Immunocytochemical localization and time course of appearance of an anionic peroxidase associated with suberization in wound-healing potato tuber tissue

Abstract

Thin sections of wound-healing potato tuber tissue were stained with rabbit antibody prepared against a suberization-associated anionic peroxidase and then stained with a goat anti-rabbit antibody-fluorescein conjugate. When these sections were examined with an epiilluminating fluorescence microscope, bright green fluorescent linear deposits were observed on the inner side of cell walls in the periderm layer. Initial deposits which were often not contiguous throughout the wall were first observed in some cells after 3 days of wound-healing and subsequently these layers became more pronounced so that all 6 day old periderm cells had green fluorescent layers on their inner walls. This fluorescence was not present in the walls of parenchyma cells or in the walls of periderm cells treated with preimmune serum and anti-rabbit IgG-FITC conjugate. Thin sections of wound-healing potato tissue which were stained with anti-peroxidase antibody and a goat anti-rabbit antibody-rhodamine conjugate exhibited a similar time course of development with a bright reddish-orange fluorescent layer observed on the inside wall of periderm cells. The production of this suberization-associated anionic peroxidase in wound-healing tissue was also demonstrated by an immunobinding dot blot assay which showed that the largest increase in the enzyme level occurred between 4 and 6 days of wound-healing. The present results support the hypothesis that this anionic peroxidase is involved in the deposition of the aromatic polymeric domain of suberin.