Metabolome and Transcriptome Sequencing Analysis Reveals Anthocyanin Metabolism in Pink Flowers of Anthocyanin-Rich Tea (Camellia sinensis)

Abstract

Almost all flowers of the tea plant (Camellia sinensis) are white, which has caused few researchers to pay attention to anthocyanin accumulation and color changing in tea flowers. A new purple-leaf cultivar, Baitang purple tea (BTP) was discovered in the Baitang Mountains of Guangdong, whose flowers are naturally pink, and can provide an opportunity to understand anthocyanin metabolic networks and flower color development in tea flowers. In the present study, twelve anthocyanin components were identified in the pink tea flowers, namely cyanidin O-syringic acid, petunidin 3-O-glucoside, pelargonidin 3-O-beta-d-glucoside, which marks the first time these compounds have been found in the tea flowers. The presence of these anthocyanins seem most likely to be the reason for the pink coloration of the flowers. Twenty-one differentially expressed genes (DEGs) involved in anthocyanin pathway were identified using KEGG pathway functional enrichment, and ten of these DEG’s screened using venn and KEGG functional enrichment analysis during five subsequent stages of flower development. By comparing DEGs and their expression levels across multiple flower development stages, we found that anthocyanin biosynthesis and accumulation in BTP flowers mainly occurred between the third and fourth stages (BTP3 to BTP4). Particularly, during the period of peak anthocyanin synthesis 17 structural genes were upregulated, and four structural genes were downregulated only. Ultimately, eight critical genes were identified using weighted gene co-expression network analysis (WGCNA), which were found to have direct impact on biosynthesis and accumulation of three flavonoid compounds, namely cyanidin 3-O-glucoside, petunidin 3-O-glucoside and epicatechin gallate. These results provide useful information about the molecular mechanisms of coloration in rare pink tea flower of anthocyanin-rich tea, enriching the gene resource and guiding further research on anthocyanin accumulation in purple tea.

Metabolome and Transcriptome Analysis Reveals Putative Genes Involved in Anthocyanin Accumulation and Coloration in White and Pink Tea (Camellia sinensis) Flower

“…In order to validate the RNA Seq results, the quantitative real-time PCR (qRT-PCR) was performed on the petal samples at the five development stages as described by Rothenberg et al [67]. Total RNA isolation was conducted using RNAqueous™ Total RNA Isolation Kit according to the protocol.…”

Integrated metabolic profiling and transcriptome analysis of pigment accumulation in diverse petal tissues in the lily cultivar ‘Vivian’

“…The expression patterns of some flower-color variation in plants were similar with 'Vivian'. Differences in LBG expression caused color differences in bicolor peony "Shima Nishiki" [75], pink camellia [76], and yellow/orange variation in Gentiana [77]. Therefore, the expression of LBGs can affect the pigmentation in these plants.…”

Dynamic Transcriptome Changes Related to Oil Accumulation in Developing Soybean Seeds

“…WGCNA has been used to uncover a network module containing 34 genes, which was highly correlated ( r = 0.95, p = 9.0 × 10 −13 ) with apple anthocyanin contents [8]. Another study identified eight key genes with direct impact on biosynthesis and accumulation of three flavonoid compounds during the flower development of Camellia sinensis using WGCNA [16].…”