Abstract: 【Objective】The objective of this study is to reveal the underlying biochemical mechanisms related to the resistance and susceptibility of peach towards herbivory by Myzus persicae, and to identify the key secondary metabolites of peach responding to the M. persicae infection.【Method】Young leaves of resistant and susceptible peach trees were inoculated with M. persicae for 3 days and used for secondary metabolite extraction and UPLC-MS/MS analysis. Differentially altered metabolites (DAMs) were screened with |log₂ fold change|≥1, q-value≤0.01 as threshold. The VIP value of the OPLS-DA model was used to perform differences between resistant and susceptible peach. By comparing the concentration difference between the resistant and susceptible varieties of peach after M. persicae feeding, the role of DAMs was explored.【Result】To illustrate the biochemical mechanisms of M. persicae resistance in peach, aphid-resistant/aphid-susceptible peach varieties infested with GPAs for 3 days. Widely targeted metabolomics analysis of the infested tissues identified 528 metabolites. Using principal component analysis (PCA), hierarchical cluster analysis (HCA) and venn diagram analysis, it was found that 7 differentially altered metabolites (DAMs) were identified from the susceptible varieties Zhong You 13 (CN13), and 2 of them were significantly decreased, 5 of them were significantly decreased. 7 DAMs were identified from the susceptible varieties Zhong Nong Jin Hui (ZNJH), and 3 of them were significantly decreased, 4 of them were significantly decreased. 33 DAMs were identified from the resistant varieties‘96-5-1’ (9651), and one of them was significantly decreased, 32 of them were significantly decreased. 55 DAMs were identified from the resistant varieties ZaoYouTao (ZYT), and 12 of them were significantly decreased, 43 of them were significantly decreased. The majority of the DAMs were identified from the two resistant varieties, and the overall magnitude of change was greater in the resistant varieties than in the susceptible varieties. Finally, 15 secondary metabolites (6 amino acid and derivatives, 5 phenolic acids, 3 nucleotides and derivatives, and 1 organic acid) were considered to be involved in M. persicae resistance of ‘Shou xing tao’.【Conclusion】The significantly up-regulated secondary metabolites obtained in M. persicae-resistant peach varieties were mainly involved in the response M. persicae feeding. The regulation of these secondary metabolites (amino acids and their derivatives, phenolic acids, nucleotides and their derivatives) is the important mechanism of defense reaction to M. persicae.

Key words: peach, green peach aphid (Myzus persicae), resistance, metabolomics, secondary metabolite, UPLC-MS/MS