Aluminum tolerance and secondary metabolites modulation in Ilex paraguariensis: implications for mate composition

Yerba mate (Ilex paraguariensis A. St.-Hil.) is a South American native plant whose leaves are used to produce mate, a traditional hot water infusion. The species is rich in secondary metabolites of economic interest and grows naturally in acidic, low-fertility soils where aluminum (Al) is highly bioavailable. However, the influence of Al on secondary metabolism and infusion composition is poorly understood. We cultivated I. paraguariensis in a hydroponic system with increasing Al concentrations. Plant morphology and photosynthesis parameters were not affected, while reactive oxygen species levels and antioxidant enzymatic activity increased. The concentration of secondary metabolites in the infusion, such as caffeine, chlorogenic acid, and flavonoids, exhibited compound-specific changes. Aluminum was detected in the infusion, but its concentration remained similar across treatments, suggesting that external Al supply does not necessarily transfer to the beverage. These findings indicate that I. paraguariensis is Al tolerant, and that Al modulates yerba mate oxidative metabolism, altering infusion composition without impairing physiological parameters.