Study On Polyphenols Biosynthesis Of Tea [Camellia Sinensis (L.) O. Kuntze] During Seedling Photomorphogenesis

Polyphenols are the main components of secondary metabolites in tea plant([Camelliasinensis (L.) O. Kuntze])，including chachins, flavone and flavonol glycosides, phenolicacids and depsides, anthocyanins and leucoanthocyanidins. Polyphenols are the productsderived from multiple branches of shikimic acid–phenylpropanoid–flavonoidbiosynthetic pathway. As the important energy source and environmental signal, lightradiation can regulate the accumulation of polyphenols in plants.In this study, to better understand the influence of light signal in polyphenolsbiosynthetic pathway in tea plant, with tea seedlings living in low light as materials, wedetected the changes of polyphenol accumulation, enzyme activity and concerned geneexpression during the first-week photomorphism process. The main results were concludedas follows.1. Qualitative analysis based on LC-TOF/MS was applied to identify the mainpolyphenols in tea seedlings. A reversed-phase PHPLC coupled with SPE was developedto purify and to prepare high purity3-O-galloyquinic acid and β-D-glucogalline from freshtea leaves. The obtained fractions were successfully identified by1H-NMR and13C-NMR.2. We treated tea seedlings with light in different ways. HPLC quantify analysisshowed, in tea seedlings, exposure to light significantly reduced the level of benzoic acidderivatives, increased the level of phenylpropionic acid devatives, and the accumulation ofβ-D-glucogalline in the dark growning tea seedling stem was extremely abundant.Exposure to light processing also increased the level of nongalloylated catechins andglucoside flavonol. However, light processing didn’t increase the level of galloylatedcatechins. In addition, exposure to light also increased the activity ofepigallocatechin-3-gallate hydrolase.3. The qRT-PCR analysis showed, during the first-week photomorphism process oftea seedling, the expressions of photomorphism associated genes (COP1and HY5) wereincreased significantly; the expression of shikimic acid pathway gene DHD/SDH wasinhibited significantly; the expressions of genes invole in flavnoid pathway (F3’H、F3’5’H、ANR1、ANR2、DFR1、DFR2、ANS) were increased, except ANR1; forglucosyltransferase genes, UGT75E1and UGT73E1were reduced in stem and leaf,while,UGT75E2, UGT75E3and UGT78E1were increased in leaf, reduced in stem,UGT72F1was increased in srem and leaf; in addition, the expressions of predictedtranscription factor genes associated with the flavnoid pathway (MYB4-5、MYB4-6、MYB4-7and WD40) were all increased.