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1.
Food Chem ; 305: 125440, 2020 Feb 01.
Artigo em Inglês | MEDLINE | ID: mdl-31494496

RESUMO

Tea (Camellia sinensis) contains two active glutamate decarboxylases (CsGADs), whose unclear properties were examined here. CsGAD1 was 4-fold higher than CsGAD2 in activity. Their Km values for L-glutamate were around 5 mM. CsGAD1 and CsGAD2 performed best at 55 and 40 °C, respectively, and were both stimulated by calcium/calmodulin (Ca2+/CaM). Over 40 °C, their calmodulin-binding domains degraded. CsGADs were most active at pH 5.6, and were stimulated by Ca2+/CaM at pH 5.6-6.6, but inactivated at pH 3.6. Ca2+/CaM restored the CsGAD1 activity suppressed by inhibitors. CsGADs and CsCaM were localized to the cytosol. CsGAD1 was more highly expressed in most tissues, while CsGAD2 expression was more induced under stresses. The characteristics we first elucidated here revealed that CsGAD1 is the predominant isoform in tea plant, with CsGAD2 exhibiting a supplementary role under certain conditions. The information will contribute to regulation of GABA tea quality.

2.
Biomolecules ; 9(12)2019 Nov 30.
Artigo em Inglês | MEDLINE | ID: mdl-31801241

RESUMO

When insects attack plants, insect-derived elicitors and mechanical damage induce the formation and emission of plant volatiles that have important ecological functions and flavor properties. These events have mainly been studied in model plants, rather than crop plants. Our study showed that tea green leafhopper (Empoasca (Matsumurasca) onukii Matsuda), a major pest infesting tea attack significantly induced the emission of geraniol from tea leaves, but did not affect the crude enzyme activity of geraniol synthase in tea leaves. An enzyme extract of E. (M.) onukii specifically produced geraniol from geraniol diphosphate. Furthermore, a terpene synthase (EoTPS) was isolated from E. (M.) onukii. This terpene synthase was able to convert geraniol diphosphate to geraniol in vitro. In addition, geraniol had in vitro ability to inhibit the growth of Acinetobacter johnsonii that is endobacterial isolated from E. (M.) onukii. This information illustrates that elicitors from piercing-sucking insects can induce the formation of volatiles from crop plants and advances our understanding of the roles of plant volatiles in the interaction among crops-insects-microorganisms.

3.
Plant Sci ; 287: 110179, 2019 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-31481215

RESUMO

Stigmatic mucilage plays a crucial role in pollen-grain adhesion on the stigma in flowering plants. Little information is available regarding mucilage biosynthesis in orchid plants. In the present study, stigmatic mucilage is rich in galactose-containing polysaccharides, mainly consisted of galactose and arabinose in Dendrobium officinale. Thirteen galactosyltransferases involved in biosynthesis of the ß-1,3-galactose linkage polysaccharides, belonging to the CAZY GT31 family, were identified from D. officinale genome. A positive correlation between the mucilage content and the DoGALT2 expression at different stages was observed. DoGALT2 expressed overall sampled tissues with the highest in D. officinale stigmatic mucilage that contributes to pollen adhesion and elongation. DoGALT2 was targeted to Golgi, and had a GALT domain (PF01762) that was homologous to the characterized GALT2 in Arabidopsis. Compared to wild-type Arabidopsis, DoGALT2 overexpressing plants showed a higher content of galactose and galactose-containing alcohol-insoluble residues, and enhanced tolerance to abiotic stress. DoGALT2 complemented Arabidopsis GALT2 mutant (galt2-1), with an equivalent galactose with wild-type Arabidopsis but significantly higher than galt2-1. These findings provide evidence that DoGALT2 might be involved in regulating the biosynthesis of galactose-containing polysaccharides during D. officinale pollen development.

4.
Mol Plant ; 12(11): 1485-1498, 2019 Nov 04.
Artigo em Inglês | MEDLINE | ID: mdl-31382023

RESUMO

Plants maintain a dynamic balance between growth and defense , and optimize allocation of resources for survival under constant pathogen infections. However, the underlying molecular regulatory mechanisms, especially in response to biotrophic bacterial infection, remain elusive. Here, we demonstrate that DELLA proteins and EDS1, an essential resistance regulator, form a central module modulating plant growth-defense tradeoffs via direct interaction. When infected by Pst DC3000, EDS1 rapidly promotes salicylic acid (SA) biosynthesis and resistance-related gene expression to prime defense response, while pathogen infection stabilizes DELLA proteins RGA and RGL3 to restrict growth in a partially EDS1-dependent manner, which facilitates plants to develop resistance to pathogens. However, the increasingly accumulated DELLAs interact with EDS1 to suppress SA overproduction and excessive resistance response. Taken together, our findings reveal a DELLA-EDS1-mediated feedback regulatory loop by which plants maintain the subtle balance between growth and defense to avoid excessive growth or defense in response to constant biotrophic pathogen attack.

5.
Int J Mol Sci ; 20(17)2019 Aug 25.
Artigo em Inglês | MEDLINE | ID: mdl-31450700

RESUMO

Herbivore-induced plant volatiles (HIPVs) play important ecological roles in defense against stresses. In contrast to model plants, reports on HIPV formation and function in crops are limited. Tea (Camellia sinensis) is an important crop in China. α-Farnesene is a common HIPV produced in tea plants in response to different herbivore attacks. In this study, a C. sinensis α-farnesene synthase (CsAFS) was isolated, cloned, sequenced, and functionally characterized. The CsAFS recombinant protein produced in Escherichia coli was able to transform farnesyl diphosphate (FPP) into α-farnesene and also convert geranyl diphosphate (GPP) to ß-ocimene in vitro. Furthermore, transient expression analysis in Nicotiana benthamiana plants indicated that CsAFS was located in the cytoplasm and could convert FPP to α-farnesene in plants. Wounding, to simulate herbivore damage, activated jasmonic acid (JA) formation, which significantly enhanced the CsAFS expression level and α-farnesene content. This suggested that herbivore-derived wounding induced α-farnesene formation in tea leaves. Furthermore, the emitted α-farnesene might act as a signal to activate antibacterial-related factors in neighboring undamaged tea leaves. This research advances our understanding of the formation and signaling roles of common HIPVs in crops such as tea plants.

6.
J Agric Food Chem ; 67(36): 10145-10154, 2019 Sep 11.
Artigo em Inglês | MEDLINE | ID: mdl-31418564

RESUMO

2-Phenylethanol (2PE) is a representative aromatic aroma compound in tea (Camellia sinensis) leaves. However, its formation in tea remains unexplored. In our study, feeding experiments of [2H8]L-phenylalanine (Phe), [2H5]phenylpyruvic acid (PPA), or (E/Z)-phenylacetaldoxime (PAOx) showed that three biosynthesis pathways for 2PE derived from L-Phe occurred in tea leaves, namely, pathway I (via phenylacetaldehyde (PAld)), pathway II (via PPA and PAld), and pathway III (via (E/Z)-PAOx and PAld). Furthermore, increasing temperature resulted in increased flux into the pathway for 2PE from L-Phe via PPA and PAld. In addition, tomato fruits and petunia flowers also contained the 2PE biosynthetic pathway from L-Phe via PPA and PAld and increasing temperatures led to increased flux into this pathway, suggesting that such a phenomenon might be common among most plants containing 2PE. This represents a characteristic example of changes in flux into the biosynthesis pathways of volatile compounds in plants in response to stresses.


Assuntos
Camellia sinensis/metabolismo , Lycopersicon esculentum/química , Petunia/química , Álcool Feniletílico/metabolismo , Vias Biossintéticas , Flores/química , Frutas/química , Folhas de Planta/metabolismo , Temperatura Ambiente
7.
Food Chem ; 292: 204-210, 2019 Sep 15.
Artigo em Inglês | MEDLINE | ID: mdl-31054666

RESUMO

Although specialized metabolite distributions in different tea (Camellia sinensis) tissues has been studied extensively, little is known about their within-tissue distribution owing to the lack of nondestructive methodology. In this study, desorption electrospray ionization imaging mass spectrometry was used to investigate the within-tissue spatial distributions of specialized metabolites in tea. To overcome the negative effects of the large amount of wax on tea leaves, several sample preparation methods were compared, with a Teflon-imprint method established for tea leaves. Polyphenols are characteristic metabolites in tea leaves. Epicatechin gallate/catechin gallate, epigallocatechin gallate/gallocatechin gallate, and gallic acid were evenly distributed on both sides of the leaves, while epicatechin/catechin, epigallocatechin/gallocatechin, and assamicain A were distributed near the leaf vein. L-Theanine was mainly accumulated in tea roots. L-Theanine and valinol were distributed around the outer root cross-section. The results will advance our understanding of the precise localizations and in-vivo biosyntheses of specialized metabolites in tea.


Assuntos
Camellia sinensis/metabolismo , Polifenóis/análise , Espectrometria de Massas por Ionização por Electrospray/métodos , Camellia sinensis/química , Catequina/análogos & derivados , Catequina/análise , Ácido Gálico/análise , Glutamatos/análise , Folhas de Planta/química , Folhas de Planta/metabolismo , Raízes de Plantas/química , Raízes de Plantas/metabolismo
8.
J Agric Food Chem ; 67(23): 6541-6550, 2019 Jun 12.
Artigo em Inglês | MEDLINE | ID: mdl-31125230

RESUMO

The enzymatic hydrolysis of glycosidically bound volatiles (GBVs) plays an important role in tea aroma formation during the tea manufacturing process. However, during the enzyme-active manufacturing process of oolong tea, most GBVs showed no reduction, while ( Z)-3-hexenyl-ß-glucopyranoside significantly enhanced at the turnover stage. This study aimed to determine the reason for this increase in ( Z)-3-hexenyl-ß-glucopyranoside. Continuous wounding stress in the turnover stage did not enhance the expression level of glycosyltransferase 1 ( CsGT1), while it induced a significant increase in the ( Z)-3-hexenol content ( p ≤ 0.05). Furthermore, observing the cell structures of tea leaves exposed to continuous wounding and subcellular localizations of CsGTs suggested that the interaction of ( Z)-3-hexenol (substrate) and CsGT1 (enzyme) was available. In conclusion, both continuous wounding and subcellular localizations led to a ( Z)-3-hexenyl-ß-glucopyranoside enhancement mechanism during the oolong tea's turnover stage. These results advance our understanding of GBV formation during the tea manufacturing process and their relationship with the stress from the tea manufacturing process. In addition, the information will help us further evaluate contribution of GBVs to enzymatic formation of oolong tea aroma compounds.


Assuntos
Camellia sinensis/química , Manipulação de Alimentos/métodos , Glucosídeos/análise , Camellia sinensis/enzimologia , Camellia sinensis/genética , Camellia sinensis/fisiologia , Glicosiltransferases/genética , Glicosiltransferases/metabolismo , Folhas de Planta/química , Folhas de Planta/fisiologia , Proteínas de Plantas/genética , Proteínas de Plantas/metabolismo , Estresse Fisiológico , Compostos Orgânicos Voláteis/análise
9.
J Agric Food Chem ; 67(24): 6716-6724, 2019 Jun 19.
Artigo em Inglês | MEDLINE | ID: mdl-31135151

RESUMO

Insect attack is known to induce a high accumulation of volatile metabolites in tea ( Camellia sinensis). However, little information is available concerning the effect of insect attack on tea quality-related nonvolatile specialized metabolites. This study aimed to investigate the formation of characteristic nonvolatile specialized metabolites in tea leaves in response to attack by major tea insects, namely, tea green leafhoppers and tea geometrids, and determine the possible involvement of phytohormones in metabolite formation resulting from insect attack. Both tea green leafhopper and tea geometrid attacks increased the jasmonic acid and salicylic acid contents. The abscisic acid content was only increased under tea green leafhopper attack, perhaps due to special continuous piercing-sucking wounding. Tea green leafhopper attack induced the formation of theaflavins from catechins under the action of polyphenol oxidase, while tea geometrid attack increased the l-theanine content. Exogenous phytohormone treatments can affect the caffeine and catechin contents. These results will help to determine the influence of major tea pest insects on important tea quality-related metabolites and enhance understanding of the relationship of phytohormones and quality-related nonvolatile metabolite formation in tea exposed to tea pest insect attacks.


Assuntos
Camellia sinensis/metabolismo , Hemípteros/fisiologia , Folhas de Planta/química , Folhas de Planta/parasitologia , Animais , Biflavonoides/análise , Biflavonoides/metabolismo , Camellia sinensis/química , Camellia sinensis/parasitologia , Catequina/análise , Catequina/metabolismo , Ciclopentanos/análise , Ciclopentanos/metabolismo , Glutamatos/análise , Glutamatos/metabolismo , Oxilipinas/análise , Oxilipinas/metabolismo , Reguladores de Crescimento de Planta/química , Reguladores de Crescimento de Planta/metabolismo , Folhas de Planta/metabolismo , Ácido Salicílico/análise , Ácido Salicílico/metabolismo
10.
Int J Mol Sci ; 20(5)2019 Feb 27.
Artigo em Inglês | MEDLINE | ID: mdl-30818885

RESUMO

Characteristic aroma formation in tea (Camellia sinensis) leaves during the oolong tea manufacturing process might result from the defense responses of tea leaves against these various stresses, which involves upregulation of the upstream signal phytohormones related to leaf chloroplasts, such as jasmonic acid (JA). Whether chloroplast changes affect the formation of JA and characteristic aroma compounds in tea leaves exposed to stresses is unknown. In tea germplasms, albino-induced yellow tea leaves have defects in chloroplast ultrastructure and composition. Herein, we have compared the differential responses of phytohormone and characteristic aroma compound formation in normal green and albino-induced yellow tea leaves exposed to continuous wounding stress, which is the main stress in oolong tea manufacture. In contrast to single wounding stress (from picking, as a control), continuous wounding stress can upregulate the expression of CsMYC2, a key transcription factor of JA signaling, and activate the synthesis of JA and characteristic aroma compounds in both normal tea leaves (normal chloroplasts) and albino tea leaves (chloroplast defects). Chloroplast defects had no significant effect on the expression levels of CsMYC2 and JA synthesis-related genes in response to continuous wounding stress, but reduced the increase in JA content in response to continuous wounding stress. Furthermore, chloroplast defects reduced the increase in volatile fatty acid derivatives, including jasmine lactone and green leaf volatile contents, in response to continuous wounding stress. Overall, the formation of metabolites derived from fatty acids, such as JA, jasmine lactone, and green leaf volatiles in tea leaves, in response to continuous wounding stress, was affected by chloroplast defects. This information will improve understanding of the relationship of the stress responses of JA and aroma compound formation with chloroplast changes in tea.


Assuntos
Camellia sinensis/química , Cloroplastos/metabolismo , Ciclopentanos/metabolismo , Oxilipinas/metabolismo , Folhas de Planta/química , Folhas de Planta/fisiologia , Estresse Fisiológico , Compostos Orgânicos Voláteis/análise , Camellia sinensis/genética , Regulação da Expressão Gênica de Plantas , Genes de Plantas , Reguladores de Crescimento de Planta/metabolismo
11.
Food Chem ; 283: 131-140, 2019 Jun 15.
Artigo em Inglês | MEDLINE | ID: mdl-30722852

RESUMO

Bananas are a recommended food source to alleviate vitamin A deficiency because they contain a high ratio of provitamin A precursors. The objective of this study was to investigate carotenoid accumulation pattern in banana fruits during postharvest ripening and the mechanisms regulating this process. Ripe banana pulp had an unusually high α-/ß-carotene ratio (1.05), and the carotenoid contents increased (p ≤ 0.05) under light and high temperature. We analyzed the sequences, transcript levels, and functions of genes involved in carotenoid synthesis. The high ratio of α-/ß-carotene in ripe banana fruit was explained by the high flux to the α-carotene biosynthetic pathway, as reflected by high transcript levels of LCYE, and the weak flux to the ß-carotene branch of the biosynthetic pathway due to inactive MaLCYB1.2. High temperature during ripening up-regulated the transcript levels of genes involved in the α- and ß-carotene biosynthesis pathways and the activities of their encoded enzymes.


Assuntos
Carotenoides/análise , Liases Intramoleculares/metabolismo , Musa/química , beta Caroteno/análise , Carotenoides/metabolismo , Cromatografia Líquida de Alta Pressão , Frutas/metabolismo , Liases Intramoleculares/genética , Luz , Musa/metabolismo , RNA de Plantas/química , RNA de Plantas/isolamento & purificação , RNA de Plantas/metabolismo , Análise de Sequência de RNA , Temperatura Ambiente , beta Caroteno/metabolismo
12.
Food Chem ; 280: 27-33, 2019 May 15.
Artigo em Inglês | MEDLINE | ID: mdl-30642496

RESUMO

1-Phenylethanol is a chiral flavor compound that has enantiomers, (R)- and (S)-1-phenylethanol, with different flavor properties. Given that isolating these enantiomers from plants is low yielding and costly, enzymatic synthesis presents an alternative approach. However, the genes/enzymes that specifically produce (R)- and (S)-1-phenylethanol in plants are unknown. To identify these enzymes in tea (Camellia sinensis) flowers, 21 short chain dehydrogenase (SDR) genes were isolated from tea flowers, cloned, and functionally characterized. Several recombinant SDRs in Escherichia coli exhibited activity for converting acetophenone to (S)-1-phenylethanol (CsSPESs, >99.0%), while only one SDR produced (R)-1-phenylethanol (CsRPES, 98.6%). A pair of homologue enzymes (CsSPES and CsRPES) showed a strong preference for NADPH cofactor, with optimal enzymatic reaction conditions of 45-55 °C and pH 8.0. Identification of the tea flower-derived gene responsible for specific synthesis of (R)- and (S)-1-phenylethanolsuggests enzymatic synthesis of enantiopure 1-phenylethanol is possible using a plant-derived gene.


Assuntos
Camellia sinensis/química , Oxirredutases/metabolismo , Álcool Feniletílico/química , Proteínas de Plantas/metabolismo , Camellia sinensis/enzimologia , Camellia sinensis/metabolismo , Aromatizantes/química , Flores/enzimologia , Cromatografia Gasosa-Espectrometria de Massas , Concentração de Íons de Hidrogênio , NADP/química , NADP/metabolismo , Oxirredutases/classificação , Oxirredutases/genética , Álcool Feniletílico/análise , Filogenia , Proteínas de Plantas/genética , Proteínas de Plantas/isolamento & purificação , Proteínas Recombinantes/biossíntese , Proteínas Recombinantes/isolamento & purificação , Estereoisomerismo
13.
Crit Rev Food Sci Nutr ; : 1-15, 2019 Jan 07.
Artigo em Inglês | MEDLINE | ID: mdl-30614265

RESUMO

Amino acids are the main contributors to tea (Camellia sinensis) flavor and function. Tea leaves contain not only proteinaceous amino acids but also specialized non-proteinaceous amino acids such as L-theanine and γ-aminobutyric acid (GABA). Here, we review different regulatory mechanisms of proteinaceous and non-proteinaceous amino acid formation in tea. The key findings were: (1) High accumulations of proteinaceous amino acids mainly result from protein degradation, which occurs in each tea stage, including preharvest, postharvest, manufacturing, and deep processing; (2) L-Theanine is the most represented non-proteinaceous amino acid that contributes to tea taste and function. Its accumulation is influenced more by the variety than by exogenous factors; and (3) GABA is the second most represented non-proteinaceous amino acid that contributes to tea function. Its formation, and resulting accumulation, are responses to stress. The combination of anoxic stress and mechanical damage are essential for a high GABA accumulation. An understanding of the biosynthesis, metabolism, and regulatory mechanisms of the proteinaceous and non-proteinaceous amino acids during the whole process from raw materials to tea products is necessary to safely and effectively alter tea flavor and function.

14.
Food Chem ; 270: 17-24, 2019 Jan 01.
Artigo em Inglês | MEDLINE | ID: mdl-30174031

RESUMO

Aromatic aroma compounds contribute to flavor of tea (Camellia sinensis (L.) O. Kuntze) and they are mostly derived from l-phenylalanine via trans-cinnamic acid or directly from l-phenylalanine. The objective of this study was to investigate whether an alternative pathway derived from l-phenylalanine via phenylpyruvic acid is involved in formation of aroma compounds in tea. Enzyme reaction with phenylpyruvic acid showed that benzaldehyde, benzyl alcohol, and methyl benzoate were derived from phenylpyruvic acid in tea leaves. Feeding experiments using [2H8]l-phenylalanine indicated that phenylpyruvic acid was derived from l-phenylalanine in a reaction catalyzed by aromatic amino acid aminotransferases (AAATs). CsAAAT1 showed higher catalytic efficiency towards l-phenylalanine (p ≤ 0.001) while CsAAAT2 showed higher catalytic efficiency towards l-tyrosine (p ≤ 0.001). Both CsAAATs were localized in the cytoplasm of leaf cells. In conclusion, an alternative pathway for the formation of aromatic aroma compounds derived from l-phenylalanine via phenylpyruvic acid occurred in tea leaves.


Assuntos
Fenilalanina/análise , Ácidos Fenilpirúvicos/análise , Folhas de Planta/química , Chá/química , Camellia sinensis/química
15.
Food Chem ; 276: 93-100, 2019 Mar 15.
Artigo em Inglês | MEDLINE | ID: mdl-30409668

RESUMO

l-Theanine is a specialized metabolite in tea (Camellia sinensis) leaves that contributes to tea function and quality. Yellow tea leaves (albino) generally have higher l-theanine contents than green tea leaves (normal), but the reason is unknown. The objective of this study was to investigate why l-theanine is accumulated in yellow tea leaves. We compared original normal leaves (green) and light-sensitive albino leaves (yellow) of cv. Yinghong No. 9. The l-theanine content was significantly higher in yellow leaves than in green leaves (p ≤ 0.01). After supplementation with [2H5]-l-theanine, yellow leaves catabolized less [2H5]-l-theanine than green leaves (p ≤ 0.05). Furthermore, most plants contained the enzyme catalyzing l-theanine conversion to ethylamine and l-glutamic acid. In conclusion, l-theanine accumulation in albino-induced yellow tea leaves was due to weak l-theanine catabolism. The differential accumulation mechanism differed from the l-theanine accumulation mechanism in tea and other plants.


Assuntos
Camellia sinensis/química , Glutamatos/análise , Folhas de Planta/química , Camellia sinensis/metabolismo , Etilaminas/análise , Etilaminas/metabolismo , Glutamatos/metabolismo , Ácido Glutâmico/análise , Ácido Glutâmico/metabolismo , Hidrolases/metabolismo , Folhas de Planta/metabolismo
16.
Plant Sci ; 277: 43-54, 2018 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-30466600

RESUMO

Dendrobium officinale is a precious traditional Chinese medicinal herb because it is abundant in mannose-containing polysaccharides (MCPs). GDP-mannose transporter (GMT), which translocates GDP-mannose into the Golgi lumen, is indispensable for the biosynthesis of MCPs. In this study, we found that the dominant polysaccharides in D. officinale were MCPs in a range of varieties and different physiological phases. After a positive correlation between the accumulation of mannose and the transcript levels of candidate GMT genes was found, three GMT genes (DoGMT1-3) were identified in D. officinale. DoGMT1, DoGMT2 and DoGMT3 exhibited the highest transcript level in stem that an organ for MCPs storage. All three DoGMT proteins were targeted to Golgi apparatus, and had a GDP binding domain (GXL/VNK) that was homologous to a specially characterized GMT protein GONST1 in Arabidopsis thaliana. Moreover, DoGMT1, DoGMT2 and DoGMT3 complemented a GDP-mannose transport-defective yeast mutant (vrg4-2), meanwhile they also demonstrated a higher GDP-mannose uptake activity. Therefore, we conclude that DoGMT1, DoGMT2 and DoGMT3 are able to transport GDP-mannose while the expression patterns of these genes correspond to the accumulation of MCPs in D. officinale. These findings support the importance of GMT genes from D. officinale in the biosynthesis of MCPs.

17.
Molecules ; 23(10)2018 Oct 18.
Artigo em Inglês | MEDLINE | ID: mdl-30340323

RESUMO

Tea (Camellia sinensis) cultivars with green leaves are the most widely used for making tea. Recently, tea mutants with white or yellow young shoots have attracted increasing interest as raw materials for making "high-quality" tea products. Albino teas are generallycharacterized as having metabolites of relatively high amino acid content and lower catechin content. However, little is known about aroma compounds in albino tea leaves. Herein, we compared original normal leaves (green) and light-sensitive albino leaves (yellow) of cv. Yinghong No. 9. GC-MS was employed to analyze endogenous tea aroma compounds and related precursors. Quantitative real time PCR was used to measure expression levels of genes involved in biosyntheses of tea aromas.The total contents of most endogenous free tea aromas, including aroma fatty acid derivatives, aroma terpenes, and aroma phenylpropanoids/benzenoids, and their glycosidically bound aroma compounds, were lower in yellow leaves than in green leaves. The content of the key precursor geranyl diphosphate (GDP) and expression levels of key synthetic genes involved in the formation of linalool, a major aroma compound in cv. Yinghong No. 9, were investigated. Linalool content was lower in albino-induced yellow leaves, which was due to the lower GDP content compared with normal green leaves.

18.
Crit Rev Food Sci Nutr ; : 1-14, 2018 Oct 02.
Artigo em Inglês | MEDLINE | ID: mdl-30277806

RESUMO

Metabolite formation is a biochemical and physiological feature of plants developed as an environmental response during the evolutionary process. These metabolites help defend plants against environmental stresses, but are also important quality components in crops. Utilizing the stress response to improve natural quality components in plants has attracted increasing research interest. Tea, which is processed by the tender shoots or leaves of tea plant (Camellia sinensis (L.) O. Kuntze), is the second most popular beverage worldwide after water. Aroma is an important factor affecting tea character and quality. The defense responses of tea leaves against various stresses during preharvest (tea growth process) and postharvest (tea manufacturing) processing can result in aroma formation. Herein, we summarize recent investigations into the biosyntheses of several characteristic aroma compounds prevalent in teas and derived from volatile fatty acid derivatives, terpenes, and phenylpropanoids/benzenoids. Several key aroma synthetic genes from tea leaves have been isolated, cloned, sequenced, and functionally characterized. Biotic stress (such as tea green leafhopper attack) and abiotic stress (such as light, temperature, and wounding) could enhance the expression of aroma synthetic genes, resulting in the abundant accumulation of characteristic aroma compounds in tea leaves. Understanding the specific relationships between characteristic aroma compounds and stresses is key to improving tea quality safely and effectively. [Formula: see text].

19.
World Neurosurg ; 120: 117-118, 2018 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-30179699

RESUMO

Cerebral venous anomaly (CVA) is a rare congenital malformation. Caput medusa and stripe signs were the most common imaging findings in CVA patients. Here, we present the case of a thrombosed CVA with a double annular enhancement in a 62-year-old male with a 2-month history of worsening headaches.

20.
Int J Mol Sci ; 19(10)2018 Sep 20.
Artigo em Inglês | MEDLINE | ID: mdl-30241372

RESUMO

Dendrobium officinale stems, including red and green stems, are widely used as a dietary supplement to develop nutraceutical beverages and food products. However, there is no detailed information on pigment composition of red and green stems. Here, we investigated the content and composition of pigments in red and green stems by Ultra-performance liquid chromatography quadrupole time-of-flight mass spectrometry and assessed the differential accumulation of anthocyanins at the molecular level. The color of peels in red stems was caused by the presence of anthocyanins in epidermal cells unlike the peels of green stems. The glucoside derivatives delphinidin and cyanidin are responsible for the red color. Within the D. officinale anthocyanidin biosynthetic pathway, DoANS and DoUFGT, coding for anthocyanidin synthase and UDP-glucose flavonoid-3-O-glucosyltransferase, respectively, are critical regulatory genes related to the differential accumulation of anthocyanidin. These findings provide a more complete profile of pigments, especially anthocyanin, in D. officinale stems, and lay a foundation for producing functional foods.

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