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The voltage-gated chloride channel (CLC) superfamily is one of the most important anion channels that is widely distributed in bacteria and plants. CLC is involved in transporting various anions such as chloride (Cl-) and fluoride (F-) in and out of cells. Although Camellia sinensis is a hyper-accumulated F plant, there is no studies on the CLC gene superfamily in the tea plant. Here, 8 CLC genes were identified from C. sinensis and they were named CsCLC1-8. The structure of CsCLC genes and the proteins were not conserved; the number of exons varied from 3 to 24, and the number of transmembrane domains contained 2 to 10. Furthermore, phylogenetic analysis revealed that CsCLC4-8 in subclass I contained the typical conserved domains GxGIPE (I), GKxGPxxH (II) and PxxGxLF (III), and CsCLC1-3 in subclass II did not contain any of the three conserved residues. We measured the expression levels of CsCLCs in roots, stems and leaves to assess the responses to different concentrations of Cl- and F-. The result indicated that CsCLCs participated in subfunctionalization in response to Cl- and F-, and CsCLC1-3 was more sensitive to F- treatments than CsCLC4-8, CsCLC6 and CsCLC7 may participate in absorption and long-distance transport of Cl-. [ABSTRACT FROM AUTHOR]

Salt stress is one of the major environmental constraints for the production and yield of grape (Vitis vinifera) worldwide. The SOS3 gene family is part of the Salt Overly Sensitive (SOS) signaling pathway, a well-defined signaling pathway known to play a role in plant response to salt stress. In this study, the grapevine SOS3 gene family was annotated and the role of the annotated genes in salinity stress response was characterized. Nine grapevine SOS3 genes was identified in the grapevine genome and was subsequently analyzed. The expression patterns of the nine VviSOS3 genes, as determined by reverse transcription quantitative PCR (RT-qPCR), varied greatly in leaves, roots, and stems of in-vitro grown Pinot noir grapevine cultivar(PN40024) in response to salt (250mM NaCl) and polyethylene glycol 6000 (PEG, osmolality equal to the salt treatment) treatments over a 36h time period. All of the VviSOS3 genes, except VviSOS3.7, were up-regulated in leaves in response to the salt and PEG treatments. The majority of VviSOS3 genes, except VviSOS3.8 were up-regulated in roots in response to the PEG stress, with an opposite expression pattern in the root and stem in response to salt stress. The salinity treatment decreased the soluble protein content. Based on the expression pattern and physiological data, VviSOS3.7 and VviSOS3.8 were identified as candidate genes for further functional characterizations regarding their role in the response of grapevine to salt stress. [ABSTRACT FROM AUTHOR]

Transcription factors C-repeat/dehydration-responsive element binding proteins (CBF/DREB) play an important role in plant response to abiotic stresses. Over-expression of various CBF/DREB genes in diverse plants have been reported, but inconsistency of gene donor, recipient genus, parameters used in evaluating the transgenic plants have made it difficult to elucidate the complex physiological mechanisms by which DREBs impact drought tolerance. We performed a meta -analysis to categorize the response of plant parameters involved in drought tolerance in DREB -overexpressed plants and to evaluate experimental variables that affects transgenic plant performance. The results from across different studies indicated that 8 and 2 of 13 measured parameters exhibited a significant response by increasing or decreasing values by 25% or more in drought-stressed and in non-stressed, control plants, respectively. Among the examined moderating variables, promoters, type of media and stress, donor genus, and recipient genus significantly affected the extent of DREBs' influence. In plants subjected to drought stress, the overexpression of DREB genes derived from Arabidopsis led to greater increases in Fv/Fm (maximum quantum efficiency of photosystem II), relative water content, and proline content. These findings should guide future research on the function of the DREB genes in plant drought tolerance and the use of genetic engineering in drought tolerance breeding. [ABSTRACT FROM AUTHOR]

Intercropping is a widely recognised technique that contributes to agricultural sustainability. While intercropping leguminous green manure offers advantages for soil health and tea plants growth, the impact on the accumulation of theanine and soil nitrogen cycle are largely unknown. The levels of theanine, epigallocatechin gallate and soluble sugar in tea leaves increased by 52.87% and 40.98%, 22.80% and 6.17%, 22.22% and 29.04% in intercropping with soybean–Chinese milk vetch rotation and soybean alone, respectively. Additionally, intercropping significantly increased soil amino acidnitrogen content, enhanced extracellular enzyme activities, particularly β‐glucosidase and N‐acetyl‐glucosaminidase, as well as soil multifunctionality. Metagenomics analysis revealed that intercropping positively influenced the relative abundances of several potentially beneficial microorganisms, including Burkholderia, Mycolicibacterium and Paraburkholderia. Intercropping resulted in lower expression levels of nitrification genes, reducing soil mineral nitrogen loss and N2O emissions. The expression of nrfA/H significantly increased in intercropping with soybean–Chinese milk vetch rotation. Structural equation model analysis demonstrated that the accumulation of theanine in tea leaves was directly influenced by the number of intercropping leguminous green manure species, soil ammonium nitrogen and amino acid nitrogen. In summary, the intercropping strategy, particularly intercropping with soybean–Chinese milk vetch rotation, could be a novel way for theanine accumulation. Summary statement: The theanine content of tea leaves increased by 52.87% and 40.98% when intercropped with soybean–Chinese milk vetch rotation and soybean alone, respectively. The accumulation of theanine in tea leaves was directly influenced by the intercropping green manure species and their quantity, as well as the levels of soil ammonium nitrogen and amino acid nitrogen. [ABSTRACT FROM AUTHOR]

AbstractMental contrasting is a motivational behavior change strategy necessary for strong goal commitment. Meanwhile, general causality orientations are motivational patterns that represent individuals’ motivation for behavior change and the reason for their goal commitment. The current study explored whether causality orientations predict spontaneous mental contrasting in Chinese university students. Study 1 investigated whether academic autonomy, control, and amotivated orientations correlate with spontaneous mental contrasting about an important academic goal. The findings of Study 1 reveal that autonomy orientation did not correlate with mental contrasting, whereas control and amotivated orientations were negatively correlated with mental contrasting. Study 2 investigated whether priming autonomy and control orientations, in addition to the neutral condition, would induce spontaneous mental contrasting about an academic goal related to the students’ research topic. The results of Study 2 revealed that the autonomy condition orientation did not differ significantly from the controlled orientation condition. However, when compared to the neutral condition, the autonomy condition significantly predicted mental contrasting, whereas the controlled orientation condition did not show any significant difference. In Study 2, the autonomy-oriented participants generated more spontaneous mental contrast than the control orientation and neutral conditions. The findings show that controlled and amotivated orientations predicted negative mental contrasting. As a result, controlled and amotivated students must learn how to use mental contrasting to achieve high levels of goal commitment and achievement. Lastly, the study discussed its implications, limitations, and suggestions for future research. [ABSTRACT FROM AUTHOR]

Microorganisms play essential roles in soil-ecosystem multifunctionality. However, the contribution of their community assembly processes, composition, diversity, and keystone species to ecosystem multifunctionality is unclear, especially in tea-plantation ecosystems. In order to assess the effects of various intercropping patterns (tea-plant monoculture and tea plants, respectively, intercropped with soybean, soybean—milk vetch, soybean—red clover, and soybean—smooth vetch) on soil rare and abundant taxa, a field experiment was carried out. We found that tea plantation intercropping with legumes improved the soil-ecosystem multifunctionality by altering the soil environment, and ultimately benefited nutrient absorption and quality improvement of tea leaves. Whether it was in bacteria or fungi, rare taxa had a higher proportion of deterministic processes in community assembly than abundant taxa. Additionally, intercropping practices changed the soil environment, and rare bacterial taxa were assembled and shifted from variable selection to homogeneous dispersal. Intercropping practices significantly changed the bacterial and fungal communities' composition, and rare taxa had higher α-diversity than abundant taxa. Increasing legume species in intercropping practice enhanced community dissimilarity to the tea monoculture by affecting soil pH, ammonium nitrogen, and nitrate nitrogen. Rare bacterial and fungal β-diversity exhibited stronger positive relationships with ecosystem multifunctionality (both average and multi-threshold approaches) compared to the corresponding abundant taxa. Furthermore, ecosystem multifunctionality under different intercropping practices was closely related to the keystone rare operational taxonomic units, especially rare bacterial species of Chloroflexi. Our results emphasize the disparate feedbacks of rare and abundant taxa to diverse intercropping practices, as well as the important connection between rare bacterial taxa and ecosystem multifunctionality. [ABSTRACT FROM AUTHOR]

Intercropping has been recommended as a beneficial cropping practice for improving soil characteristic and tea quality. However, there is limited research on the effects of intercropping fruit trees on soil chemical properties, soil aggregate structure, and tea quality components. In this study, intercropping fruit trees, specifically loquats and citrus, had a significant impact on the total available nutrients, AMN, and AP in soil. During spring and autumn seasons, the soil large-macroaggregates (>2 mm) proportion increased by 5.93% and 19.03%, as well as 29.23% and 19.14%, respectively, when intercropping loquats and citrus. Similarly, intercropping waxberry resulted in a highest small-macroaggregates (0.25 mm–2 mm) proportion at 54.89% and 77.32%. Soil aggregate stability parameters of the R 0.25 , MWD, and GMD were generally considered better soil aggregate stability indicators, and significantly improved in intercropping systems. Intercropping waxberry with higher values for those aggregate stability parameters and lower D values, showed a better soil aggregate distribution, while intercropping loquats and citrus at higher levels of AMN and AP in different soil aggregate sizes. As the soil aggregate sizes increased, the AMN and AP contents gradually decreased. Furthermore, the enhanced levels of amino acids were observed under loquat, waxberry, and citrus intercropping in spring, which increased by 27.98%, 27.35%, and 26.21%, respectively. The contents of tea polyphenol and caffeine were lower under loquat and citrus intercropping in spring. These findings indicated that intercropping fruit trees, specifically loquat and citrus, have immense potential in promoting the green and sustainable development of tea plantations. • Intercropping fruit trees increase soil total available nutrients, AMN and AP. • Intercropping loquat and citrus significant increase >2 mm soil large aggregate. • Intercropping waxberry showed a better distribution of soil aggregates. • Intercropping loquat and citrus increase AMN and AP in different aggregate sizes. • Intercropping enhanced tea quality, especially intercropping loquat and citrus in spring. [ABSTRACT FROM AUTHOR]

Ancient tea plants black tea (ATBT) has outstanding sweet-mellow taste, but what contributes to its quality remains unclear. We tested 36 freeze and 9 finished tea sampled from five processing stages for ATBT by electronic tongue (ET), high performance liquid chromatography, and gas chromatography-tandem mass spectrometry. ET and chromatographic data revealed variation of sensory characteristics and chemical compounds among the five processing steps of ATBT. Through the correlation analysis and principal component analysis, it was concluded that ester-catechins and soluble sugars content in tea leaves had significant effect with the bitterness and sweetness in tea infusions (p < 0.05). Catechins, theaflavins, soluble sugars, and ET signals was considered an important information for determining the processing steps, and it had an impact on the taste of the tea infusions. These findings indicated that accurate processing control is effective approach to maintaining chemical constituents of contributes to taste quality in ATBT. [Display omitted] • The changes of taste metabolites during ATBT processing were firstly revealed. • Monosaccharides contribute to the sweet taste of ATBT. • Theaflavins contribute to the mellow taste of ATBT. • Ester-catechin was negatively correlated with the sweetness of the tea infusion. [ABSTRACT FROM AUTHOR]

Background: Intercropping, especially with legumes, as a productive and sustainable system, can promote plants growth and improves the soil quality than the sole crop, is an essential cultivation pattern in modern agricultural systems. However, the metabolic changes of secondary metabolites and the growth in tea plants during the processing of intercropping with soybean have not been fully analyzed. Results: The secondary metabolomic of the tea plants were significant influence with intercropping soybean during the different growth stages. Especially in the profuse flowering stage of intercropping soybean, the biosynthesis of amino acids was significantly impacted, and the flavonoid biosynthesis, the flavone and flavonol biosynthesis also were changed. And the expression of metabolites associated with amino acids metabolism, particularly glutamate, glutamine, lysine and arginine were up-regulated, while the expression of the sucrose and D-Glucose-6P were down-regulated. Furthermore, the chlorophyll photosynthetic parameters and the photosynthetic activity of tea plants were higher in the tea plants-soybean intercropping system. Conclusions: These results strengthen our understanding of the metabolic mechanisms in tea plant's secondary metabolites under the tea plants-soybean intercropping system and demonstrate that the intercropping system of leguminous crops is greatly potential to improve tea quality. These may provide the basis for reducing the application of nitrogen fertilizer and improve the ecosystem in tea plantations. [ABSTRACT FROM AUTHOR]

Background: Intercropping, especially with legumes, as a productive and sustainable system, can promote plants growth and improves the soil quality than the sole crop, is an essential cultivation pattern in modern agricultural systems. However, the metabolic changes of secondary metabolites and the growth in tea plants during the processing of intercropping with soybean have not been fully analyzed. Results: The secondary metabolomic of the tea plants were significant influence with intercropping soybean during the different growth stages. Especially in the profuse flowering stage of intercropping soybean, the biosynthesis of amino acids was significantly impacted, and the flavonoid biosynthesis, the flavone and flavonol biosynthesis also were changed. And the expression of metabolites associated with amino acids metabolism, particularly glutamate, glutamine, lysine and arginine were up-regulated, while the expression of the sucrose and D-Glucose-6P were down-regulated. Furthermore, the chlorophyll photosynthetic parameters and the photosynthetic activity of tea plants were higher in the tea plants-soybean intercropping system. Conclusions: These results strengthen our understanding of the metabolic mechanisms in tea plant's secondary metabolites under the tea plants-soybean intercropping system and demonstrate that the intercropping system of leguminous crops is greatly potential to improve tea quality. These may provide the basis for reducing the application of nitrogen fertilizer and improve the ecosystem in tea plantations. [ABSTRACT FROM AUTHOR]

Polyphenols are important active components in tea plants, which have strong biological activity and antioxidant activity. A certain degree of stress or exogenous substances can significantly increase the content of polyphenols in plants. γ-Aminobutyric acid (GABA), a natural functional amino acid, was used to study whether exogenous GABA can increase the content of polyphenols and enhance antioxidant activity in tea plants under heat-stress conditions. The results showed that the content of GABA was positively correlated with the content of polyphenols (r = 0.649), especially with the content of total catechins (r = 0.837). Most of the related genes encoding flavonoid metabolism (PAL, C4H, 4CL , CHS, CHI, F3H, F3′H, F3′5′H, DFR, LAR, ANS , ANR and FLS) as well as enzyme activities (PAL, C4H and 4CL) were upregulated. In addition, the activities of antioxidant enzymes were induced under heat-stress conditions. However, 3-mercaptopropionic acid (3-MPA), an inhibitor of GABA synthesis, exhibited opposite results under heat-stress conditions compared with GABA treatment. These results indicated that GABA plays a key role in the accumulation of polyphenols and the upregulation of the antioxidant system in tea plants under heat-stress conditions. • Exogenous GABA greatly contributed to catechin accumulation in tea. • Exogenous GABA actively induced increased POD, CAT and APX activities. • The catechin biosynthesis related genes were upregulated induced by GABA. [ABSTRACT FROM AUTHOR]

Tea plant often suffers from low temperature induced damage during its growth. How to improve the cold resistance of tea plant is an urgent problem to be solved. Nitric oxide (NO), γ-aminobutyric acid (GABA) and proline have been proved that can improve the cold resistance of tea plants, and signal transfer and biosynthesis link between them may enhance their function. NO is an important gas signal material in plant growth, but our understanding of the effects of NO on the GABA shunt, proline and NO biosynthesis are limited. In this study, the tea roots were treated with a NO donor (SNAP), NO scavenger (PTIO), and NO synthase inhibitor (L-NNA). SNAP could improve activities of arginine decarboxylase, ornithine decarboxylase, glutamate decarboxylase, GABA transaminase and Δ1-pyrroline-5-carboxylate synthetase and the expression level of related genes during the treatments. The contents of putrescine and spermidine under SNAP treatment were 45.3% and 37.3% higher compared to control at 24 h, and the spermine content under PTIO treatment were 57.6% lower compare to control at 12 h. Accumulation of proline of SNAP and L-NNA treatments was 52.2% and 43.2% higher than control at 48 h, indicating other pathway of NO biosynthesis in tea roots. In addition, the NO accelerated the consumption of GABA during cold storage. These facts indicate that NO enhanced the cold tolerance of tea, which might regulate the metabolism of the GABA shunt and of proline, associated with NO biosynthesis. [ABSTRACT FROM AUTHOR]

Amino acid permeases (AAPs) are involved in transporting a broad spectrum of amino acids and regulating physiological processes in plants. In this study, 19 AAP genes were identified from the tea plants genome database and named CsAAP1–19. Based on phylogenetic analysis, the CsAAP genes were classified into three groups, having significantly different structures and conserved motifs. In addition, an expression analysis revealed that most of CsAAP genes were specifically expressed in different tissues, especially CsAAP19 was expressed only in root. These genes also were significantly expressed in the Baiye 1 and Huangjinya cultivars. Nitrogen treatments indicated that the CsAAP s were obviously expressed in root. CsAAP2 , − 6 , − 12 , − 13 and − 16 were significantly expressed at 6 d after the glutamate treatment, while the expression trend at 24 h after contained the ammonium. These results improve our understanding of the CsAAP genes and their functions in nitrogen utilization in tea plants. [ABSTRACT FROM AUTHOR]

SQUAMOSA promoter-binding protein (SBP)-box gene family is one kind of plant-specific transcription factor that plays important roles in the process of resisting abiotic stress. The SBP-box gene family has been studied in many species, but their functions are not yet clear in Camellia sinensis var. sinensis (CSS) (tea) plants. In our study, 25 SBP-box genes in the CSS were identified in the reference genome and classified into six groups based on a phylogenetic tree. The expression pattern of CsSBP genes under temperature stresses showed that CsSBPs were involved in the process of resisting temperature stresses. CsSBP8 had a positive effect on the anthocyanin accumulation during high temperature exposures, but CsSBP12 has a high correlation with anthocyanin accumulation during both high and low temperature. This study provides a foundation for the further study of CsSBP genes involved in the anthocyanin biosynthesis pathway during the temperature stress in tea. • 25 SBP-box genes were identified in Camellia sinensis var. sinensis (CSS) genome. • Thirteen CsSBPs genes were targets of miR156. • CsSBPs were more sensitive to low temperature stress. • CsSBP8 and CsSBP12 possibly regulate the anthocyanin biosynthesis pathway. [ABSTRACT FROM AUTHOR]

To determine the mechanisms in tea plants responding to temperature stresses (heat and cold), we examined the global transcriptomic and metabolomic profiles of the tea plant cultivar 'Suchazao' under moderately low temperature stress (ML), severely low temperature stress (SL), moderately high temperature stress (MH) and severely high temperature stress (SH) using RNA-seq and high performance liquid chromatography tandem mass spectrometry/mass spectrometry (HPLC-MS/MS), respectively. The identified differentially expressed genes indicated that the synthesis of stress-resistance protein might be redirected to cope with the temperature stresses. We found that heat shock protein genes Hsp90 and Hsp70 played more critical roles in tea plants in adapting to thermal stress than cold, while late embryogenesis abundant protein genes (LEA) played a greater role under cold than heat stress, more types of zinc finger genes were induced under cold stress as well. In addition, energy metabolisms were inhibited by SH, SL and ML. Furthermore, the mechanisms of anthocyanin synthesis were different under the cold and heat stresses. Indeed, the CsUGT75C1 gene, encoding UDP-glucose:anthocyanin 5-O-glucosyl transferase, was up-regulated in the SL-treated leaves but down-regulated in SH. Metabolomics analysis also showed that anthocyanin monomer levels increased under SL. These results indicate that the tea plants share certain foundational mechanisms to adjust to both cold and heat stresses. They also developed some specific mechanisms for surviving the cold or heat stresses. Our study provides effective information about the different mechanisms tea plants employ in surviving cold and heat stresses, as well as the different mechanisms of anthocyanin synthesis, which could speed up the genetic breeding of heat- and cold-tolerant tea varieties. [ABSTRACT FROM AUTHOR]

Key message: Overexpression of grapevine VvABF2 gene could enhance osmotic stress tolerance in Arabidopsis thaliana but fully required for ABA signaling. The abscisic acid (ABA)-dependent AREB/ABF-SnRK2 pathway has been demonstrated to play a pivotal role in response to osmotic stress in model plants. However, its function in other specific species, for example grapevine, has not been fully characterized. In this study, grapevine (Vitis vinifera L.) ABSCISIC ACID RESPONSE ELEMENT-BINDING FACTOR2 (VvABF2), a homologous gene of AREB/ABFs form Arabidopsis, was isolated and constitutively expressed in Arabidopsis under the control of the cauliflower mosaic virus 35S promoter. The VvABF2 transgenic Arabidopsis plants showed to be more sensitive to exogenous ABA compared to wild type plants and exhibited significant osmotic tolerance, like polyethylene glycol (PEG) and drought but fully required ABA for signaling. This fact was further confirmed by its downstream gene expression assays. In addition, the determination of ROS antioxidant enzymes (including SOD, POD and CAT) and the MDA of transgenic lines indicated that overexpression of VvABF2 in Arabidopsis significantly increased ROS scavenging ability and thereby reduced the cell membrane damage, which might be ABA-independent. Our results provide evidence that VvABF2 has a similar function to the Arabidopsis homolog in response to osmotic stresses, and that there is a similar ancestral function of this gene in ABA-dependent response to stresses in grapevine. [ABSTRACT FROM AUTHOR]

• latex particle-enhanced turbidimetric immunoassay based on cyclic citrullinated peptide-immobilized latex bead was proposed for fast measurements of anti-citrillinated protein antibody of rheumatoid arthritis patients • Cyclic citrullinated peptide-immobilized latex bead was fabricated through three methods, including direct coupling, overall coupling and layer by layer coupling. • Compared with ELISA, latex particle-enhanced turbidimetric immunoassay for detection of anti-citrillinated protein antibody of rheumatoid arthritis patients based on the homemade Kit is more easy, cheap and rapid. The anti-citrillinated protein antibody (ACPA) plays an important role in early diagnosis of rheumatoid arthritis (RA), and is usually detected by using cyclic citrullinated peptide (CCP) as antigen. The ACPA against CCP test is usually performed utilizing enzyme-linked immunosorbent assay (ELISA), but the ELISA is expensive and time-consuming. Here, latex particle-enhanced turbidimetric immunoassay (LTIA) based on CCP-immobilized latex bead was proposed for fast measurements of ACPA of RA patients. CCP-immobilized latex bead was fabricated through three methods, including direct coupling, overall coupling and layer by layer coupling. According to the optimized experiments, layer-by-layer coupling was the best method with advantages of time-saving, simple operation and good repeatability. In addition, a spacer arm of appropriate length between latex beads and CCP could avoid stereoscopic obstacles and make ACPA closer to CCP. The CCP-immobilized latex bead based on layer by layer coupling (CCP-LB-LLC) was used for assembling the homemade kit, which was applied in fast measurements of ACPA through LTIA. The homemade kit possessed a low limit of detection (0.2 U/mL) and an acceptable the batch-to-batch reproducibility. In addition, the homemade kit can be stored at 4 °C for at least one month. When used to detect 20 clinical samples, the results of homemade kit were consistent with commercial ELISA. Furthermore, LTIA based on the homemade kit was simpler and cheaper than ELISA. These results demonstrated that the homemade kit could be useful for diagnosis of RA patients. [ABSTRACT FROM AUTHOR]

JAZ (Jasmonate ZIM-domain) proteins play pervasive roles in plant development and defense reaction. However, limited information is known about the JAZ family in Camellia sinensis. In this study, 12 non-redundant JAZ genes were identified from the tea plant genome database. Phylogenetic analysis showed that the 12 JAZ proteins belong to three groups. The cis-elements in promoters of CsJAZ genes and CsJAZ proteins interaction networks were also analyzed. Quantitative RT–PCR analysis showed that 7 CsJAZ genes were preferentially expressed in roots. Furthermore, the CsJAZ expressions were differentially induced by cold, heat, polyethylene glycol (PEG), methyl jasmonate (MeJA), and gibberellin (GA) stimuli. The Pearson correlations analysis based on expression levels showed that the CsJAZ gene pairs were differentially expressed under different stresses, indicating that CsJAZs might exhibit synergistic effects in response to various stresses. Subcellular localization assay demonstrated that CsJAZ3, CsJAZ10, and CsJAZ11 fused proteins were localized in the cell nucleus. Additionally, the overexpression of CsJAZ3, CsJAZ10, and CsJAZ11 in E. coli enhanced the growth of recombinant cells under abiotic stresses. In summary, this study will facilitate the understanding of the CsJAZ family in Camellia sinensis and provide new insights into the molecular mechanism of tea plant response to abiotic stresses and hormonal stimuli. [ABSTRACT FROM AUTHOR]

To understand the effects of geographic locations, cultivation altitude, slope, and aspect on secondary metabolites in tea leaves, 78 tea samples were randomly collected from Southern Jiangsu region, China, and catechins, caffeine, and free amino acids were examined. The results showed that samples from the farther north had higher contents of TC, EGCG + GCG, ECG + CG and the ratios of ETC to NTC, while had lower contents of free amino acids, leading to more bitterness and astringency taste in tea. Furthermore, more free amino acids were accumulated in tea cultivated in hilly areas due to shorter sun exposure time and lower intensity than plain areas with the rotation of the earth formed a natural shade management effect, whereas more TC in plain areas. Principal Component Analysis (PCA) grouped the 78 tea samples into three clusters and further confirmed that tea samples from a similar geographical environment exhibited a similar constituent of major secondary metabolites. These results might be useful for providing references to regional tea plantation planning, tea plantations location selection and geographical environment management. • Catechins and free amino acids contents in tea are affected by cultivation location. • Tea cultivated in hilly areas gets more free amino acid due to topographic shading. • Tea cultivated in plain areas gets more TC due to longer sun exposure time. • Tea cultivated in similar geographical environment gets similar secondary metabolites. [ABSTRACT FROM AUTHOR]

Background: Internal γ-Aminobutyric Acid (GABA) interacting with stress response substances may be involved in the regulation of differentially abundant proteins (DAPs) associated with optimum temperature and cold stress in tea plants (Camellia sinensis (L.) O. Kuntze). Results: Tea plants supplied with or without 5.0 mM GABA were subjected to optimum or cold temperatures in this study. The increased GABA level induced by exogenous GABA altered levels of stress response substances – such as glutamate, polyamines and anthocyanins – in association with improved cold tolerance. Isobaric tags for relative and absolute quantification (iTRAQ) – based DAPs were found for protein metabolism and nucleotide metabolism, energy, amino acid transport and metabolism other biological processes, inorganic ion transport and metabolism, lipid metabolism, carbohydrate transport and metabolism, biosynthesis of secondary metabolites, antioxidant and stress defense. Conclusions: The iTRAQ analysis could explain the GABA-induced physiological effects associated with cold tolerance in tea plants. Analysis of functional protein–protein networks further showed that alteration of endogenous GABA and stress response substances induced interactions among photosynthesis, amino acid biosynthesis, and carbon and nitrogen metabolism, and the corresponding differences could contribute to improved cold tolerance of tea plants. [ABSTRACT FROM AUTHOR]

Tea (Camellia sinensis (L.) O. Kuntze), one of the main crops in China, is high in various bioactive compounds including flavonoids, catechins, caffeine, theanine, and other amino acids. C. sinensis is also known as an accumulator of fluoride (F), and the bioactive compounds are affected by F, however, the mechanism remains unclear. Here, the effects of F treatment on the accumulation of F and major bioactive compounds and gene expression were investigated, revealing the molecular mechanisms affecting the accumulation of bioactive compounds by F treatment. The results showed that F accumulation in tea leaves gradually increased under exogenous F treatments. Similarly, the flavonoid content also increased in the F treatment. In contrast, the polyphenol content, free amino acids, and the total catechins decreased significantly. Special amino acids, such as sulfur-containing amino acids and proline, had the opposite trend of free amino acids. Caffeine was obviously induced by exogenous F, while the theanine content peaked after two day-treatment. These results suggest that the F accumulation and content of bioactive compounds were dramatically affected by F treatment. Furthermore, differentially expressed genes (DEGs) related to the metabolism of main bioactive compounds and amino acids, especially the pivotal regulatory genes of catechins, caffeine, and theanine biosynthesis pathways, were identified and analyzed using high-throughput Illumina RNA-Seq technology and qRT-PCR. The expression of pivotal regulatory genes is consistent with the changes of the main bioactive compounds in C. sinensis leaves, indicating a complicated molecular mechanism for the above findings. Overall, these data provide a reference for exploring the possible molecular mechanism of the accumulation of major bioactive components such as flavonoid, catechins, caffeine, theanine and other amino acids in tea leaves in response to fluoride treatment. [ABSTRACT FROM AUTHOR]