The Histochemical Localization of Peroxidase in Roots and Its Induction by Indoleacetic Acid

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Abstract
Peroxidase activity was localized and measured in 200 [mu] sections of the primary root of Vicia faba after treatment with indoleacetic acid to elucidate the physiological role of the induced peroxidase in the cell. Only the first 3 mm of the root was used as this area had previously been morphologically analyzed in detail. The cells of the root cap, proepidermis, and vascular tissue including the protophloem and protoxylem show peroxidase activity. However, only the cells of the vascular tissue clearly show the induced formation of peroxidase. The maximum response to indoleacetic acid shifts from the early provascular tissue at 10-8 [image] to the develop-ing protoxylem at 10-7 [image]. The cells that contain peroxidase acitivity are capable of producing a compound when given eugenol and hydrogen peroxide which appears to be an intermediate in lignin biosynthesis. The vascular tissue that has high induced peroxidase is very active in lignin formation.