Differential Analysis of Metabolites in Different Parts of Rubus chingii Hu Based on Widely Targeted Metabolomics

The differences in metabolite composition among different parts (roots, fruits, leaves and stems) of Rubus chingii Hu (R. chingii) were analyzed using widely targeted metabolomics based on ultra-high performance liquid chromatography-mass spectrometry (UPLC-MS). The results showed that a total of 1726 metabolites were detected, and 610 differential metabolites belonging to 16 classes, such as acids, terpenes, glycosides and flavonoids, were selected between the four parts. Through multivariate statistical analysis and cluster heatmap analysis, it was found that the metabolomes of these four parts were clearly separated from each other, each being clustered into one group. Furthermore, the expression of differential metabolites was generally up-regulated in the leaves compared with the roots, fruits and stems. Flavonoids, the major functional components of R. chingii, were widely distributed in the roots, fruits and leaves. The relative contents of kaempferol-3-O-rutinoside and ellagic acid were the highest in the fruits and roots, respectively. Flavonoid metabolites were abundant in the roots, and the fruits were rich in phenolic acid metabolites. Terpenoids, alkaloids and phenylpropanoids were abundant in the leaves, among which the contents of caffeic acid, chlorogenic acid and salicylic acid were the highest. Gallic acid, catechin, epicatechin and proanthocyanidin derivatives were abundant in the stems. Kyoto Encyclopedia of Genes and Genomes enrichment analysis showed that the differential metabolites were mainly annotated and enriched in flavonoid biosynthesis, steroid hormone biosynthesis, arachidonic acid metabolism, and diterpenoid biosynthesis. The findings provide a theoretical reference for the development and comprehensive utilization of R. chingii, as well as the circular utilization and green development of R. chingii resources.