关键词: 胡萝卜, 广泛靶向代谢组学, 风味物质, 萜类代谢物, 差异代谢物, 品质

Abstract:

【Objective】 Terpenoid metabolites serve as primary indicators for assessing the quality of carrot flavor, which influence the taste and overall flavor quality of carrots significantly. This study compared the metabolites of flavor components in mature fleshy carrot roots exhibiting pronounced sweetness group and bitterness group, which could offer valuable insights for identifying key flavor components and enhancing the cultivation and exploitation of superior genetic resources.【Method】Efficient methods for detecting and identifying metabolites were established for carrot metabolomics research. Initially, a high-throughput metabolomic analysis platform was developed using UPLC-MS/MS to analyze terpene metabolites in carrots and to identify those influencing flavor quality. Differential metabolites were screened based on OPLS-DA results using VIP and log2FC values, with thresholds set at VIP>1 and fold changes of ≥2 and ≤0.5. 【Result】 A total of 50 terpenoid metabolites were screened out and exhibited significant differences, with 12 up-regulated and 2 down-regulated. Notable upregulated metabolites included Genipine (0.754), Japonicumin B (0.936), oxyphyllanene A (1.03), carvyl acetate (1.04), and 3-(3'-hydroxybutyl)-2, 4, 4-trimethylcyclohexan-2, 5-dienone (0.662). Dehydrodigitoxin (0.617) was significantly down-regulated. In terms of terpene content, those bitter carrots showed higher levels of Normelanothyrsin A (16.98), Curcumenol (17.57), and Genipin (15.32), while sweet carrots exhibited higher levels of Normelanothyrsin A (17.61), isothyrsin alcohol (16.01), and Curcuma alcohol (18.73). Top metabolites based on p-values included micrantholide (0.994), pyrodialdehyde (0.991), methyl (E)-5, 11-dihydroxy-4-(((Z)-2-2-enoyl methylbut-)foxy)-, 10-dimethylene-2-3 oxo-2 filling a, 4, 5, 8, 9, 10, 11, 11a-decahydrocyclodeca[b]furan-6-carboxylate (0.978), (3R)-3-hydroxy-ionone (0.974), and Blumenol A (0.969). Cluster analysis was employed to compare metabolite profiles between the two carrot groups, revealing significantly higher metabolite content in group 3 than that in group -3. Differential metabolite annotation and enrichment analysis were performed using the KEGG database.【Conclusion】Terpenoid metabolites, including Gennipine, Japonicumin B, oxyphyllanene A, carvyl acetate, Normelanothyrsin A, curcumenol, isocarbamol, dehydrodigitoxin, and micrantholide, were the primary compounds influencing the flavor of carrots. These compounds were believed to play a crucial role in determining the characteristic taste of carrots.

Key words: carrots（Daucus carota var. sativa Hoffm.）, broadly targeted metabolomics, flavor substance, terpene metabolites, differential metabolite, quality