Comprehensive Characterization of Metabolites in Multiplier Onion Reveals Key Genetic Regulators of Nutritional Quality

Scientists at the Chinese Academy of Agricultural Sciences have conducted a thorough investigation into the metabolic profile of multiplier onion, providing a comprehensive atlas of its nutritional components. The study aimed to identify potential genetic regulators of nutritional quality in multiplier onion, a crop with dual purposes as a culinary ingredient and medicinal resource. Funded by several institutions, including the National Modern Agricultural Industry Technology System Construction Special Fund Project and the Natural Science Foundation of China, the researchers employed ultra-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) to analyze the metabolites present in the bulbs of five genetically distinct accessions. The analysis revealed a high abundance of flavonoids and essential amino acids, with significant variations observed among the accessions. Transcriptome analysis and correlation and network analysis further identified crucial candidate regulatory genes for the biosynthesis and metabolism of lipids, flavonoids, phenolic acids, and amino acids.

Key Takeaways:

• The study identified 659 metabolites, including lipids, flavonoids, phenolic acids, amino acids, saccharides, and alcohols, organic acids, alkaloids, nucleotides, and derivatives.
• The bulbs exhibited a high abundance of flavonoids (e.g., quercetin, kaempferol, naringenin, isorhamnetin) and eight essential amino acids (valine, threonine, leucine, isoleucine, lysine, methionine, histidine, and tryptophan).
• Comparative analysis revealed that 366 differentially accumulated metabolites were identified among the five accessions, many of which were significantly enriched in pathways related to flavonoid biosynthesis, amino acid biosynthesis, and metabolism.
• Transcriptome analysis indicated that differentially expressed genes (DEGs) across the five accessions were significantly enriched in flavonoid biosynthesis, various amino acid biosynthesis and metabolism processes, such as 'tyrosine metabolism', 'phenylalanine, tyrosine, and tryptophan biosynthesis', 'cysteine and methionine metabolism', and 'arginine and proline metabolism'.
• Correlation and network analysis identified several crucial candidate regulatory genes for the biosynthesis and metabolism of lipids, flavonoids, phenolic acids, and amino acids.

Statistics:

• 659 metabolites identified in the analysis
• 366 differentially accumulated metabolites among the five accessions
• 5 genetically distinct accessions analyzed
• 14 amino acids identified as being essential
• 5 essential amino acids identified in the bulbs, including valine, threonine, leucine, isoleucine, and lysine

Sources:

• Comprehensive Characterization of Metabolites in Multiplier Onion Bulbs and Identification of Regulatory Genes for Nutritional Improvement. Foods, 2025,14(19):3290.
• Chinese Academy of Agricultural Sciences. State Key Laboratory of Vegetable Biobreeding, Institute of Vegetables and Flowers.
• National Modern Agricultural Industry Technology System Construction Special Fund Project
• Natural Science Foundation of China
• Key R&,D Program of Shandong Province of China
• Innovation Engineering Project of Chinese Academy of Agricultural Sciences
• Safe Preservation Project of Crop Germplasm Resources of Ministry of Finance
• National Horticultural Germplasm Centre Project