Ascorbate is the natural substrate for plant peroxidases

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Abstract
Ascorbate‐dependent detoxification of hydrogen peroxide by guaiacol‐type peroxidases is increased considerably in the presence of 3,4‐dihydroxyphenolic compounds, suggesting that ascorbate is the natural substrate for many types of peroxidase in situ and not just the ascorbate‐specific peroxidases. The ascorbate‐dependent destruction of hydrogen peroxide in the more acidic cellular compartments such as the vacuole may be an important function of such non‐specific peroxidases. The stress‐induced production of phenolic compounds would render the guaiacol peroxidases in other less acidic‐cellular sites effective as ascorbate‐dependent H2O2‐detoxifying enzymes.