Kang Sun

Meta-Analysis of the Association between Tea Intake and the Risk of Cognitive Disorders.

Background Alzheimer’s disease is a common neurodegenerative disorder in elderly. This study was aimed to systematically evaluate the association between tea intake and the risk of cognitive disorders by meta-analysis. Methods and Findings PubMed, Embase and Wanfang databases were systematically searched and a total of 26 observational studies were included in this study. Odds ratios (ORs) and the corresponding 95% confidence intervals (CIs) were calculated and pooled by using fixed or random effects models according to the degree of heterogeneity. Results The overall pooled analysis indicated that tea intake could significantly reduce the risk of cognitive disorders (OR = 0.65, 95%CI = 0.58–0.73). Subgroup analyses were conducted based on study design, population, frequency of tea drinking and type of cognitive disorders. The results showed that tea drinking was significantly associated with the reduced incidence of cognitive disorders in all of subgroups based on study design and frequency of tea drinking. In particular, tea drinking was inversely associated with the risk of cognitive impairment (CoI), mild cognitive impairment (MCI), cognitive decline and ungrouped cognitive disorders. Moreover, for population subgroups, the significant association was only found in Chinese people. Conclusion Our study suggests that daily tea drinking is associated with decreased risk of CoI, MCI and cognitive decline in the elderly. However, the association between tea intake and Alzheimer’s disease remains elusive.

The CsHSP17.2 molecular chaperone is essential for thermotolerance in Camellia sinensis

Small heat shock proteins (sHSPs) play important roles in responses to heat stress. However, the functions of sHSPs in tea plants (Camellia sinensis) remain uncharacterized. A novel sHSP gene, designated CsHSP17.2, was isolated from tea plants. Subcellular localization analyses indicated that the CsHSP17.2 protein was present in the cytosol and the nucleus. CsHSP17.2 expression was significantly up-regulated by heat stress but was unaffected by low temperature. The CsHSP17.2 transcript levels increased following salt and polyethylene glycol 6000 treatments but decreased in the presence of abscisic acid. The molecular chaperone activity of CsHSP17.2 was demonstrated in vitro. Transgenic Escherichia coli and Pichia pastoris expressing CsHSP17.2 exhibited enhanced thermotolerance. The transgenic Arabidopsis thaliana exhibited higher maximum photochemical efficiencies, greater soluble protein proline contents, higher germination rates and higher hypocotyl elongation length than the wild-type controls. The expression levels of several HS-responsive genes increased in transgenic A. thaliana plants. Additionally, the CsHSP17.2 promoter is highly responsive to high-temperature stress in A. thaliana. Our results suggest that CsHSP17.2 may act as a molecular chaperone to mediate heat tolerance by maintaining maximum photochemical efficiency and protein synthesis, enhancing the scavenging of reactive oxygen species and inducing the expression of HS-responsive genes.

Molecular Link between Leaf Coloration and Gene Expression of Flavonoid and Carotenoid Biosynthesis in Camellia sinensis Cultivar ‘Huangjinya’

‘Huangjinya’ is an excellent albino tea germplasm cultivated in China because of its bright color and high amino acid content. It is light sensitive, with yellow leaves under intense light while green leaves under weak light. As well, the flavonoid and carotenoid levels increased after moderate shading treatment. However, the mechanism underlying this interesting phenomenon remains unclear. In this study, the transcriptome of ‘Huangjinya’ plants exposed to sunlight and shade were analyzed by high-throughput sequencing followed by de novo assembly. Shading ‘Huangjinya’ made its leaf color turn green. De novo assembly showed that the transcriptome of ‘Huangjinya’ leaves comprises of 127,253 unigenes, with an average length of 914 nt. Among the 81,128 functionally annotated unigenes, 207 differentially expressed genes were identified, including 110 up-regulated and 97 down-regulated genes under moderate shading compared to full light. Gene ontology (GO) indicated that the differentially expressed genes are mainly involved in protein and ion binding and oxidoreductase activity. Antioxidation-related pathways, including flavonoid and carotenoid biosynthesis, were highly enriched in these functions. Shading inhibited the expression of flavonoid biosynthesis-associated genes and induced carotenoid biosynthesis-related genes. This would suggest that decreased flavonoid biosynthetic gene expression coincides with increased flavonoids (e.g., catechin) content upon moderate shading, while carotenoid levels and biosynthetic gene expression are positively correlated in ‘Huangjinya.’ In conclusion, the leaf color changes in ‘Huangjinya’ are largely determined by the combined effects of flavonoid and carotenoid biosynthesis.

Involvement of CsCDPK20 and CsCDPK26 in Regulation of Thermotolerance in Tea Plant (Camellia sinensis)

Calcium-dependent protein kinases (CDPKs) play critical roles in the regulation of plant growth, development, and stress response. In this study, Camellia sinensis CsCDPK1, CsCDPK3, CsCDPK20, and CsCDPK26 were cloned and functionally characterized. Bioinformatics analyses showed that all analyzed CsCDPK genes encoded the expected CDPK structures. Subcellular localization indicated that the four CsCDPK proteins were localized to the cytoplasm and nucleus in onion epidermal cells. The quantitative real-time PCR results indicated that the four CsCDPK genes exhibited tissue-specific expression patterns. Exposure to heat stress and exogenous abscisic acid induced increases in CsCDPK20 and CsCDPK26 transcript abundance at different time points. Furthermore, overexpression of CsCDPK20 and CsCDPK26 increased the thermotolerance in transgenic Arabidopsis thaliana plants. The proline content in leaves was significantly higher in transgenic plants than that in wild-type under heat stress, whereas malondialdehyde content was lower in transgenic plants. Additionally, expression of stress-responsive genes (i.e., AtAPX1, AtPOD, AtProT1, AtP5CS2, AtHSFA2, AtHSP70, AtHSP101, AtRD29B, AtRAB18, AtABI1, AtRBOHD, and AtRBOHF) was increased in the CsCDPK20 and CsCDPK26 transgenic A. thaliana plants compared with that in the wild type. Collectively, our results suggest that CsCDPK20 and CsCDPK26 may act as positive regulator in C. sinensis response to heat stress.

Transcriptomic analyses identify albino-associated genes of a novel albino tea germplasm ‘Huabai 1’

Albinism in shoots of tea plants is a common phenotypic expression which gives the tea infusion a pleasant umami taste. A novel natural albino mutant tea germplasm containing high amino acids content was found and named as ‘Huabai 1’. ‘Huabai 1’ has white jade tender shoots under low temperature and turns green with increased temperature. In order to understand the molecular mechanism of color change in leaf of ‘Huabai 1’, transcriptome analysis was performed to identify albino-associated differentially expressed genes (DEGs). A total of 483 DEGs were identified from white shoots of ‘Huabai 1’ compared to its green shoots. There were 15 DEGs identified to be involved in phenylpropanoid biosynthesis, which account for the majority of characterized DEGs. The metabolites related to phenylpropanoid biosynthesis revealed similar expression pattern of DEGs. Furthermore, metabolic pathways such as ubiquonone, tyrosine, and flavonoid biosynthesis associated with phenylpropanoid biosynthesis could also contribute to the color change in ‘Huabai 1’ tender shoots. Protein–protein interaction analysis revealed a hub protein NEDD8 (CSA009575) which interacted with many regulated genes in spliceosome, nitrogen metabolism, phenylpropanoid biosynthesis, and other pathways. In conclusion, the findings in this study indicate that the color change of ‘Huabai 1’ tender shoots is a combined effect of phenylpropanoid biosynthesis pathway and other metabolic pathways including flavonoid biosynthesis in tea plants. Chlorophyll biosynthesis-related genes LHCII and SGR may also play some roles in color change of ‘Huabai 1’.Tea plants: Controlling color and flavorResearchers have identified genes and related metabolic processes in tea plants that control the lack of green color known as albinism, which gives the tea a savory “umami” taste. The scientists, led by Xinghui Li at Nanjing Agricultural University in China, investigated genes associated with color changes in tender shoots of a novel albino variety of tea plant known as Huabai 1. The transition from white to green shoots is a temperature-dependent process associated with differences in the activity of 483 identified genes. Control of the color change is also linked to alterations in chemical reaction pathways involving a variety of plant compounds, including phenylpropanoids, flavonoids and the green chlorophylls most commonly associated with plant color. The insights may help plant breeders to create new varieties of teas with highly prized desirable flavors

Transcriptomic analysis between self- and cross-pollinated pistils of tea plants ( Camellia sinensis )

BackgroundSelf-incompatibility (SI) is a major barrier that obstructs the breeding process in most horticultural plants including tea plants (Camellia sinensis). The aim of this study was to elucidate the molecular mechanism of SI in tea plants through a high throughput transcriptome analysis.ResultsIn this study, the transcriptomes of self- and cross-pollinated pistils of two tea cultivars ‘Fudingdabai’ and ‘Yulv’ were compared to elucidate the SI mechanism of tea plants. In addition, the ion components and pollen tube growth in self- and cross-pollinated pistils were investigated. Our results revealed that both cultivars had similar pollen activities and cross-pollination could promote the pollen tube growth. In tea pistils, the highest ion content was potassium (K+), followed by calcium (Ca2+), magnesium (Mg2+) and phosphorus (P5+). Ca2+ content increased after self-pollination but decreased after cross-pollination, while K+ showed reverse trend with Ca2+. A total of 990 and 3 common differentially expressed genes (DEGs) were identified in un-pollinated vs. pollinated pistils and self- vs. cross-pollinated groups after 48xa0h, respectively. Function annotation indicated that three genes encoding UDP-glycosyltransferase 74B1 (UGT74B1), Mitochondrial calcium uniporter protein 2 (MCU2) and G-type lectin S-receptor-like serine/threonine-protein kinase (G-type RLK) might play important roles during SI process in tea plants.ConclusionCa2+ and K+ are important signal for SI in tea plants, and three genes including UGT74B1, MCU2 and G-type RLK play essential roles during SI signal transduction.

Dietary Copper Reduces the Hepatotoxicity of (−)-Epigallocatechin-3-Gallate in Mice

We developed Cu-deficient, -sufficient and -super nutrition mice models by feeding them with diet containing 1.68, 11.72 or 51.69 mg of Cu/kg for 28 days, respectively. Then, the mice were treated to (−)-epigallocatechin-3-gallate (EGCG, 750 mg/kg BW) by oral in order to assess the acute toxicity of the drug. Following EGCG treatment, the survival rates were 12.5%, 50% and 100% in the Cu-deficient, -sufficient and Cu-super nutrition groups of mice, respectively. Cu level and ceruloplasmin activity in serum were significantly increased with the increase of dietary Cu. However, the Cu supplementation did not produce any obvious impact on serum superoxide dismutase activity. Furthermore, ceruloplasmin, in vitro, significantly promotes EGCG oxidation accompanied with increasing oxidation products and decreasing levels of reactive oxygen species. These results, therefore, suggest that Cu can relieve EGCG hepatotoxicity, possibly by up-regulating ceruloplasmin activity, which can be used to promote EGCG applications.

Association between tea consumption and osteoporosis: A meta-analysis

Background: Previous reports have suggested a potential association of tea consumption with the risk of osteoporosis. As such association is controversial, we conducted a meta-analysis to assess the relationship between tea consumption and osteoporosis. Methods and Findings: We systematically searched PubMed, EMBASE and WanFang databases until March 30, 2016, using the keywords “tea and osteoporosis,” without limits of language. Odds ratios (ORs) with 95% confidence intervals (95% CIs) were derived by using random-effects models throughout the analyses. We conducted the analysis of the statistical heterogeneity using Cochrane I2. The funnel plot was used to speculate the publication bias, while the subgroup analysis and multiround elimination method were employed. Results: Our study was based on 17 journal articles, including 2 prospective cohort studies, 4 case–control studies, and 11 cross-sectional studies. In the present study, the total OR of osteoporosis for the highest versus the lowest categories of tea consumption was 0.62 (95% CI, 0.46–0.83), with significant heterogeneity among studies (I2u200a=u200a94%, Pu200a<u200a.01). There was, however, no publication bias of the meta-analysis about tea consumption and osteoporosis. Subgroup analysis showed that tea consumption could reduce the risk of osteoporosis in all examined subgroups. Conclusion: In the present study, it can be concluded from the results that tea consumption can reduce the risk of osteoporosis.

Colletotrichum gloeosporioides contaminated tea infusion blocks lipids reduction and induces kidney damage in mice

When the homogenate of fresh tea tree leaves was fermented to produce black tea beverage, the Colletotrichum gloeosporioides (main pathogen or endophyte of Camellia sinensis) may be mixed into the fermentation liquor. However, it was unclear whether C. gloeosporioides-contaminated tea beverage would damage human health. Therefore, we investigated the changes of functional components and the influences on mice. C. gloeosporioides was added to the green tea infusion. After cultivation of 48 h, tea polyphenols, caffeine, and L-theanine decreased by 31.0, 26.2, and 8.3%, respectively. The contaminated tea infusion showed brown stain, and produced a group of toxic materials named phthalic acid esters. The animal study showed that green tea without contamination significantly decreased levels of alanine aminotransferase, triglycerides, free fatty acids, low-density lipoprotein, and increased insulin level compared with obese mice. On the contrary, contaminated tea lost the effects on these indicators. Furthermore, the urea nitrogen and serum creatinine levels significantly increased in the contaminated tea-drinking mice. Altogether, our results indicate that C. gloeosporioides contamination can reduce the amount of functional components of green tea. Therefore, it inhibits some health-care function of lipid-lowering. In addition, the toxic components in contaminated tea infusion might induce renal damage.