No abstract

Tea (Camellia sinensis) flowers are normally white, even though the leaves could be purple. We previously discovered a specific variety with purple leaves and flowers. In the face of such a phenomenon, researchers usually focus on the mechanism of color formation but ignore the change of aroma. The purple tea flowers contain more anthocyanins, which belong to flavonoids. Meanwhile, phenylalanine (Phe), derived from the shikimate pathway, is a precursor for both flavonoids and volatile benzenoid–phenylpropanoids (BPs). Thus, it is not clear whether the BP aroma was attenuated for the appearance of purple color. In this study, we integrated metabolome and transcriptome of petals of two tea varieties, namely, Zijuan (ZJ) with white flowers and Baitang (BT) with purple flowers, to reveal the relationship between color (anthocyanins) and aroma (volatile BPs). The results indicated that in purple petals, the upstream shikimate pathway promoted for 3-deoxy-D-arabino-heptulosonate 7-phosphate synthase (DAHPS) was elevated. Among the increased anthocyanins, delphinidin-3-O-glucoside (DpG) was extremely higher; volatile BPs, including benzyl aldehyde, benzyl alcohol, acetophenone (AP), 1-phenylethanol, and 2-phenylethanol, were also enhanced, and AP was largely elevated. The structural genes related to the biosynthesis of volatile BPs were induced, while the whole flavonoid biosynthesis pathway was downregulated, except for the genes flavonoid 3′-hydroxylase (F3′H) and flavonoid 3′,5′-hydroxylase (F3′5′H), which were highly expressed to shift the carbon flux to delphinidin, which was then conjugated to glucoside by increased bronze-1 (BZ1) (UDP-glucose: flavonoid 3-O-glucosyltransferase) to form DpG. Transcription factors (TFs) highly related to AP and DpG were selected to investigate their correlation with the differentially expressed structural genes. TFs, such as MYB, AP2/ERF, bZIP, TCP, and GATA, were dramatically expressed and focused on the regulation of genes in the upstream synthesis of Phe (DAHPS; arogenate dehydratase/prephenatedehydratase) and the synthesis of AP (phenylacetaldehyde reductase; short-chain dehydrogenase/reductase), Dp (F3′H; F3′5′H), and DpG (BZ1), but inhibited the formation of flavones (flavonol synthase) and catechins (leucoanthocyanidin reductase). These results discovered an unexpected promotion of volatile BPs in purple tea flowers and extended our understanding of the relationship between the BP-type color and aroma in the tea plant.

Compound green tea is able to decrease the body weight and regulate the plasma lipid indexes, as well as make the abnormal metabolic state return to normal by intervening in different metabolic pathways to partially reverse the lipid metabolism disorder.

Blister blight infected with Exobasidium vexans is one of the most destructive foliar diseases that seriously affects the quality and yield of tea. This research was to investigate the metabolite changes of healthy and infected leaves on tea cultivar “Fuding Dabaicha”, as well as further explore the potential antimicrobial substances against E. vexans infection. In total, 1166 compounds were identified in the whole stage of infection, among which 73 different common compounds were significantly accumulated involved in the important antimicrobial substances of flavonoids and phenolic acids, including kaempferol (3,5,7,4'-tetrahydroxyflavone), kaempferol-3-O-sophoroside-7-O-glucoside, phloretin, 2,4,6-trihydroxybenzoic acid, galloylprocyanidin B4, and procyanidin C1 3'-O-gallate, which indicated that these metabolites might positively dominate the resistance to E. vexans. Furthermore, the relevant biological pathways, such as “Flavone and flavonol biosynthesis”, “Flavo-noid biosynthesis”, and “Phenylpropane pathway”, were more closely related to the resistance against E. vexans. Additionally, total flavonoids, phenolics, alkaloids and terpenoids contributing to antimicrobial and antioxidant capacity altered significantly in four different infection periods, especially the Leaf_S2 stage (the second stage of infection) in which the concentration accumulated the most. The leaves affected by E. vexans infection at the second stage had the relatively highest antioxidant activity. Accordingly, this study provided a theoretical support and comprehensive insights into the effects on the metabolite changes, tea quality components and antioxidant activity of blister blight caused by E. vexans.