Analysis on the Effects of Grafting on Tea Plant Metabolites Based on Targeted Metabolomics

In order to explore the difference of metabolites before and after tea tree grafting, tea tree grafting was carried out by cutting and grafting method using "Peach-shaped leaf" as the scion and "Short-grafted pekoe" as the rootstock. Substances in tea plants before and after grafting were detected by using broad-targeted metabolomics technology, and multivariate statistical methods such as principal component analysis (PCA) and orthogonal partial least squares discriminant analysis (OPLS-DA) were used to study the difference of metabolites before and after grafting. The results showed that a total of 804 metabolites were detected in tea samples before and after grafting, of which 105 metabolites were significantly different; Compared with that before grafting, 44 differential metabolites were significantly up-regulated in tea samples after grafting, and 61 differential metabolites were significantly down-regulated, and the number of differential metabolites down-regulated was greater than that up-regulated; In addition, the study on KEGG metabolic pathways revealed that these differential metabolites were mainly distributed in 20 metabolic pathways including purine metabolism, nicotinate and nicotinamide metabolism, glycerol phosphatide metabolism, flavonoid biosynthesis, flavonoid and flavonol biosynthesis, carbon sequestration by photosynthetic organisms, caffeine metabolism, and biosynthesis of secondary metabolites. Among them, there were 24 differential metabolites annotated by KEGG, which were dominated by flavone, nucleotides and their derivatives. In addition, most flavonoids in the pathways were significantly up-regulated, while nucleotides and their derivatives were significantly down-regulated. In conclusion, the content of metabolites of the variety "Peach-shaped leaf" is significantly changed after grafting, which can provide a theoretical reference for the processing and production of grafted tea leaves to a certain extent.