De novo transcriptome combined with spectrophotometry and gas chromatography-mass spectrometer (GC-MS) reveals differentially expressed genes during accumulation of secondary metabolites in purple-leaf tea (Camellia sinensis cv Hongyafoshou)

To investigate differences in secondary metabolites and their related molecular mechanisms between purple-leaf tea and green-leaf tea, the transcriptomes and the secondary product profiles of the Camellia sinensis cultivars ‘Hongyafoshou’ (HF) and cultivar ‘Lvyafoshou’ (LF) were analysed and compared using GC-MS and spectrophotometric methods. The contents of anthocyanins, carotenoids, and total catechins were higher in HF than in LF. In total, 8,406 differentially expressed genes (DEGs) between HF and LF were identified. Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analyses revealed that the flavonoids, carotenoids and terpenoids metabolic pathways were highly enriched with DEGs. Differences in the expression of DEGs involved in these three pathways might be responsible for the high accumulation of secondary metabolites in HF. The small miRNA miR529 plays regulatory roles in these secondary metabolic pathways. The sensory quality of purple-leaf tea is higher than that of green-leaf tea, and these results from the combination of flavonoids, carotenoids, and terpenoids biosynthesis. Our study provides further insights into the molecular mechanisms underlying differences in secondary metabolite accumulation between HF and LF.

为探究紫叶茶与绿叶茶的次生代谢产物及其相关分子机制差异，本研究采用气相色谱-质谱联用（GC-MS）与分光光度法，对茶树（Camellia sinensis）品种‘红芽佛手’（HF）与‘绿芽佛手’（LF）的转录组及次生产物谱进行分析与比较。相较于LF，HF中花青素、类胡萝卜素与儿茶素总含量均更高。本研究共鉴定出HF与LF间的差异表达基因（differentially expressed genes, DEGs）共计8406个。京都基因与基因组百科全书（Kyoto Encyclopedia of Genes and Genomes, KEGG）富集分析显示，类黄酮、类胡萝卜素与萜类代谢通路均显著富集有DEGs。参与上述三条代谢通路的DEGs表达差异，可能是HF中次生代谢产物高度积累的关键原因。微小RNA miR529在这些次生代谢通路中发挥调控作用。紫叶茶的感官品质优于绿叶茶，该特性与类黄酮、类胡萝卜素及萜类的生物合成途径协同相关。本研究为阐明HF与LF间次生代谢产物积累差异的分子机制提供了进一步的理论见解。