Integrated Metabolomic and Transcriptomic Analysis Reveals Differential Flavonoid Accumulation and Its Underlying Mechanism in Fruits of Distinct Canarium album Cultivars

Canarium albumfruit has great potential to be consumed as a raw material not only for food but also medicine. The diverse active metabolites composition and content ofC. albumfruits greatly affect their pharmacological effects. However, up to now, there has been no report on the global metabolome differences among fruits from distinctC. albumcultivars. In our present study, by using non-targeted metabolomics techniques, we identified 87 DAMs (differentially accumulated metabolites) including 17 types of flavonoids from fruits of four differentC. albumcultivars. KEGG (Kyoto Encyclopedia of Genes and Genomes) pathway enrichment analysis revealed that the flavone and flavonol biosynthesis- and flavonoid biosynthesis-related DAMs were major factors determining their metabolome differences. Comparative transcriptomic analysis revealed that 15 KEGG pathways were significantly enriched by genes of the identified 3655 DEGs (differentially expressed genes) among differentC. albumcultivars. Consistent with the metabolome data, flavonoid biosynthesis-related DEGs, including eight key structural genes (such asFLS,CCoAOMT,CHI,C4H,DFR,LAR, andC3′H, etc.) and several regulatory transcription factor (TF) genes (including 32MYBsand 34bHLHs, etc.), were found to be significantly enriched (p< 0.01). Our study indicated that the differential expression of flavonoid biosynthesis-related genes and accumulation of flavonoids played dominant roles in the various metabolome compositions of fruits from differentC. albumcultivars.Keywords:Canarium album;flavonoid;metabolomics;transcriptomics;gene expression