Tree Genetics and Molecular Breeding 2025, Vol.15, No.5, 185-191 http://genbreedpublisher.com/index.php/tgmb 187 discovering new aroma components and analyzing the overall metabolic network. In the study of loquat aroma, non-targeted LC-MS/MS methods have been used to systematically analyze the metabolite composition of different tissues and varieties, revealing the diversity and tissue specificity of aroma components (Wang, 2021). 4 Integration of Metabolomics with Other Omics 4.1 Transcriptomics and gene–metabolite correlations The combined analysis of transcriptomics and metabolomics revealed the synthetic genes of metabolites related to the aroma of loquat. Researchers identified candidate genes related to fruit color and flavor through genome-wide association study (GWAS) and transcriptome sequencing. The results indicated that the structural genes of glucose metabolism and phenylpropane pathways were closely related to the contents of aroma substances (such as phenolic acids and flavonoids) (Wang, 2021; Zhang et al., 2024). Weighted gene co-expression network analysis (WGCNA) further screened out some key genes and transcription factors regulating phenylpropane metabolism (such as MYB, bHLH, NAC), whose expression patterns were highly consistent with the accumulation of major aroma components (Figure 1) (Zhang et al., 2024). In addition, the study also speculated that certain β -glucosidase genes are involved in the release of volatile phenolic substances, thereby affecting aroma expression (Zhang et al., 2024). Figure 1 Network analysis dendrogram by WGCNA (Adopted from Zhang et al., 2024) Image caption: (A) Module hierarchical clustering tree diagram. (B) Heat map of key physiological indicators and inter-module correlations. (C) KEGG enrichment map of hub genes in the blue module. (D) Co-expression network of structural genes in phenylpropanoid biosynthesis pathway and transcription factors (Adopted from Zhang et al., 2024) 4.2 Proteomics in aroma biosynthetic enzyme characterization Proteomics provides direct evidence for the study of enzymes related to aroma synthesis. Through the combined analysis of proteomics and metabolomics, the enzymes that catalyze the transformation of key aroma precursors can be located. For example, O-methyltransferase (EjOMT1) is highly expressed in loquat flowers. It can catalyze the methylation of guaiacol-type benzoic acid substances and directly affect the formation of flower fragrance (Koeduka et al., 2016). Proteomics also reveals the changes in the abundance of aroma synthase in different tissues or developmental stages, providing a molecular basis for understanding the dynamic accumulation of aroma substances (Koeduka et al., 2016; Wang, 2021).
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