Search

Automatic thermal desorption-gas chromatography-mass spectrometry (ATD-GC-MS) was used to capture and detect environmental volatile components in Tieguanyin tea at the key stages of the fine manipulation process, and short time series expression miner (STEM) and partial least squares-discriminant analysis (PLS-DA) were used to analyze the volatile components. The results showed that a total of 122 volatile components belonging to eight chemical classes, i.e., alcohols, esters, olefins, alkanes, aldehydes, aromatic hydrocarbons, ketones and other compounds were identified, esters being the major ones. The STEM results showed that the detected volatile components could be divided into 19 trends, and there was significant enrichment in two trend models. Among them, the levels of 2-butanol, ethyl acetate, isovaleraldehyde, 3-methyl-1-butanol, 1-hexanol, 2-heptanol, methyl hexanoate, 6-methyl-5-hepten-2-one, and octyl isobutyrate, which have a special aroma, increased significantly with increasing number of fine manipulation cycles. PLS-DA could effectively distinguish between tossing and sun withering, and seven characteristic volatile components (variable importance in the projection (VIP) > 1) were common to the two stages including (Z)-4-hexen-1-yl acetate, (E)-butanoic acid, 3-hexenyl ester, (E)-3-hexen-1-ol, 2-hexenal, 3-methyl-butanenitrile, (E)-4,8-dimethylnona-1,3,7-triene and (Z)-3,7-dimethyl-1,3,6-octatriene. The proportion and composition of environmental volatile components in Tieguanyin tea changed during the fine manipulation process. Most of the volatile components showed obvious and regular changes. The seven shared volatile components could be considered as aroma indexes for judging intelligent fine manipulation.

In this study, the metabolites in the flowers and leaves of single- and double-petal jasmine were determined and compared by ultra-high performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) combined with multivariate statistical analysis. The results showed that a total of 935 metabolites were identified from all samples, including amino acids and derivatives, phenolic acids, nucleotides and derivatives, flavonoids, lignans and coumarins, tannins, alkaloids, terpenoids, organic acids, lipids, saccharides and sugar alcohols, vitamins, and other compounds. Totally 348 and 337 significantly changed metabolites (SCMs) from the flowers and leaves were identified between single- and double-petal jasmine, respectively. The major SCMs were phenolic acids, flavonoids, lipids, saccharides and sugar alcohols. The leaves of double-petal jasmine were rich in flavonoids. In addition, the flavone and flavonol biosynthesis pathways were more active, leading to accumulation of more compounds with biological and pharmacological activities such as nicotiflorin, cynaroside, quercetin, quercetin-3-O-glucoside, astragalin, and afzelin. Lipids were the major unique metabolites in the flowers and leaves of single-petal jasmine. The unique metabolites in the flowers and leaves of double-petal jasmine were more diverse and abundant than those in single-petal jasmine. The results of this study are very meaningful for guiding the development of jasmine resources.

Shaking is one of the key processes contributing to the quality formation of oolong tea. As an abiotic stress factor, mechanical stress leads to a series of physiological and biochemical changes in plants through various biological effects, which has been widely used in the processing of scented black tea, scented white tea, scented green tea and other tea types to improve their quality. In order to ascertain the physiological changes of green tea leaves in response to mechanical stress, postharvest fresh shoots with 3–4 leaves?from the tea cultivar ‘Tieguanyin’ were evaluated for changes in water content, photosystem II (PS II) parameters, antioxidant enzyme activities and subcellular structure under natural spreading or continuous vibration stress treatment after withering. Compared with naturally spread leaves and withered leaves, the water content in the leaves subjected to vibration stress was not significantly different within the first 30 min of vibration (P > 0.05) but was significantly lower at 60 min (P < 0.05). The green-grassy odor became stronger with increasing vibration time, the refreshing aroma became weaker, and the clear compact lamellar structures of the chloroplast and the thylakoid were gradually loosened, deformed, shrunk, and disrupted. The number of starch granules increased significantly at 5 min, and the number of osmiophilic granules increased significantly at 15 min, resulting in the formation of aggregates. The actual photosynthetic efficiency Y (II) and photochemical quenching coefficient (qP) of PS II generally showed a decreasing trend with increasing vibration time, and the electron transfer rate (ETR) declined initially and then rose. The Y (II) and ETR at 5 and 10 min of vibration were significantly lower than those observed in naturally spread leaves (P < 0.05). The quantum yield Y (NO) of non-regulated energy dissipation increased with the prolongation of vibration stress treatment time, and was significantly higher than that of naturally spread leaves at 30 min (P < 0.05). The relative conductivity of tea leaves under vibration stress for 10 min was significantly higher than that of naturally spread leaves (P < 0.05). The activities of ascorbate peroxidase, dehydroascorbate reductase and glutathione reductase in tea leaves under vibration stress for 5 and 10 min were higher than those in naturally spread leaves. Vibration treatment (for up to 30 min) did not show significant variations in water content, but enhanced the green-grassy odor. Continuous vibration treatment caused cell injuries by increasing the cell membrane permeability, thereby facilitating the release of intracellular contents and increasing cell conductivity. At the subcellular level, vibration treatment promoted thylakoid degradation and severely damaged chloroplasts, thus destroying PS II stability. Meanwhile, it protected tea leaf cells against mechanical stress-induced damage by elevating the activities of defense enzymes. Taken together, this study lays a foundation for the regulating of shaking during the processing of oolong tea.

Gold-based nanoparticles for surface-enhanced Raman scattering (SERS) imaging show great potential for precise tumor detection and photothermal therapy (PTT). However, the metabolizability of gold nanoparticles (Au NPs) raises big concerns. Herein, we designed a core-shelled nanostructure of copper sulfide (CuS)-coated Au NPs with surface pegylation (PEG-Au@CuS NSs). The excreted Au in the gallbladders at 1 h and 4 h in mice injected with PEG-Au@CuS NSs was 8.2- and 19.1-fold of that with the pegylated Au NPs (PEG-AuNPs) of the same Au particle size, respectively. By loading the Raman reporter 3,3′-Diethylthiatricarbocyanine iodide (DTTC) in the core–shell junction of PEG-Au@CuS NSs, the PEG-Au-DTTC@CuS NSs exhibited the Raman signal-to-noise (S/N) ratio of 4.01 after 24 h of intravenous (IV) injection in the mice bearing an orthotopic CT26-Luc colon tumor. By contrast, the DTTC-coated PEG-AuNPs (PEG-Au-DTTC NPs) achieved an S/N ratio of 2.71. Moreover, PEG-Au-DTTC@CuS NSs exhibited an increased photothermal conversion effect compared with PEG-Au-DTTC NPs excited with an 808-nm laser. PEG-Au-DTTC@CuS NSs enabled intraoperative SERS image-guided photothermal therapy for a complete cure of the colon tumor-bearing mice. Our data demonstrated that the PEG-Au-DTTC@CuS NSs are promising intraoperative Raman image-guided theranostic nanoplatform with enhanced hepatobiliary excretion. [ABSTRACT FROM AUTHOR]

Main conclusion: The alpha-amylase and beta-amylase genes have been identified from tea plants, and their bioinformatic characteristics and expression patterns provide a foundation for further studies to elucidate their biological functions. Alpha-amylase (AMY)- and beta-amylase (BAM)-mediated starch degradation plays central roles in carbohydrate metabolism and participates extensively in the regulation of a wide range of biological processes, including growth, development and stress response. However, the AMY and BAM genes in tea plants (Camellia sinensis) are poorly understood, and the biological functions of these genes remain to be elucidated. In this study, three CsAMY and nine CsBAM genes from tea plants were identified based on genomic and transcriptomic database analyses, and the genes were subjected to comprehensive bioinformatic characterization. Phylogenetic analysis showed that the CsAMY proteins could be clustered into three different subfamilies, and nine CsBAM proteins could be classified into four groups. Putative catalytically active proteins were identified based on multiple sequence alignments, and the tertiary structures of these proteins were analyzed. Cis-element analysis indicated that CsAMY and CsBAM were extensively involved in tea plant growth, development and stress response. In addition, the CsAMY and CsBAM genes were differentially expressed in various tissues and were regulated by stress treatments (e.g., ABA, cold, drought and salt stress), and the expression patterns of these genes were associated with the postharvest withering and rotation processes. Taken together, our results will enhance the understanding of the roles of the CsAMY and CsBAM gene families in the growth, development and stress response of tea plants and of the potential functions of these genes in determining tea quality during the postharvest processing of tea leaves. [ABSTRACT FROM AUTHOR]