Abstract
Wild teas are valuable genetic resources for studying domestication and breeding. Here we report the assembly of a high-quality chromosome-scale reference genome for an ancient tea tree. The ...further RNA sequencing of 217 diverse tea accessions clarifies the pedigree of tea cultivars and reveals key contributors in the breeding of Chinese tea. Candidate genes associated with flavonoid biosynthesis are identified by genome-wide association study. Specifically, diverse allelic function of
CsANR
,
CsF3’5’H
and
CsMYB5
is verified by transient overexpression and enzymatic assays, providing comprehensive insights into the biosynthesis of catechins, the most important bioactive compounds in tea plants. The inconspicuous differentiation between ancient trees and cultivars at both genetic and metabolic levels implies that tea may not have undergone long-term artificial directional selection in terms of flavor-related metabolites. These genomic resources provide evolutionary insight into tea plants and lay the foundation for better understanding the biosynthesis of beneficial natural compounds.
Fungi are generally thought to live in host plants with a single lifestyle, being parasitism, commensalism, or mutualism. The former, known as phytopathogenic fungi, cause various plant diseases that ...result in significant losses every year; while the latter, such as endophytic fungi, can confer fitness to the host plants. It is unclear whether biological factors can modulate the parasitic and mutualistic traits of a fungus. In this study, we isolated and characterized a mycovirus from an endophytic strain of the fungus Pestalotiopsis theae, a pathogen of tea (Camellia sinensis). Based on molecular analysis, we tentatively designated the mycovirus as Pestalotiopsis theae chrysovirus-1 (PtCV1), a novel member of the family Chrysoviridae, genus Alphachrysovirus. PtCV1 has four double-stranded (ds) RNAs as its genome, ranging from 0.9 to 3.4 kbp in size, encapsidated in isometric particles. PtCV1 significantly reduced the growth rates of its host fungus in vitro (ANOVA; P-value < 0.001) and abolished its virulence in planta (ANOVA; P-value < 0.001), converting its host fungus to a non-pathogenic endophyte on tea leaves, while PtCV1-free isolates were highly virulent. Moreover, the presence of PtCV1 conferred high resistance to the host plants against the virulent P. theae strains. Here we report a mycovirus that modulates endophytic and phytopathogenic fungal traits and provides an alternative approach to biological control of plant diseases caused by fungi.
•Steeping temperature affects the main composition of green tea infusions.•Green tea steeped at 100°C shows the highest antioxidant activity.•It also exhibits the highest α-amylase and α-glucosidase ...inhibitory activities.•Green tea steeped at 60°C shows the highest glucose uptake inhibition.
The objective of the present study was to evaluate the effect of steeping temperature on the biological activities of green tea, including the 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical-scavenging capacity, α-glucosidase and α-amylase inhibitory activities, and glucose uptake inhibitory activity in Caco-2 cells. Results showed that, with increasing extraction temperature, the polyphenol content increased, which contributed to enhance antioxidant activity and inhibitory effects on α-glucosidase and α-amylase. Green tea steeped at 100°C showed the highest DPPH radical-scavenging activity and inhibitory effects on α-glucosidase and α-amylase activities with EC50 or IC50 values of 6.15μg/mL, 0.09mg/mL, and 6.31mg/mL, respectively. However, the inhibitory potential on glucose uptake did not show an upward trend with increasing extraction temperature. Green tea steeped at 60°C had significantly stronger glucose uptake inhibitory activity (p<0.05). The integrated data suggested that steeping temperature should be considered when evaluating the biological activities of green tea.
The tea plant (Camellia sinensis (L.) O. Kuntze) is one of the most economically significant crops worldwide because of its positive effects on human health. The health benefits of tea are mainly ...attributed to catechins, which are the predominant polyphenols that accumulate in tea. Catechins are products of the phenylpropanoid and flavonoid biosynthetic pathways. Although catechins were identified in tea leaves long ago, the molecular mechanisms regulating catechins biosynthesis remain unclear. To identify candidate genes involved in catechins biosynthesis, we analyzed the transcriptomes of tea leaves during five different leaf stages of development using RNA-seq. Approximately 809 million high-quality reads were obtained, trimmed, and assembled into 299,113 unigenes with an average length of 565 bp. A total of 15,817 unigenes were differentially expressed during the different stages of leaf development. These differentially expressed genes were enriched in a variety of processes such as the regulation of the cell cycle, starch and sucrose metabolism, photosynthesis, phenylpropanoid biosynthesis, phenylalanine metabolism, and flavonoid biosynthesis. Based on their annotations, 51 of these differentially expressed unigenes are involved in phenylpropanoid and flavonoid biosynthesis. Furthermore, transcription factors such as MYB, bHLH and MADS, which may involve in the regulation of catechins biosynthesis, were identified through co-expression analysis of transcription factors and structural genes. Real-time PCR analysis of candidate genes indicated a good correlation with the transcriptome data. These findings increase our understanding of the molecular mechanisms regulating catechins biosynthesis in the tea plant.
•Flower-like silver nanostructures have been successfully synthesized via liquid phase reduction method, which has tremendous “hot spots” than regular structure.•It is found that the proper coating ...degree of surfactant on silver nuclei leads to anisotropic growth of the silver nuclei resulting in the formation of flower-like structure with more protrusions.•Flower-like silver nanostructures described in this work exhibit high SERS activity and excellent stability, which can serve as an effective SERS substrate for caffeine.•The average intensity of caffeine SERS signals at 807cm−1(NCH), 958cm−1(Pyrimidine ring) and 1327cm−1 (Imidazole trigonal ring) linear decreased with the −log10C (C is the concentration of caffeine), and the coefficient of determination (R2) is as high as 0.975.
Flower-like silver nanoparticles, with diameters of 450–500nm and protrusions on the surface up to 10–15nm, have been successfully synthesized via liquid phase reduction method, by using ascorbic acid as a reductant and polyvinyl pyrrolidone (PVP) as a surfactant. It is found that the proper coating degree of PVP on silver nuclei leads to anisotropic growth of the silver nuclei resulting in the formation of flower-like structure with more protrusions. Furthermore, when the obtained flower-like silver nanostructure is used as Surface Enhanced Raman Scattering(SERS) substrates, SERS signal is still clearly even if the concentration of R6G solution is reduced down to 10−8M. The SERS enhancement mechanism of flower-like silver nanostructures in SERS spectroscopy has been further discussed. SERS technology based on the obtained flower-like silver nanostructure substrates can be also used as an effective way to detect caffeine. In this work, it is found that the average intensity of SERS signals at 807cm−1(NCH), 958cm−1(Pyrimidine ring) and 1327cm−1(Imidazole trigonal ring) linear decreased with the −log10C (C is the concentration of caffeine), and the coefficient of determination (R2) is as high as 0.975. This work provides a new way for the quantitative detection of caffeine based on SERS spectroscopy.
•Flower-shaped silver nanostructures obtained were used as stable SERS substrates with high SERS activity.•SERS spectroscopy of four different food colorants were analyzed and the characteristic ...bands were identified.•An improved principle component analysis (PCA) was used for four different food colorants detection, at concentrations down to about 10−8M.
Surface Enhanced Raman Scattering (SERS) spectroscopy technology is widely used in materials analysis, environmental monitoring, biomedical, food security and other fields. Flower-shaped silver nanoparticles have been successfully synthesized by a simple aqueous phase silver nitrate reduction by ascorbic acid in the presence of polyvinylpyrrolidone (PVP) surfactant. The nanoparticles diameters were adjusted from 450 to 1000nm with surface protrusions up to 10–25nm. The flower-shaped silver nanostructures obtained were used as stable SERS substrates with high SERS activity for detecting Rhodamine 6G (R6G), at a concentration of only 10−9mol/L, where the SERS signal is still clear. SERS spectroscopy of four different food colorants (e.g. food blue, tartrazine, sunset yellow, acid red) were analysed and the characteristic bands were identified. An improved principle component analysis (PCA) was used for four different food colorants detection, at concentrations down to about 10−8mol/L. Thus, the LOD of food blue, tartrazine, sunset yellow and acid red are 79.285μg/L, 5.3436μg/L, 45.238μg/L and 50.244μg/L, respectively.
Six Green tea powders (GTPs) were prepared from green tea with superfine grinding process. Their main quality components were determined by chemical methods and the scavenging effects of GTPs on ·OH ...and O2.−in vitro were evaluated by using deoxyribose assay and xanthine oxidase method, respectively. The results indicated that tea polyphenols and catechins contents decreased, while the contents of water-soluble carbohydrates in GTPs increased markedly, and no significant difference in amino acids and caffein with the decrease in particle size during superfine grinding, which benefited to reduce bitterness and preserve briskness of GTPs. Meanwhile, superfine grinding increased extraction of TPS markedly, which could lead to more potent scavenging capacity of GTPEs on ·OH. Based on the above analysis, it suggested that superfine grinding time should be controlled within 30–50 min, with ideal parameters of GTP: X: 4.93–4.75%, d50: 20.3–13.5 μm, ρbulk: 0.323–0.297 kg/m3, ρtapped: 0.666–0.614 kg/m3. Under this condition, we could prepare GTP with green and bright color, narrower and more uniform particle size distribution, as well as possessing more food processing property.
► Different particle size GTPs were prepared with the same green tea material. ► The content of soluble sugar, and tea polysaccharide extraction yield increased. ► The content of catechins dropped during superfine grinding. ► Superfine grinding increased potent scavenging capacity of GTPEs on ·OH. ► Superfine grinding time should be controlled within 30–50 min.
The major aluminum (Al) detoxication mechanism of tea plant (Camellia sinensis), as an Al hyperaccumulator plant, is the fixation of almost 70% of Al in the cell walls. Pectin is the primary ...constituent of cell walls, a degree of methylation of pectin polysaccharides regulated by the pectin methylesterase (PME) genes can greatly affect the Al binding capacity. The knowledge on PME gene family in tea plant is still poor. We identified 66 (CsPME1-CsPME66) PME genes from C. sinensis genome. We studied their protein characterization, conserved motifs, gene structure, systematic evolution and gene expression under Al treatments, to establish a basis for in-depth research on the function of PMEs in tea plant. Gene structures analysis revealed that the majority of PME genes had 2-4 exons. Phylogenetic results pointed out that the PME genes from the same species displayed comparatively high sequence consistency and genetic similarity. Selective pressure investigation suggested that the Ka/Ks value for homologous genes of PME family was less than one. The expression of CsPMEs under three Al concentration treatments was tissue specific, eight PME genes in leaves and 15 in roots displayed a trend similar to of the Al contents and PME activities under Al concentration treatments, indicating that the degree of pectin de-esterification regulated by PME was crucial for Al tolerance of tea plant. Sixty-six CsPME genes were identified for the first time in tea plant. The genome-wide identification, classification, evolutionary and transcription analyses of the PME gene family provided a new direction for further research on the function of PME gene in Al tolerance of tea plant.
Heat stress factors (Hsfs) play vital roles in signal transduction pathways operating in responses to environmental stresses. However, Hsf gene family has not been thoroughly explored in tea plant ...(Camellia sinensis L.).
In this study, we identified 25 CsHsf genes in C. sinensis that were separated by phylogenetic analysis into three sub-families (i.e., A, B, and C). Gene structures, conserved domains and motifs analyses indicated that the CsHsf members in each class were relatively conserved. Various cis-acting elements involved in plant growth regulation, hormone responses, stress responses, and light responses were located in the promoter regions of CsHsfs. Furthermore, degradome sequencing analysis revealed that 7 CsHsfs could be targeted by 9 miRNAs. The expression pattern of each CsHsf gene was significantly different in eight tissues. Many CsHsfs were differentially regulated by drought, salt, and heat stresses, as well as exogenous abscisic acid (ABA) and Ca
. In addition, CsHsfA2 was located in the nucleus. Heterologous expression of CsHsfA2 improved thermotolerance in transgenic yeast, suggesting its potential role in the regulation of heat stress response.
A comprehensive genome-wide analysis of Hsf in C. sinensis present the global identification and functional prediction of CsHsfs. Most of them were implicated in a complex gene regulatory network controlling various abiotic stress responses and signal transduction pathways in tea plants. Additionally, heterologous expression of CsHsfA2 increased thermotolerance of transgenic yeast. These findings provide new insights into the functional divergence of CsHsfs and a basis for further research on CsHsfs functions.
Surface-enhanced Raman spectroscopy is an alternative detection tool for monitoring food security. However, there is still a lack of a conclusion of SERS detection with respect to pesticides and real ...sample analysis, and the summary of intelligent algorithms in SERS is also a blank. In this review, a comprehensive report of pesticides detection using SERS technology is given. The SERS detection characteristics of different types of pesticides and the influence of substrate on inspection are discussed and compared by the typical ways of classification. The key points, including the progress in real sample analysis and Raman data processing methods with intelligent algorithm, are highlighted. Lastly, major challenges and future research trends of SERS analysis of pesticide residue are also addressed. SERS has been proven to be a powerful technique for rapid test of residue pesticides in complex food matrices, but there still is a tremendous development space for future research.
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