Metabolomics reveals antioxidant and antifungal functions of flavonoids in the early stage wounded potato tubers

Wounding could induce the accumulation of flavonoids at wounds in tubers. However, the mechanism by which flavonoids accumulate and their antioxidant and antifungal functions remain unknown. The results demonstrated that wounding increased the expression levels of StCHS1, StCHS2, StCHI1, StCHI2, StF3H1, and StFLS1 at tuber wounds. A total of 114 flavonoids were identified, of which 54 and 64 differential metabolites were found in the unwounded and wounded tubers at 3 and 7 days after wounding, respectively. And 26 differential metabolites were found at 3 and 7 days after wounding. These differential metabolites were mainly enriched in the pathways of flavonoid and flavonol biosynthesis, isoflavone biosynthesis, and anthocyanin biosynthesis. The flavonoids from the tuber wounds showed a greater ability to scavenge DPPH, ABTS+,·OH, and O2·- free radicals and to inhibit the growth and development of Fusarium sulfureum, a dry rot pathogen. Taken together, wounding activates the synthesis of antioxidant and antifungal flavonoids in tuber wounds.