Implications of stem galls for the structure and phytochemistry of Peumus boldus leaves

Peumus boldus Molina (Monimiaceae) is one of the most widely used medicinal plants in South America. In its stems, the galling insect Dasineura peumi (Diptera; Cecidomyiidae) induces severe anatomical disruption and alters the chemical composition and antioxidant activity of alkaloids and phenolic compounds. However, it remains unknown whether these alterations propagate systemically to the leaves. We hypothesized that this insect also triggers systemic changes in leaves from galled branches, potentially affecting their anatomical structure, biochemical composition, and antioxidant potential. To test this hypothesis, leaves from galled and nongalled branches were analyzed via quantitative assays for phenols, flavonoids, and antioxidant activity, complemented by histochemical staining, anatomical observations, and cytometric comparisons. Our results demonstrated that the structural damage observed in stems does not extend to the leaves, even when they develop above the affected stem region. Nonetheless, both the composition and concentration of polyphenols, including flavonoids, were significantly altered but in contrasting patterns: the total polyphenol content increased in leaves from galled branches, whereas the flavonoid content decreased. Furthermore, stem gall induction modified the profile of the polyphenol subclasses and individual compounds in the leaves. Despite these biochemical shifts, the antioxidant capacity of the leaves remained stable, suggesting a compensatory balance in the antioxidant system of P. boldus . These findings highlight the ecological role of secondary metabolites in mediating plant–insect interactions, providing novel evidence that insect-induced galls on P. boldus stems trigger systemic alterations in the phytochemical profile of the host plant. • Dasineura peumi galls modify phenolic profiles in Peumus boldus leaves. • Polyphenols increase but flavonoids decrease in the leaves of galled branches. • Stem gall induction altered the polyphenol profile in leaves. • The antioxidant capacity of leaves remains unaffected by galls. • The structural damage observed in stems does not extend to the leaves.