Integrated Transcriptomic and Metabolomic Analyses Reveal the Molecular and Metabolic Basis of Flavonoids in Areca catechu L.

Areca catechu L., of the Arecaceae family, is widely distributed in tropical Asia. In A. catechu, the extracts and compounds, including flavonoids, have various pharmacological activities. Although there are many studies of flavonoids, the molecular mechanism of their biosynthesis and regulation remains unclear in A. catechu. In this study, 331 metabolites were identified from the root, stem, and leaf of A. catechu using untargeted metabolomics, including 107 flavonoids, 71 lipids, 44 amino acids and derivatives, and 33 alkaloids. The transcriptome analysis identified 6119 differentially expressed genes, and some were enriched in the flavonoid pathway. To analyze the biosynthetic mechanism of the metabolic differences in A. catechu tissues, 36 genes were identified through combined transcriptomic and metabolomic analysis, in which glycosyltransferase genes Acat_15g017010 and Acat_16g013670 were annotated as being involved in the glycosylation of kaempferol and chrysin by their expression and in vitro activities. Flavonoid biosynthesis could be regulated by the transcription factors, AcMYB5 and AcMYB194. This study laid a foundation for further research on the flavonoid biosynthetic pathway of A. catechu.

槟榔（Areca catechu L.）隶属于棕榈科（Arecaceae），在热带亚洲地区广泛分布。槟榔中包括黄酮类（flavonoids）在内的提取物与单体化合物，具备多种药理学活性。尽管针对黄酮类化合物的研究已较为丰富，但槟榔中黄酮类生物合成与调控的分子机制仍未阐明。本研究采用非靶向代谢组学（untargeted metabolomics）技术，从槟榔的根、茎、叶中鉴定出331种代谢物，其中包含107种黄酮类、71种脂质、44种氨基酸及其衍生物，以及33种生物碱。转录组分析共鉴定出6119个差异表达基因，其中部分基因富集于黄酮类合成通路。为解析槟榔不同组织间代谢差异的生物合成机制，本研究通过转录组与代谢组联合分析，筛选出36个相关基因；其中，糖基转移酶（glycosyltransferase）基因Acat_15g017010与Acat_16g013670经表达与体外活性实验验证，被注释为参与山奈酚（kaempferol）与白杨素（chrysin）的糖基化修饰。转录因子AcMYB5与AcMYB194可调控黄酮类化合物的生物合成过程。本研究为后续深入探究槟榔的黄酮类生物合成通路奠定了基础。