Melatonin is a biological hormone that plays crucial roles in stress tolerance. In this study, we investigated the effect of exogenous melatonin on abiotic stress in the tea plant. Under cold, salt and drought stress, increasing malondialdehyde levels and decreasing maximum photochemical efficiency of PSII were observed in tea leaves. Meanwhile, the levels of reactive oxygen species (ROS) increased significantly under abiotic stress. Interestingly, pretreatment with melatonin on leaves alleviated ROS burst, decreased malondialdehyde levels and maintain high photosynthetic efficiency. Moreover, 100 μM melatonin-pretreated tea plants showed high levels of glutathione and ascorbic acid and increased the activities of superoxide dismutase, peroxidase, catalase and ascorbate peroxidase under abiotic stress. Notably, melatonin treatments can positively up-regulate the genes (CsSOD, CsPOD, CsCAT and CsAPX) expression of antioxidant enzyme biosynthesis. Taken together, our results confirmed that melatonin protects tea plants against abiotic stress-induced damages through detoxifying ROS and regulating antioxidant systems.

‘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.

Green and dark tea extract (GTE/DTE) ameliorate chemical-induced colitis in mice; however, the role of gut microbiota in the anticolitis effects of green and dark tea in mice remains unclear. This study aims to explore the role of modulations in gut microbes mediated by green and dark tea in colitis mice by fecal microbiota transplantation (FMT). Our results indicated that GTE and DTE (5 mg/kg bodyweight/day for 4 weeks) exhibited prebiotic effects on the donor mice. Moreover, the FMT treatments (transferring the microbiota daily from the 1 g/kg bodyweight fecal sample to each recipient) indicated that, compared with the fecal microbiota from the normal diet-treated donor mice, the fecal microbiota from the GTE- and DTE-treated donor mice significantly ameliorate colitis-related symptoms (e.g., loss of bodyweight, colonic inflammation, loss of barrier integrity, and gut microbiota dysbiosis) and downregulated the TLR4/MyD88/NF-κB pathway. Collectively, GTE and DTE ameliorate chemical-induced colitis by modulating gut microbiota.

Ripened pu-erh tea has the biological activity of antioxidation and anti-inflammation, which inhibits the related parameters of colitis. However, the role of storage-induced changes in bioactive ingredients of ripened pu-erh tea in colitis remains unclear. In this study, 3.5% dextran sulfate sodium-induced colitis mice were treated with 10 mg/kg bw/day extracts, aged 14 years (P2006) and unaged (P2020) ripened pu-erh tea, respectively, for 1 week. We found that ripened pu-erh tea, especially P2006, inhibited the intestinal oxidative stress-mediated inflammation pathway (TLR4/MyD88/ROS/p38MAPK/NF-κB p65), upregulated the expression of intestinal tight junction proteins (Mucin-2, ZO-1, occludin), promoted M2 polarization of macrophages, and in turn, improved the intestinal immune barrier, which stemmed from the reshaping of intestinal microbiota (e.g., increased Lachnospiraceae_NK4A136_group and Akkermansia levels). Our results speculate that drinking aged ripe pu-erh tea (10 mg/kg bw/ day in mice, a human equivalent dose of 7 g/60 kg bw/day) has a practical effect on alleviating and preventing the development of intestinal inflammation.

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Extracting surface water distribution with satellite imagery has been an important subject in remote sensing. Spectral indices of water only use information from a limited number of bands, thus they may have poor performance from pixels contaminated by ice/snow, clouds, etc. The detection algorithms using information from all spectral bands, such as constrained energy minimization (CEM), could avoid this problem to some extent. However, these are mostly designed for hyperspectral imagery, and may fail when applied to multispectral data. It has been proved that adding linearly irrelevant data to original data could improve the performance of CEM. In this study, two kinds of linearly irrelevant data are added for water extraction: the spectral indices and the spectral similarity metric data. CEM is designed for targets with low-probability distribution in an image, but water bodies do not always satisfy this condition. We thereby impose a sensible coefficient for each pixel to form the weighted autocorrelation matrix. In this study, the weight is based on the orthogonal subspace projection, so this new method is named Orthogonal subspace projection Weighted CEM (OWCEM). The newly launched Landsat 8 images over two lakes, the Hala Lake in China with ice/snow distributed in the north, and the Huron Lake in OPEN ACCESSWater 2015, 7 795North America, a lake with a very large surface area, are selected to test the accuracy and robustness of our algorithm. The Kappa coefficient and the receiver operating characteristic (ROC) curve are calculated as an accuracy evaluation standard. For both lakes, our method can greatly suppress the background (including ice/snow and clouds) and extract the complete water surface with a high accuracy (Kappa coefficient > 0.96).

This study investigated the protective effects of pu-erh tea extract (PTE) on alcohol-induced microbiomic and metabolomic disorders. In chronic alcohol-exposed mice, PTE ameliorated chronic alcoholic consumption-induced oxidative stress, inflammation, lipid accumulation, and liver and colon damage through modulating microbiomic and metabolomic responses. PTE restored the alcohol-induced fecal microbiota dysbiosis by elevating the relative abundance of potentially beneficial bacteria, for example, Bifidobacterium and Allobaculum, and decreasing the relative abundance of potentially harmful bacteria, for example, Helicobacter and Bacteroides. The alcohol-induced metabolomic disorder was modulated by PTE, which was characterized by regulations of lipid metabolism (sphingolipid, glycerophospholipid, and linoleic acid metabolism), amino acid metabolism (phenylalanine and tryptophan metabolism), and purine metabolism. Besides, the bacterial metabolites of phytochemicals in PTE might contribute to the protective effects of PTE. Overall, PTE could be a functional beverage to treat chronic alcohol consumption-induced microbiomic and metabolomic disorders.