Multiomics analysis reveals that peach gum colouring reflects plant defense responses against pathogenic fungi.

• Peach gum colouring was associated with the total phenolic content that it contained. • Peach gum could be characterized by presence of metabolites and fungal communities. • Gummosis pathogenic fungus had a positive correlation with polyphenols in the gum. • Peach gum colouring may reflect defense response of plant against pathogenic fungi. • Hesperetin, naringenin and eriodictyol constituted the most abundant of flavonoids. In the present study, the differences in the antioxidant capability, metabolite composition and fungal diversity in peach gum with various colours were investigated. Metabolomics revealed that peach gum comprised many small-molecule metabolites (including primary and secondary metabolites), and most polyphenols (such as flavonoids and phenolic acids) showed a significantly positive relationship with the colour deepening, total phenol content and antioxidant capability. Using fungal diversity analysis, the abundance of five fungi at the genus level increased with peach gum colour deepening, and these fungi demonstrated a significantly positive relationship with two defense hormones (salicylic acid and abscisic acid) and most polyphenols (particularly flavonoids). The gummosis pathogenic fungus Botryosphaeria was among the five fungi, suggesting that peach gum colouring may reflect plant defense responses against pathogenic fungi. Additionally, the concentrations of 12 flavonoids in peach gum samples were detected based on LC-QQQ/MS, among which hesperetin, naringenin and eriodictyol were the most abundant. [ABSTRACT FROM AUTHOR]