Tea Plant Camellia Sinensis Research Articles

CsXDH1 gene promotes caffeine catabolism induced by continuous strong light in tea plant.

Tea plant (Camellia sinensis) is an important cash crop with extensive adaptability in the world. However, complex environmental factors force a large variation of tea quality-related components. Caffeine is essential for the formation of bitter and fresh flavors in tea, and is the main compound of tea that improves human alertness. Continuous strong light stimulation was observed to cause caffeine reduction in tea leaves, but the mechanism is not clear. In this study, the response of tea plant to light intensity was analysed mainly by multi-omics association, antisense oligodeoxynucleotide (asODN) silencing technique, and in vitro enzyme activity assay. The results revealed multiple strategies for light intensity adaptation in tea plant, among which the regulation of chloroplasts, photosynthesis, porphyrin metabolism, and resistance to oxidative stress were prominent. Caffeine catabolism was enhanced in continuous strong light, which may be a light-adapted strategy due to strict regulation by xanthine dehydrogenase (XDH). asODN silencing and enzymatic activity assays confirmed that CsXDH1 is a protein induced by light intensity to catalyze the substrate xanthine. CsXDH1 asODN silencing resulted in significant up-regulation of both caffeine and theobromine in in vitro enzyme activity assay, but not in vivo. CsXDH1 may act as a coordinator in light intensity adaptation, thus disrupting this balance of caffeine catabolism.

Molecular markers in tea plant (Camellia sinensis): Applications to evolution, genetic identification, and molecular breeding

Tea plants have a long cultivation history in the world, and the beverage (tea) made from its leaves is well known in the world. Due to the characteristics of self-incompatibility, long-term natural and artificial hybridization, tea plants have a very complex genetic background, which make the classification of tea plants unclear. Molecular marker, one type of genetic markers, has the advantages of stable inheritance, large amount of information, and high reliability. The development of molecular marker has facilitated the understanding of complex tea germplasm resources. So far, molecular markers had played important roles in the study of the origin and evolution, the preservation and identification of tea germplasms, and the excellent cultivars breeding of tea plants. However, the information is scattered, making it difficult to understand the advance of molecular markers in tea plants. In this paper, we summarized the development process and types of molecular markers in tea plants. In addition, the application advance of these molecular markers in tea plants was reviewed. Perspectives of molecular markers in tea plants were also systematically provided and discussed. The elaboration of molecular markers in this paper should help us to renew understanding of its application in tea plants.

A comprehensive review of polyphenol oxidase in tea (Camellia sinensis): Physiological characteristics, oxidation manufacturing, and biosynthesis of functional constituents.

Polyphenol oxidase (PPO) is a metalloenzyme with a type III copper core that is abundant in nature. As one of the most essential enzymes in the tea plant (Camellia sinensis), the further regulation of PPO is critical for enhancing defensive responses, cultivating high-quality germplasm resources of tea plants, and producing tea products that are both functional and sensory qualities. Due to their physiological and pharmacological values, the constituents from the oxidative polymerization of PPO in tea manufacturing may serve as functional foods to prevent and treat chronic non-communicable diseases. However, current knowledge of the utilization of PPO in the tea industry is only available from scattered sources, and a more comprehensive study is required to reveal the relationship between PPO and tea obviously. A more comprehensive review of the role of PPO in tea was reported for the first time, as its classification, catalytic mechanism, and utilization in modulating tea flavors, compositions, and nutrition, along with the relationships between PPO-mediated enzymatic reactions and the formation of functional constituents in tea, and the techniques for the modification and application of PPO based on modern enzymology and synthetic biology are summarized and suggested in this article.

The impact of cadmium stress on the ascorbate-glutathione pathway and ascorbate regeneration in tea plants

Ascorbic acid (AsA) and glutathione (GSH) contribute to defense responses under abiotic stresses. The present study explored the ascorbate-glutathione cycle and ascorbate regeneration under high concentration (30 mM) of cadmium in the tea plant (Camellia sinensis L.). The tea leaves showed speckles and necrosis from the third day of Cd treatment. The content of superoxide anion (O2.-) and hydrogen peroxide (H2O2) in the leaves were significantly higher until the seventh day after Cd treatment. The content of O2.- and H2O2 were the highest on the fifth day (212.7 and 153.6 % of the control, respectively). The AsA content increased (86.9 %) on the first day after Cd treatment and decreased significantly in the subsequent days, while GSH showed a reverse trend. The enzymatic activity assays showed that dehydroascorbate reductase (DHAR) and glutathione reductase (GR) involved in AsA regeneration were downregulated considerably after Cd foliar application. In contrast, the activities of ascorbate peroxidase (APX) and monodehydroascorbate reductase (MDHAR) increased on the first day and then declined. Reverse-transcription quantitative PCR showed upregulation of glutathione synthetase (CsGSHS), γ-glutamylcysteine synthetase (Csγ-ECS), and CsMDHAR of the AsA regeneration pathway and downregulation of CsDHAR and CsGR. The expressions of GDP-L-galactose phosphorylase (CsGGP), L-galactose-1-phosphate phosphatase (CsGPP), and L-galactono- 1,4-lactone dehydrogenase (CsGaILDH) of the L-galactose pathway were also downregulated. The results indicated that AsA, which can respond to Cd stress of plants by increasing antioxidant ability, was consumed to scavenge ROS; moreover, Cd stress inhibited AsA synthesis and regeneration, which made that tea plants suffering severe damage.

Topics and trends in fresh tea (Camellia sinensis) leaf research: A comprehensive bibliometric study.

Tea plant (Camellia sinensis) is a widely cultivated cash crop and tea is a favorite functional food in the world. Fresh tea leaves (FTLs) play a critical role in bridging the two fields closely related to tea cultivation and tea processing, those are, tea plant biology and tea biochemistry. To provide a comprehensive overview of the development stages, authorship collaboration, research topics, and hotspots and their temporal evolution trends in the field of FTLs research, we conducted a bibliometric analysis, based on 971 publications on FTLs-related research published during 2001-2021 from Web of Science Core Collection. CiteSpace, R package Bibliometrix, and VOSviewer were employed in this research. The results revealed that the development history can be roughly divided into three stages, namely initial stage, slow development stage and rapid development stage. Journal of Agricultural & Food Chemistry published most articles in this field, while Frontiers in Plant Science held the highest total citations and h-index. The most influential country, institution, and author in this field was identified as China, the Chinese Academy of Agricultural Sciences, and Xiaochun Wan, respectively. FTLs-related research can be categorized into three main topics: the regulation mechanism of key genes, the metabolism and features of essential compounds, and tea plants' growth and stress responses. The most concerning hotspots are the application of advanced technologies, essential metabolites, leaf color variants, and effective cultivation treatments. There has been a shift from basic biochemical and enzymatic studies to studies of molecular mechanisms that depend on multi-omics technologies. We also discussed the future development in this field. This study provides a comprehensive summary of the research field, making it easier for researchers to be informed about its development history, status, and trends.

Green Tea and Benign Gynecologic Disorders: A New Trick for An Old Beverage?

Green tea is harvested from the tea plant Camellia sinensis and is one of the most widely consumed beverages worldwide. It is richer in antioxidants than other forms of tea and has a uniquely high content of polyphenolic compounds known as catechins. Epigallocatechin-3-gallate (EGCG), the major green tea catechin, has been studied for its potential therapeutic role in many disease contexts, including pathologies of the female reproductive system. As both a prooxidant and antioxidant, EGCG can modulate many cellular pathways important to disease pathogenesis and thus has clinical benefits. This review provides a synopsis of the current knowledge on the beneficial effects of green tea in benign gynecological disorders. Green tea alleviates symptom severity in uterine fibroids and improves endometriosis through anti-fibrotic, anti-angiogenic, and pro-apoptotic mechanisms. Additionally, it can reduce uterine contractility and improve the generalized hyperalgesia associated with dysmenorrhea and adenomyosis. Although its role in infertility is controversial, EGCG can be used as a symptomatic treatment for menopause, where it decreases weight gain and osteoporosis, as well as for polycystic ovary syndrome (PCOS).

Identification of circular RNAs in tea plant during Helopeltis theivora infestation

The tea mosquito bug (TMB) or Helopeltis theivora has been reported as a significant tea pest that causes major tea crop loss. Circular RNAs (circRNAs) are a newly discovered group of the non-coding RNA (ncRNA) and are known to function in gene regulation process. Tea plant (Camellia sinensis) has not been explored for the detection of circRNAs during pest infestation. This is the first report of circRNAs identified in C. sinensis infested by a sap-sucking insect H. theivora. In total, we identified 709 circRNAs in six RNA-seq libraries. Analysis of the differential expression pattern revealed that 34 circRNAs got upregulated/downregulated in response to H. theivora attack. Functional annotation and enrichment analysis of the differentially expressed circRNAs showed that the circRNA-target genes were enriched in biological pathways like “tryptophan metabolism”, “biosynthesis of secondary metabolites”, “porphyrin metabolism”, “nucleocytoplasmic transport”, “N-glycan biosynthesis” etc. miRNA-mediated interaction analysis of the circRNAs also showed that 17 differentially expressed circRNAs could also act as “sponges” thus masking the miRNA-mRNA binding and subsequently repressing mRNA cleavage. These differentially expressed circRNAs were predicted to have the capacity to behave as endogenous target mimics (eTMs) for potential genes like aspartyl protease, phospholipase, lectin receptor etc.

Comprehensive analysis of the laccase gene family in tea plant highlights its roles in development and stress responses

BackgroundLaccase (LAC) is the pivotal enzyme responsible for the polymerization of monolignols and stress responses in plants. However, the roles of LAC genes in plant development and tolerance to diverse stresses are still largely unknown, especially in tea plant (Camellia sinensis), one of the most economically important crops worldwide.ResultsIn total, 51 CsLAC genes were identified, they were unevenly distributed on different chromosomes and classified into six groups based on phylogenetic analysis. The CsLAC gene family had diverse intron–exon patterns and a highly conserved motif distribution. Cis-acting elements in the promoter demonstrated that promoter regions of CsLACs encode various elements associated with light, phytohormones, development and stresses. Collinearity analysis identified some orthologous gene pairs in C. sinensis and many paralogous gene pairs among C. sinensis, Arabidopsis and Populus. Tissue-specific expression profiles revealed that the majority of CsLACs had high expression in roots and stems and some members had specific expression patterns in other tissues, and the expression patterns of six genes by qRT‒PCR were highly consistent with the transcriptome data. Most CsLACs showed significant variation in their expression level under abiotic (cold and drought) and biotic (insect and fungus) stresses via transcriptome data. Among them, CsLAC3 was localized in the plasma membrane and its expression level increased significantly at 13 d under gray blight treatment. We found that 12 CsLACs were predicted to be targets of cs-miR397a, and most CsLACs showed opposite expression patterns compared to cs-miR397a under gray blight infection. Additionally, 18 highly polymorphic SSR markers were developed, these markers can be widely used for diverse genetic studies of tea plants.ConclusionsThis study provides a comprehensive understanding of the classification, evolution, structure, tissue-specific profiles, and (a)biotic stress responses of CsLAC genes. It also provides valuable genetic resources for functional characterization towards enhancing tea plant tolerance to multiple (a)biotic stresses.

Understanding the Origin and Evolution of Tea (Camellia sinensis [L.]): Genomic Advances in Tea.

Tea, which is processed by the tender shoots or leaves of tea plant (Camellia sinensis), is one of the most popular nonalcoholic beverages in the world and has numerous health benefits for humans. Along with new progress in biotechnologies, the refined chromosome-scale reference tea genomes have been achieved, which facilitates great promise for the understanding of fundamental genomic architecture and evolution of the tea plants. Here, we summarize recent achievements in genome sequencing in tea plants and review the new progress in origin and evolution of tea plants by population sequencing analysis. Understanding the genomic characterization of tea plants is import to improve tea quality and accelerate breeding in tea plants.

Identification and characterization of Cladosporium species associated with tea plants (Camellia sinensis) in China

AbstractThe tea plant (Camellia sinensis) is widely cultivated worldwide as one of the most popular non‐alcoholic beverage crops. Cladosporium, the dominant endophytic genus of leaves, possesses a variety of biotransformation and metabolic abilities to promote the accumulation of secondary metabolites. However, Cladosporium species in tea leaves remain unexplored. In this study, a total of 79 Cladosporium isolates were obtained from the leaves of several tea varieties in China. Multilocus phylogenetic analysis and morphological characteristics revealed six known species, namely, C. angulosum, C. anthropophilum, C. halotolerans, C. perangustum, C. tenuissimum and C. xanthochromaticum, and one novel species named C. camelliae. C. angulosum was the most dominant species, and the other six species were newly recorded in tea plants. Pathogenicity tests showed no obvious symptoms of disease in tea leaves caused by 13 representative strains of these seven Cladosporium species. Subsequently, three frequently used fungicides were tested, including chlorothalonil, pyraclostrobin and thiophanate‐methyl. The EC50 values against C. tenuissimum were 19.14, 0.548 and 3.796 μg/mL, respectively. Based on these EC50 values, the inhibition effects of the three fungicides on six strains from six species (C. angulosum, C. anthropophilum, C. camelliae, C. perangustum, C. tenuissimum and C. xanthochromaticum) were further compared. Pyraclostrobin had the strongest inhibitory effects on the mycelial growth of Cladosporium, followed by thiophanate‐methyl, and chlorothalonil showed the weakest inhibitory effect. The results provide a basis for understanding endophytic Cladosporium fungi in tea leaves.

Determination of Tea Aroma Precursor Glycosides: An Efficient Approach via Liquid Chromatography-Tandem Mass Spectrometry.

Tea aroma components are often stored as glycosidically bound forms in the tea plant (Camellia sinensis). However, the determination of these glycosides in tea samples is far from optimal. In the present study, we developed a high-performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS) method for simultaneous quantification of eight primary aroma glycosides within 10 min. After systematic optimization of multiple reaction monitoring (MRM) parameters, the proposed method was highly sensitive and accurate. Optimization of the method permitted the efficient extraction of aroma glycosides. The developed method was applied to analyze the contents of aroma glycosides in different organs of tea plants, including the bud, leaves, and stem. Contents of aroma glycosides in the harvested 'Shaancha 1' ranged from 36.1 to 40454.4 μg kg-1. Geranyl glucoside and primeveroside mainly accumulated in young leaves, while other glycosides mainly accumulated in mature leaves. The findings document a rapid, reliable, and efficient analysis method. This method will be helpful in elucidating the biosynthesis and biotransformation mechanism of tea aroma glycosides and in promoting the development of the tea industry using advanced technological control approaches during the cultivation of tea plants and tea manufacture.

Tea plant (Camellia sinensis) lipid metabolism pathway modulated by tea field microbe (Colletotrichum camelliae) to promote disease.

Tea is one of the most popular healthy and non-alcoholic beverages worldwide. Tea anthracnose is a disease in tea mature leaves and ultimately affects yield and quality. Colletotrichum camelliae is a dominant fungal pathogen in the tea field that infects tea plants in China. The pathogenic factors of fungus and the susceptible factors in the tea plant are not known. In this work, we performed molecular and genetic studies to observe a cerato-platanin protein CcCp1 from C. camelliae, which played a key role in fungal pathogenicity. △CcCp1 mutants lost fungal virulence and reduced the ability to produce conidia. Transcriptome and metabolome were then performed and analysed in tea-susceptible and tea-resistant cultivars, Longjing 43 and Zhongcha 108, upon C. camelliae wild-type CCA and △CcCp1 infection, respectively. The differentially expressed genes and the differentially accumulated metabolites in tea plants were clearly overrepresented such as linolenic acid and linoleic acid metabolism, glycerophospholipid metabolism, phenylalanine biosynthesis and metabolism, biosynthesis of flavonoid, flavone and flavonol etc. In particular, the accumulation of jasmonic acid was significantly increased in the susceptible cultivar Longjing 43 upon CCA infection, in the fungal CcCp1 protein dependent manner, suggesting the compound involved in regulating fungal infection. In addition, other metabolites in the glycerophospholipid and phenylalanine pathway were observed in the resistant cultivar Zhongcha 108 upon fungal treatment, suggesting their potential role in defense response. Taken together, this work indicated C. camelliae CcCp1 affected the tea plant lipid metabolism pathway to promote disease while the lost function of CcCp1 mutants altered the fungal virulence and plant response.

Genome-wide characterization of the U-box gene in Camellia sinensis and functional analysis in transgenic tobacco under abiotic stresses

Plants U-box genes are crucial for plant survival, and they extensively regulate plant growth, reproduction and development as well as coping with stress and other processes. In this study, we identified 92 CsU-box genes through genome-wide analysis in the tea plant (Camellia sinensis), all of them contained the conserved U-box domain and were divided into 5 groups, which supported by the further genes structure analysis. The expression profiles in eight tea plant tissues and under abiotic and hormone stresses were analyzed using the TPIA database. 7 CsU-box genes (CsU-box27/28/39/46/63/70/91) were selected to verify and analyze expression patterns under PEG-induced drought and heat stress in tea plant respectively, the qRT-PCR results showed consistent with transcriptome datasets; and the CsU-box39 were further heterologous expressed in tobacco to perform gene function analysis. Phenotypic analyses of overexpression transgenic tobacco seedlings and physiological experiments revealed that CsU-box39 positively regulated the plant response to drought stress. These results lay a solid foundation for studying the biological function of CsU-box, and will provide breeding strategy basis for tea plant breeders.

Influence of Different Precursors on Content of Polyphenols in Camellia sinensis In Vitro Callus Culture

Plant tissue cultures are considered as potential producers of biologically active plant metabolites, which include various phenolic compounds that can be used to maintain human health. Moreover, in most cases, their accumulation is lower than in the original explants, which requires the search for factors and influences for the intensification of this process. In this case, it is very promising to use the precursors of their biosynthesis as potential "regulators" of the various metabolites' formation. The purpose of our research was to study the effect of L-phenylalanine (PhA, 3 mM), trans-cinnamic acid (CA, 1 mM) and naringenin (NG, 0.5 mM), as components of various stages of phenolic metabolism, on accumulation of various phenolic compound classes, including phenylpropanoids, flavans and proanthocyanidins, as well as the content of malondialdehyde in in vitro callus culture of the tea plant (Camellia sinensis L.). According to the data obtained, the precursors' influence did not lead to changes in the morphology and water content of the cultures. At the same time, an increase in the total content of phenolic compounds, as well as phenylpropanoids, flavans and proanthocyanidins, was noted in tea callus cultures. Effectiveness of precursor action depends on its characteristics and the exposure duration, and was more pronounced in the treatments with PhA. This compound can be considered as the most effective precursor regulating phenolic metabolism, contributing to a twofold increase in the total content of phenolic compounds, flavanes and proanthocyanidins, and a fourfold increase in phenylpropanoids in tea callus cultures.

Genome Identification of the Tea Plant (Camellia sinensis) ASMT Gene Family and Its Expression Analysis under Abiotic Stress.

The tea plant (Camellia sinensis (L.) O. Ktze) is an important cash crop grown worldwide. It is often subjected to environmental stresses that influence the quality and yield of its leaves. Acetylserotonin-O-methyltransferase (ASMT) is a key enzyme in melatonin biosynthesis, and it plays a critical role in plant stress responses. In this paper, a total of 20 ASMT genes were identified in tea plants and classified into three subfamilies based on a phylogenetic clustering analysis. The genes were unevenly distributed on seven chromosomes; two pairs of genes showed fragment duplication. A gene sequence analysis showed that the structures of the ASMT genes in the tea plants were highly conserved and that the gene structures and motif distributions slightly differed among the different subfamily members. A transcriptome analysis showed that most CsASMT genes did not respond to drought and cold stresses, and a qRT-PCR analysis showed that CsASMT08, CsASMT09, CsASMT10, and CsASMT20 significantly responded to drought and low-temperature stresses; in particular, CsASMT08 and CsASMT10 were highly expressed under low-temperature stress and negatively regulated in response to drought stress. A combined analysis revealed that CsASMT08 and CsASMT10 were highly expressed and that their expressions differed before and after treatment, which indicates that they are potential regulators of abiotic stress resistance in the tea plant. Our results can facilitate further studies on the functional properties of CsASMT genes in melatonin synthesis and abiotic stress in the tea plant.

Identification of the lysine and histidine transporter family in Camellia sinensis and the characterizations in nitrogen utilization

In plants, the lysine and histidine transporter (LHT) family represent a class of proteins that mediate the uptake, translocation, and utilization of amino acids. The tea plant (Camellia sinensis) is a perennial evergreen with a relatively high level of amino acids. However, systematic identification and molecular characterization of the LHT gene family has rarely been reported in tea plants. In this study, 22 CsLHTs were identified from the ‘Shuchazao’ genome and classified into two groups. The modeled three-dimensional structure and the conserved domains presented a high similarity among the LHTs proteins. Moreover, it was predicted that a few genes were conserved through the analysis of the physiochemical characters, structures and cis-elements in promoters. The expression patterns in tea plants revealed that CsLHT7 was mainly expressed in the roots, and CsLHT4 and CsLHT11 exhibited relatively high expression in both the roots and leaves. Moreover, the expression of all three genes could be induced by organic nitrogen. Additionally, heterogeneous expression of CsLHT4, CsLHT7 and CsLHT11 in Arabidopsis thaliana decreased the aerial parts biomass compared with that in WT plants while significantly increased the rosette biomass only for CsLHT11 transgenic plants versus WT plants. Overall, our results provide fundamental information about CsLHTs and potential genes in N utilization for further analysis in tea plants.

Green Tea in Reproductive Cancers: Could Treatment Be as Simple?

Green tea originates from the tea plant Camellia sinensis and is one of the most widely consumed beverages worldwide. Green tea polyphenols, commonly known as catechins, are the major bioactive ingredients and account for green tea's unique health benefits. Epigallocatechin-3-gallate (EGCG), is the most potent catechin derivative and has been widely studied for its pro- and anti-oxidative effects. This review summarizes the chemical and chemopreventive properties of green tea in the context of female reproductive cancers. A comprehensive search of PubMed and Google Scholar up to December 2022 was conducted. All original and review articles related to green tea or EGCG, and gynecological cancers published in English were included. The findings of several in vitro, in vivo, and epidemiological studies examining the effect of green tea on reproductive cancers, including ovarian, cervical, endometrial, and vulvar cancers, are presented. Studies have shown that this compound targets specific receptors and intracellular signaling pathways involved in cancer pathogenesis. The potential benefits of using green tea in the treatment of reproductive cancers, alone or in conjunction with chemotherapeutic agents, are examined, shedding light on new therapeutic strategies for the management of female reproductive cancers.

An undefined cystatin CsCPI1 from tea plant Camellia sinensis harbors antithrombotic activity

Tea consumption has been linked to a decreased risk of cardiovascular disease (CVD) mortality, which imposes a heavy burden on the healthcare system; however, which components in tea cause this beneficial effect is not fully understood. Here we uncovered a cystatin (namely CsCPI1), which is a cysteine proteinase inhibitor (CPI) of the tea plant (Camellia sinensis) that promotes antithrombotic activity. Since thrombosis is a common pathogenesis of fatal CVDs, we investigated the effects of CsCPI1, which showed good therapeutic effects in mouse models of thrombotic disease and ischemic stroke. CsCPI1 significantly increases endothelial cell production of nitric oxide (NO) and inhibits platelet aggregation. Notably, CsCPI1 exhibited no cytotoxicity or resistance to pH and temperature changes, which indicates that CsCPI1 might be a potent antithrombotic agent that contributes to the therapeutic effects of tea consumption against CVD. Specifically, the antithrombotic effects of CsCPI1 are distinct from the classical function of plant cystatins against herbivorous insects. Therefore, our study proposes a new potential role of cystatins in CVD prevention and treatment, which requires further study.

Evolutionary Landscape of Tea Circular RNAs and Its Contribution to Chilling Tolerance of Tea Plant.

Chilling stress threatens the yield and distribution pattern of global crops, including the tea plant (Camellia sinensis), one of the most important cash crops around the world. Circular RNA (circRNA) plays roles in regulating plant growth and biotic/abiotic stress responses. Understanding the evolutionary characteristics of circRNA and its feedbacks to chilling stress in the tea plant will help to elucidate the vital roles of circRNAs. In the current report, we systematically identified 2702 high-confidence circRNAs under chilling stress in the tea plant, and interestingly found that the generation of tea plant circRNAs was associated with the length of their flanking introns. Repetitive sequences annotation and DNA methylation analysis revealed that the longer flanking introns of circRNAs present more repetitive sequences and higher methylation levels, which suggested that repeat-elements-mediated DNA methylation might promote the circRNAs biogenesis in the tea plant. We further detected 250 differentially expressed circRNAs under chilling stress, which were functionally enriched in GO terms related to cold/stress responses. Constructing a circRNA-miRNA-mRNA interaction network discovered 139 differentially expressed circRNAs harboring potential miRNA binding sites, which further identified 14 circRNAs that might contribute to tea plant chilling responses. We further characterized a key circRNA, CSS-circFAB1, which was significantly induced under chilling stress. FISH and silencing experiments revealed that CSS-circFAB1 was potentially involved in chilling tolerance of the tea plant. Our study emphasizes the importance of circRNA and its preliminary role against low-temperature stress, providing new insights for tea plant cold tolerance breeding.

Transcriptome analysis reveals CsGSTU18 plays an important role in anthocyanin accumulation-induced tender shoot turning purple of tea plant (Camellia sinensis)

Tea plant (Camellia sinensis) is a natural health drink. Because of its unique taste and the health-care effects of natural products, tea is more and more popular and concerned with people. Under the conditions of high temperature and strong light, the young leaves of tea plants are prone to accumulate anthocyanins, which in turn affects the suitability and quality of tea leaves. Here, we screened a key significantly up-regulated glutathione S-transferase 18 (CsGSTU18) gene from both cultivars ‘Zi 1’ (Z1) and ‘Shaanxi Ziyang’ (SZ) by RNA-seq. CsGSTU18, which belongs to Tau subfamily, was localized in the endoplasmic reticulum and cytoplasm. The overexpression of CsGSTU18 enhanced anthocyanin accumulation in transgenic Arabidopsis and rescued the anthocyanin-deficient phenotype of strawberry reduced anthocyanins in petioles (rap) mutant. Antisense oligonucleotide (asODN)-mediated transient silencing of CsGSTU18 significantly reduced anthocyanin accumulation in tea plant leaves, whereas the transient overexpression of CsGSTU18 showed the opposite change trend. Overall, these findings suggest that CsGSTU18 plays an important role in anthocyanin accumulation, which result in the tea tender shoot turning purple. This study provides a basis for further research on the molecular mechanism of anthocyanin accumulation in tea plant.