Lin Feng

Bio: Lin Feng is an academic researcher from Anhui Agricultural University. The author has contributed to research in topics: Chemistry & Solid-phase microextraction. The author has an hindex of 4, co-authored 14 publications receiving 137 citations.

Metabolic Flux Redirection and Transcriptomic Reprogramming in the Albino Tea Cultivar 'Yu-Jin-Xiang' with an Emphasis on Catechin Production.

Abstract: In this study, shade-induced conversion from a young pale/yellow leaf phenotype to a green leaf phenotype was studied using metabolic and transcriptomic profiling and the albino cultivar 'Yu-Jin-Xiang' ('YJX') of Camellia sinensis for a better understanding of mechanisms underlying the phenotype shift and the altered catechin and theanine production. Shaded leaf greening resulted from an increase in leaf chlorophyll and carotenoid abundance and chloroplast development. A total of 1,196 differentially expressed genes (DEGs) were identified between the 'YJX' pale and shaded green leaves, and these DEGs affected 'chloroplast organization' and 'response to high light' besides many other biological processes and pathways. Metabolic flux redirection and transcriptomic reprogramming were found in flavonoid and carotenoid pathways of the 'YJX' pale leaves and shaded green leaves to different extents compared to the green cultivar 'Shu-Cha-Zao'. Enhanced production of the antioxidant quercetin rather than catechin biosynthesis was correlated positively with the enhanced transcription of FLAVONOL SYNTHASE and FLAVANONE/FLAVONOL HYDROXYLASES leading to quercetin accumulation and negatively correlated to suppressed LEUCOANTHOCYANIDIN REDUCTASE, ANTHOCYANIDIN REDUCTASE and SYNTHASE leading to catechin biosynthesis. The altered levels of quercetin and catechins in 'YJX' will impact on its tea flavor and health benefits.

Chemical profile changes during pile fermentation of Qingzhuan tea affect inhibition of α-amylase and lipase.

Abstract: Qingzhuan tea (QZT), a post-fermented tea, has been reported to have anti-obesity and anti-hyperglycemic effects, perhaps due to bioactive compounds that inhibit lipase and α-amylase. It is unknown what chemical constituents' changes and what bioactive compounds occur during the manufacture of QZT. The aim of this study was to determine the secondary metabolites changes that occur during post-fermentation and how these changes affect the ability of QZT to inhibit the activities of lipase and α-amylase. During the processing steps, metabolites levels and their inhibitory effects on lipase and α-amylase were assessed. Changes in content and activities suggested that the first turn over or the second turn over was critical for the formation and conversion of bioactive compounds responsible for the anti-obesity and hypoglycemic effects. The relationship between constituents and activities was further evaluated by correlation analysis, which showed that amino acids and flavonoids might be responsible for the anti-obesity and anti-hyperglycemic effects of QZT. This study clarified that compounds were altered during pile fermentation of QZT and tentatively identified the bioactive compounds formed during QZT manufacture.

Comparing characteristic aroma components of bead-shaped green teas from different regions using headspace solid-phase microextraction and gas chromatography–mass spectrometry/olfactometry combined with chemometrics

Abstract: In this study, the aroma components of bead-shaped green teas were compared through headspace solid-phase microextraction (HS-SPME) and gas chromatography–mass spectrometry/olfactometry (GC–MS/O) coupled with chemometrics A total of 62 volatile compounds were identified in 16 green tea samples Notably, comparison of GC–MS/O and odour activity values (OAV) results revealed that nonanal, decanal, (E)-2-nonenal, β-ionone, and 1-octen-3-one were the most powerful aroma-active compounds that contributed to the aroma profile of the bead-shaped green teas Furthermore, multivariate statistical techniques (such as principal component analysis, partial least squares-discriminant analysis, and hierarchical cluster analysis) were used to characterise the bead-shaped green teas according to their geographical origin and the flavour characteristics of their volatile compounds Additionally, the variable importance in the projection method was used to identify 20 volatile markers that could successfully distinguish bead-shaped green teas on the basis of three flavour characteristics The results of the analysis revealed that HS-SPME and GC–MS/O coupled with chemometrics can provide an effective method for characterising and classifying bead-shaped green teas

Understanding different regulatory mechanisms of proteinaceous and non-proteinaceous amino acid formation in tea (Camellia sinensis) provides new insights into the safe and effective alteration of tea flavor and function.

Abstract: 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 acid...

Transcriptomic and phytochemical analysis of the biosynthesis of characteristic constituents in tea ( Camellia sinensis ) compared with oil tea ( Camellia oleifera )

Abstract: Tea plants (Camellia sinensis) are used to produce one of the most important beverages worldwide. The nutritional value and healthful properties of tea are closely related to the large amounts of three major characteristic constituents including polyphenols (mainly catechins), theanine and caffeine. Although oil tea (Camellia oleifera) belongs to the genus Camellia, this plant lacks these three characteristic constituents. Comparative analysis of tea and oil tea via RNA-Seq would help uncover the genetic components underlying the biosynthesis of characteristic metabolites in tea. We found that 3,787 and 3,359 bud genes, as well as 4,042 and 3,302 leaf genes, were up-regulated in tea and oil tea, respectively. High-performance liquid chromatography (HPLC) analysis revealed high levels of all types of catechins, theanine and caffeine in tea compared to those in oil tea. Activation of the genes involved in the biosynthesis of these characteristic compounds was detected by RNA-Seq analysis. In particular, genes encoding enzymes involved in flavonoid, theanine and caffeine pathways exhibited considerably different expression levels in tea compared to oil tea, which were also confirmed by quantitative RT-PCR (qRT-PCR). We assembled 81,826 and 78,863 unigenes for tea and oil tea, respectively, based on their differences at the transcriptomic level. A potential connection was observed between gene expression and content variation for catechins, theanine and caffeine in tea and oil tea. The results demonstrated that the metabolism was activated during the accumulation of characteristic metabolites in tea, which were present at low levels in oil tea. From the molecular biological perspective, our comparison of the transcriptomes and related metabolites revealed differential regulatory mechanisms underlying secondary metabolic pathways in tea versus oil tea.

Metabolomics analysis reveals the metabolic and functional roles of flavonoids in light-sensitive tea leaves.

Abstract: As the predominant secondary metabolic pathway in tea plants, flavonoid biosynthesis increases with increasing temperature and illumination. However, the concentration of most flavonoids decreases greatly in light-sensitive tea leaves when they are exposed to light, which further improves tea quality. To reveal the metabolism and potential functions of flavonoids in tea leaves, a natural light-sensitive tea mutant (Huangjinya) cultivated under different light conditions was subjected to metabolomics analysis. The results showed that chlorotic tea leaves accumulated large amounts of flavonoids with ortho-dihydroxylated B-rings (e.g., catechin gallate, quercetin and its glycosides etc.), whereas total flavonoids (e.g., myricetrin glycoside, epigallocatechin gallate etc.) were considerably reduced, suggesting that the flavonoid components generated from different metabolic branches played different roles in tea leaves. Furthermore, the intracellular localization of flavonoids and the expression pattern of genes involved in secondary metabolic pathways indicate a potential photoprotective function of dihydroxylated flavonoids in light-sensitive tea leaves. Our results suggest that reactive oxygen species (ROS) scavenging and the antioxidation effects of flavonoids help chlorotic tea plants survive under high light stress, providing new evidence to clarify the functional roles of flavonoids, which accumulate to high levels in tea plants. Moreover, flavonoids with ortho-dihydroxylated B-rings played a greater role in photo-protection to improve the acclimatization of tea plants.

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

Abstract: ‘Huangjinya’ is an excellent albino tea germplasm cultivated in China because of its bright colour 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 colour 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 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 colour changes in ‘Huangjinya’ are largely determined by the combined effects of flavonoid and carotenoid biosynthesis.