Metabolomics-Based Analysis of Quality Differences in Dendrobium officinale Leaves Under Different Flower Treatments

Abstract

Abstract To elucidate how flower retention regulates leaf quality formation in Dendrobium officinale and to provide a theoretical basis for high-quality leaf cultivation and high-value utilization of byproducts, this study used D. officinale leaves as an experimental material and subjected them to one of two treatments: flower retention (FR) and flower removal (FT). Quality indicators, including the alcohol-soluble extract and the levels of polysaccharides, total flavonoids, total phenols, and free amino acids, were systematically determined, and nontargeted metabolomics was used to analyze metabolic differences between the two groups. The FR group demonstrated a significant change in the levels of polysaccharides, total flavonoids, and total phenols ( P < 0.05) but no significant effect on the alcohol-soluble extract. Compared to the FR group, the FT group demonstrated significantly higher contents of total flavonoids and functional amino acids such as aspartic acid and phenylalanine, whereas the FR group showed a significantly higher accumulation of polysaccharides, total phenols, glutamic acid, and γ-aminobutyric acid. A total of 1999 (39.5%) of the 5062 identified metabolites were expressed significantly differently. The FT group was mainly characterized by upregulated secondary metabolites, including flavonoids and alkaloids, whereas the FR group demonstrated a predominant upregulation of primary metabolites such as lipids and sterols. Kyoto Encyclopedia of Genes and Genomes enrichment analysis indicated that nucleotide metabolism, purine metabolism, aminoacyl-tRNA biosynthesis, and flavonoid biosynthesis as the core differential pathways. Furthermore, the differential metabolites exhibited a metabolic trade-off of “upregulated secondary metabolism and downregulated primary metabolism”. Our findings confirmed that flower removal can significantly increase the active flavonoid components and functional amino acids in D. officinale leaves and optimize the quality of this medicinal leaf by regulating the source–sink relationship, carbon-nitrogen partitioning, and key metabolic pathways.