.62 +/- 1.57%, when the globular embryos was transferred to the hormone -free medium supplemented with 2 g/L activated carbon. Mature embryos germinated to produce plantlet on MS medium with 1 mg/L 6 -BA and 0.1 mg/L NAA with a generation frequency of 20.2 +/- 0.1%. In addition, six SE -related genes were identified, and the expression level of these genes during the SE of tea were analyzed by quantitative realtime RT-PCR (qRT-PCR). These genes showed higher expression level in the initiation embryo stage than maturated embryo stage, which deduced that these genes are crucial during the initiation of SE in tea. Taken together, the establishment of a direct SE regeneration system for tea plant would confer to large-scale propagation and genetic improvement of tea plant as well as studies about SE -related genes would lay the foundation for further clarifying the molecular mechanism of SE in tea plant.