Integrative analysis of the metabolome and transcriptome provides novel insights into the mechanisms of flavonoid biosynthesis in Camellia lanceoleosa

Flavonoids, the effective material basis for the anti-thrombotic, anti-myocardial ischemia, and anti-dementia drug system framework, are one class of the main bioactive compounds in tea-oil Camellia. However, the molecular mechanism of the transcription regulation of flavonoid biosynthesis in tea-oil Camellia has not been fully investigated. Camellia lanceoleosa (C. lanceoleosa) is a diploid species of section Oleifera with genomic information, which has high value in scientific research and application. To comprehend the molecular mechanism of flavonoid biosynthesis in C. lanceoleosa, five different tissues (roots, stems, leaves, flower buds, and seeds) were used to perform an integrated analysis of the metabolome and transcriptome. Overall, 1,437 metabolites were identified and quantified, among which 488 common metabolites and 92 tissue-specific metabolites were detected in different tissues of C. lanceoleosa. Notably, the most abundant metabolite class was the flavonoids in the detected tissues of C. lanceoleosa. Furthermore, the differential metabolites and genes were also mainly enriched in flavonoid biosynthesis. A total of 145 differentially accumulated flavonoids and 65 differentially expressed structural genes were found within the biosynthesis of flavonoid in C. lanceoleosa. The expression patterns of most genes were consistent with the flavonoid accumulation patterns in the corresponding pathways. Using weighted gene coexpression network analysis, five gene modules and several candidate hub genes involved in flavonoid biosynthesis were investigated in different tissues of C. lanceoleosa, these genes included differentially expressed structural genes (PAL, CHS, DFR, and ANR) and transcription factors (bHLHs, MYBs, WRKYs, NACs, and SPL6). These results provide useful genetic resources for studying the molecular insights into the regulatory network of flavonoid biosynthesis in C. lanceoleos.